Deformation of polyiodides in Cs₂I₈ crystals at high pressure

Dicaesium octaiodide is composed of layers of zigzag polyiodide units (I₈²⁻) intercalated with caesium cations. Each I₈²⁻ unit is built of two triiodides bridged with one diiodine molecules. This system was subjected to compression up to 5.9 GPa under hydro­static conditions. Pressure alters the supramolecular architecture around I₈²⁻, leading to bending of the triiodide units away from their energetically preferred geometry (D_∞h). Short I₂...I₃⁻ contacts compress significantly, reaching lengths typical for the covalently bonded polyiodides. Unlike in reported structures at ambient conditions, pressure-induced catenation proceeds without symmetrization of the polyiodides, pointing to a different electron-transfer mechanism. The structure is shown to be half as compressible [B₀ = 12.9 (4) GPa] than the similar CsI₃ structure. The high bulk modulus is associated with higher I—I connectivity and a more compact cationic net, than in CsI₃. The small discontinuity in the compressibility trend around 3 GPa suggests formation of more covalent I—I bonds. The potential sources of this discontinuity and its implication on the electronic properties of Cs₂I₈ are discussed.

Computing details

Data collection: CrysAlis PRO 1.171.41.110a (Rigaku OD, 2021) for CsI4_0p0001GPa; CrysAlis PRO 1.171.40.67a (Rigaku OD, 2019) for CsI4_0p43GPa, CsI4_0p91GPa, CsI4_1p15GPa, CsI4_1p65GPa; CrysAlis PRO 1.171.41.93a (Rigaku OD, 2020) for CsI4_1p97GPa, CsI4_2p32GPa, CsI4_2p74GPa, CsI4_3p05GPa, CsI4_4p19GPa, CsI4_4p71GPa, CsI4_5p42GPa, CsI4_5p91GPa; CrysAlis PRO 1.171.40.84a (Rigaku OD, 2020) for CsI4_3p33GPa. Cell refinement: CrysAlis PRO 1.171.41.110a (Rigaku OD, 2021) for CsI4_0p0001GPa; CrysAlis PRO 1.171.40.67a (Rigaku OD, 2019) for CsI4_0p43GPa, CsI4_0p91GPa, CsI4_1p15GPa, CsI4_1p65GPa; CrysAlis PRO 1.171.41.93a (Rigaku OD, 2020) for CsI4_1p97GPa, CsI4_2p32GPa, CsI4_2p74GPa, CsI4_3p05GPa, CsI4_4p19GPa, CsI4_4p71GPa, CsI4_5p42GPa, CsI4_5p91GPa; CrysAlis PRO 1.171.40.84a (Rigaku OD, 2020) for CsI4_3p33GPa. Data reduction: CrysAlis PRO 1.171.41.110a (Rigaku OD, 2021) for CsI4_0p0001GPa; CrysAlis PRO 1.171.40.67a (Rigaku OD, 2019) for CsI4_0p43GPa, CsI4_0p91GPa, CsI4_1p15GPa, CsI4_1p65GPa; CrysAlis PRO 1.171.41.93a (Rigaku OD, 2020) for CsI4_1p97GPa, CsI4_2p32GPa, CsI4_2p74GPa, CsI4_3p05GPa, CsI4_4p19GPa, CsI4_4p71GPa, CsI4_5p42GPa, CsI4_5p91GPa; CrysAlis PRO 1.171.40.84a (Rigaku OD, 2020) for CsI4_3p33GPa. Program(s) used to solve structure: SHELXT 2018/2 (Sheldrick, 2018) for CsI4_0p0001GPa, CsI4_3p33GPa; SHELXT (Sheldrick, 2015) for CsI4_0p43GPa; SHELXT 2014/5 (Sheldrick, 2014) for CsI4_2p32GPa, CsI4_2p74GPa, CsI4_3p05GPa, CsI4_4p71GPa, CsI4_5p42GPa, CsI4_5p91GPa; olex2.solve 1.3 (Bourhis et al., 2015) for CsI4_4p19GPa. Program(s) used to refine structure: SHELXL 2018/3 (Sheldrick, 2015) for CsI4_0p0001GPa, CsI4_0p43GPa, CsI4_0p91GPa, CsI4_1p15GPa, CsI4_1p65GPa, CsI4_1p97GPa, CsI4_2p32GPa, CsI4_2p74GPa, CsI4_3p05GPa, CsI4_3p33GPa, CsI4_4p71GPa, CsI4_5p42GPa, CsI4_5p91GPa; olex2.refine 1.3 (Bourhis et al., 2015) for CsI4_4p19GPa. For all structures, molecular graphics: Olex2 1.3 (Dolomanov et al., 2009); software used to prepare material for publication: Olex2 1.3 (Dolomanov et al., 2009).

dicesium octaiodide (CsI4_0p0001GPa)

Crystal data

CsI4	F(000) = 1068
Mr = 640.51	Dx = 4.519 Mg m^−3
Monoclinic, P21/c	Synchrotron radiation, λ = 0.41077 Å
a = 10.2847 (9) Å	Cell parameters from 1143 reflections
b = 8.9809 (1) Å	θ = 1.8–19.9°
c = 11.2100 (4) Å	µ = 3.84 mm^−1
β = 114.598 (7)°	T = 296 K
V = 941.46 (10) Å^3	Plate, dark red
Z = 4	0.04 × 0.02 × 0.01 mm

Data collection

Esperanto-CrysAlisPro-abstract goniometer imported esperanto images diffractometer	1881 independent reflections
Radiation source: undulator, ID15B, ESRF	1474 reflections with I > 2σ(I)
Synchrotron monochromator	Rint = 0.019
Detector resolution: 13.3333 pixels mm^-1	θmax = 21.2°, θmin = 1.8°
phi scan	h = −8→8
Absorption correction: multi-scan CrysAlisPro 1.171.41.110a (Rigaku Oxford Diffraction, 2021) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −15→15
Tmin = 0.406, Tmax = 1.000	l = −19→18
3490 measured reflections

Refinement

Refinement on F^2	46 parameters
Least-squares matrix: full	0 restraints
R[F^2 > 2σ(F^2)] = 0.032	w = 1/[σ^2(Fo^2) + (0.0461P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.090	(Δ/σ)max = 0.001
S = 0.99	Δρmax = 0.66 e Å^−3
1881 reflections	Δρmin = −0.82 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
I2	0.37997 (8)	0.70803 (4)	0.39214 (4)	0.0498 (3)
Cs1	0.77568 (10)	0.87459 (5)	0.69681 (4)	0.0607 (3)
I1	0.55970 (10)	0.89915 (5)	0.32404 (5)	0.0590 (3)
I3	0.17152 (10)	0.51486 (4)	0.44968 (5)	0.0579 (3)
I4	0.04999 (10)	0.85835 (5)	0.49453 (4)	0.0568 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I2	0.0560 (9)	0.04619 (19)	0.04879 (19)	0.00599 (19)	0.0235 (3)	−0.00228 (12)
Cs1	0.0643 (10)	0.0608 (2)	0.0569 (2)	0.0087 (2)	0.0252 (4)	0.00739 (14)
I1	0.0565 (11)	0.0629 (3)	0.0634 (3)	−0.0026 (3)	0.0307 (4)	0.00422 (17)
I3	0.0599 (9)	0.0471 (2)	0.0729 (3)	−0.0017 (2)	0.0336 (4)	0.00536 (15)
I4	0.0536 (10)	0.0545 (2)	0.0601 (2)	−0.0100 (2)	0.0216 (4)	−0.00195 (15)

Geometric parameters (Å, º)

I2—Cs1^i	4.0347 (6)	Cs1—I3^iii	3.9743 (6)
I2—Cs1	4.3467 (11)	Cs1—I3^iv	3.9959 (6)
I2—I1	2.8497 (10)	Cs1—I3^v	3.9985 (12)
I2—I3	3.0287 (10)	Cs1—I4^v	3.9542 (8)
Cs1—I1^i	3.9255 (12)	Cs1—I4^vi	4.2951 (12)
Cs1—I1	3.8364 (7)	Cs1—I4^i	4.0950 (9)
Cs1—I1^ii	3.9560 (10)	I4—I4^vii	2.7659 (11)
Cs1^i—I2—Cs1	91.137 (16)	I3^v—Cs1—I2^i	97.277 (17)
I1—I2—Cs1	60.240 (19)	I3^iii—Cs1—I3^iv	134.562 (15)
I1—I2—Cs1^i	66.99 (2)	I3^iv—Cs1—I3^v	103.66 (2)
I1—I2—I3	176.08 (3)	I3^iii—Cs1—I3^v	62.50 (2)
I3—I2—Cs1	122.957 (17)	I3^v—Cs1—I4^i	71.778 (19)
I3—I2—Cs1^i	109.97 (3)	I3^v—Cs1—I4^vi	71.58 (2)
I2^i—Cs1—I2	88.863 (16)	I3^iv—Cs1—I4^vi	61.435 (15)
I2^i—Cs1—I4^vi	100.444 (15)	I3^iv—Cs1—I4^i	97.664 (18)
I2^i—Cs1—I4^i	62.716 (16)	I3^iii—Cs1—I4^i	115.389 (17)
I1^ii—Cs1—I2^i	116.23 (2)	I3^iii—Cs1—I4^vi	133.63 (3)
I1^ii—Cs1—I2	65.595 (17)	I4^v—Cs1—I2^i	140.392 (15)
I1—Cs1—I2	40.154 (15)	I4^vi—Cs1—I2	100.335 (15)
I1—Cs1—I2^i	71.767 (12)	I4^v—Cs1—I2	125.931 (17)
I1^i—Cs1—I2^i	41.926 (14)	I4^i—Cs1—I2	105.123 (14)
I1^i—Cs1—I2	67.621 (19)	I4^v—Cs1—I1^ii	71.175 (19)
I1—Cs1—I1^ii	105.72 (3)	I4^v—Cs1—I3^v	51.306 (16)
I1^i—Cs1—I1^ii	74.445 (17)	I4^v—Cs1—I3^iv	73.291 (14)
I1—Cs1—I1^i	79.01 (2)	I4^v—Cs1—I3^iii	64.707 (14)
I1^ii—Cs1—I3^iii	72.642 (15)	I4^v—Cs1—I4^vi	91.89 (3)
I1—Cs1—I3^iv	73.668 (14)	I4^i—Cs1—I4^vi	38.402 (15)
I1^ii—Cs1—I3^iv	78.284 (15)	I4^v—Cs1—I4^i	115.97 (2)
I1^ii—Cs1—I3^v	117.228 (16)	I2—I1—Cs1^viii	104.267 (18)
I1—Cs1—I3^iii	147.65 (3)	I2—I1—Cs1	79.607 (18)
I1^i—Cs1—I3^iii	69.345 (18)	I2—I1—Cs1^i	71.09 (3)
I1—Cs1—I3^v	135.64 (2)	Cs1—I1—Cs1^viii	101.51 (2)
I1^i—Cs1—I3^v	121.587 (16)	Cs1—I1—Cs1^i	100.99 (2)
I1^i—Cs1—I3^iv	134.02 (3)	Cs1^i—I1—Cs1^viii	155.720 (19)
I1^ii—Cs1—I4^i	170.68 (2)	I2—I3—Cs1^ix	125.37 (3)
I1^ii—Cs1—I4^vi	139.466 (15)	I2—I3—Cs1^x	107.990 (19)
I1—Cs1—I4^i	64.978 (17)	I2—I3—Cs1^iv	100.63 (2)
I1—Cs1—I4^v	146.716 (18)	Cs1^ix—I3—Cs1^x	117.50 (2)
I1^i—Cs1—I4^i	103.362 (17)	Cs1^ix—I3—Cs1^iv	98.442 (10)
I1—Cs1—I4^vi	68.692 (19)	Cs1^iv—I3—Cs1^x	101.445 (19)
I1^i—Cs1—I4^vi	137.740 (14)	Cs1^i—I4—Cs1^xi	141.597 (15)
I1^i—Cs1—I4^v	128.656 (19)	Cs1^x—I4—Cs1^xi	93.95 (3)
I3^v—Cs1—I2	170.57 (2)	Cs1^x—I4—Cs1^i	100.481 (15)
I3^iv—Cs1—I2	67.593 (17)	I4^vii—I4—Cs1^xi	66.88 (3)
I3^iv—Cs1—I2^i	145.029 (14)	I4^vii—I4—Cs1^x	112.11 (4)
I3^iii—Cs1—I2	125.96 (3)	I4^vii—I4—Cs1^i	74.72 (2)
I3^iii—Cs1—I2^i	80.063 (12)

Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, −y+3/2, z+1/2; (iii) −x+1, y+1/2, −z+3/2; (iv) −x+1, −y+1, −z+1; (v) x+1, −y+3/2, z+1/2; (vi) x+1, y, z; (vii) −x, −y+2, −z+1; (viii) x, −y+3/2, z−1/2; (ix) −x+1, y−1/2, −z+3/2; (x) x−1, −y+3/2, z−1/2; (xi) x−1, y, z.

dicesium octaiodide (CsI4_0p43GPa)

Crystal data

CsI4	F(000) = 1068
Mr = 640.51	Dx = 4.717 Mg m^−3
Monoclinic, P21/c	Synchrotron radiation, λ = 0.41077 Å
a = 10.1323 (13) Å	Cell parameters from 1544 reflections
b = 8.88899 (15) Å	θ = 2.2–20.8°
c = 11.0453 (4) Å	µ = 4.04 mm^−1
β = 114.957 (9)°	T = 296 K
V = 901.92 (14) Å^3	Plate, dark red
Z = 4	0.04 × 0.02 × 0.01 mm

Data collection

Esperanto-CrysAlisPro-abstract goniometer imported esperanto images diffractometer	1137 independent reflections
Radiation source: undulator, ID15B, ESRF	1016 reflections with I > 2σ(I)
Synchrotron monochromator	Rint = 0.019
Detector resolution: 13.3333 pixels mm^-1	θmax = 20.0°, θmin = 2.2°
phi scan	h = −6→7
Absorption correction: multi-scan CrysAlisPro 1.171.40.67a (Rigaku Oxford Diffraction, 2019) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −12→12
Tmin = 0.362, Tmax = 1.000	l = −16→16
2140 measured reflections

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Primary atom site location: dual
R[F^2 > 2σ(F^2)] = 0.033	w = 1/[σ^2(Fo^2) + (0.0702P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.100	(Δ/σ)max = 0.001
S = 1.04	Δρmax = 0.99 e Å^−3
1137 reflections	Δρmin = −0.77 e Å^−3
46 parameters

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
I2	0.38162 (11)	0.70932 (5)	0.39270 (4)	0.0449 (5)
Cs1	0.77696 (13)	0.87545 (5)	0.69514 (4)	0.0533 (6)
I1	0.56057 (15)	0.90216 (6)	0.32020 (5)	0.0519 (6)
I3	0.17247 (13)	0.51192 (5)	0.45101 (5)	0.0521 (5)
I4	0.05067 (13)	0.85662 (6)	0.49563 (5)	0.0515 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I2	0.0580 (14)	0.0376 (3)	0.0407 (2)	0.0044 (3)	0.0224 (4)	−0.00185 (12)
Cs1	0.0655 (17)	0.0487 (3)	0.0459 (3)	0.0066 (3)	0.0236 (5)	0.00552 (13)
I1	0.0584 (18)	0.0514 (3)	0.0510 (3)	−0.0015 (4)	0.0280 (5)	0.00371 (16)
I3	0.0636 (15)	0.0374 (3)	0.0594 (3)	−0.0014 (3)	0.0299 (5)	0.00439 (15)
I4	0.0594 (17)	0.0431 (3)	0.0502 (3)	−0.0086 (3)	0.0215 (5)	−0.00236 (14)

Geometric parameters (Å, º)

I2—Cs1^i	3.9787 (8)	Cs1—I3^iii	3.9272 (8)
I2—Cs1	4.2537 (14)	Cs1—I3^iv	3.9359 (16)
I2—I1	2.8447 (13)	Cs1—I3^v	3.9140 (7)
I2—I3	3.0227 (12)	Cs1—I4^iv	3.8981 (10)
Cs1—I1^i	3.8914 (17)	Cs1—I4^vi	4.2110 (14)
Cs1—I1	3.7884 (9)	Cs1—I4^i	4.0334 (11)
Cs1—I1^ii	3.9192 (13)	I4—I4^vii	2.7648 (14)
Cs1^i—I2—Cs1	91.09 (2)	I3^v—Cs1—I1^ii	72.555 (19)
I1—I2—Cs1	60.73 (2)	I3^iii—Cs1—I3^iv	104.37 (3)
I1—I2—Cs1^i	67.18 (3)	I3^v—Cs1—I3^iii	134.217 (16)
I1—I2—I3	175.73 (4)	I3^v—Cs1—I3^iv	62.58 (3)
I3—I2—Cs1	123.146 (19)	I3^iii—Cs1—I4^i	98.20 (2)
I3—I2—Cs1^i	110.07 (3)	I3^v—Cs1—I4^i	115.82 (2)
I2^i—Cs1—I2	88.91 (2)	I3^iii—Cs1—I4^vi	61.38 (2)
I2^i—Cs1—I4^vi	101.340 (19)	I3^iv—Cs1—I4^i	71.99 (2)
I2^i—Cs1—I4^i	62.88 (2)	I3^v—Cs1—I4^vi	134.20 (4)
I1^ii—Cs1—I2^i	116.21 (3)	I3^iv—Cs1—I4^vi	71.94 (3)
I1^i—Cs1—I2^i	42.360 (18)	I4^iv—Cs1—I2	125.51 (2)
I1—Cs1—I2	40.92 (2)	I4^vi—Cs1—I2	100.668 (19)
I1^i—Cs1—I2	67.86 (3)	I4^i—Cs1—I2	105.461 (17)
I1^ii—Cs1—I2	64.96 (2)	I4^iv—Cs1—I2^i	140.137 (18)
I1—Cs1—I2^i	71.784 (16)	I4^iv—Cs1—I1^ii	70.70 (3)
I1—Cs1—I1^i	80.09 (3)	I4^iv—Cs1—I3^v	64.369 (18)
I1^i—Cs1—I1^ii	73.93 (2)	I4^iv—Cs1—I3^iii	73.539 (18)
I1—Cs1—I1^ii	105.84 (4)	I4^iv—Cs1—I3^iv	51.70 (2)
I1^ii—Cs1—I3^iv	117.30 (2)	I4^iv—Cs1—I4^i	116.61 (3)
I1^ii—Cs1—I3^iii	77.42 (2)	I4^i—Cs1—I4^vi	39.11 (2)
I1^i—Cs1—I3^iii	133.80 (4)	I4^iv—Cs1—I4^vi	92.03 (3)
I1—Cs1—I3^iv	135.50 (3)	I2—I1—Cs1	78.36 (2)
I1—Cs1—I3^v	147.53 (4)	I2—I1—Cs1^i	70.46 (4)
I1^i—Cs1—I3^iv	120.79 (2)	I2—I1—Cs1^viii	103.75 (2)
I1—Cs1—I3^iii	73.818 (17)	Cs1—I1—Cs1^viii	101.19 (3)
I1^i—Cs1—I3^v	68.19 (2)	Cs1—I1—Cs1^i	99.91 (3)
I1^i—Cs1—I4^iv	127.04 (2)	Cs1^i—I1—Cs1^viii	156.43 (3)
I1—Cs1—I4^i	64.56 (2)	I2—I3—Cs1^ix	107.00 (2)
I1^ii—Cs1—I4^i	170.35 (3)	I2—I3—Cs1^x	125.77 (3)
I1^i—Cs1—I4^vi	139.300 (16)	I2—I3—Cs1^iii	101.34 (3)
I1^ii—Cs1—I4^vi	138.530 (18)	Cs1^x—I3—Cs1^ix	117.42 (3)
I1—Cs1—I4^iv	147.10 (2)	Cs1^iii—I3—Cs1^ix	101.41 (3)
I1^i—Cs1—I4^i	104.10 (2)	Cs1^x—I3—Cs1^iii	98.852 (12)
I1—Cs1—I4^vi	68.63 (3)	Cs1^ix—I4—Cs1^xi	94.45 (4)
I3^v—Cs1—I2^i	79.936 (16)	Cs1^i—I4—Cs1^xi	140.89 (2)
I3^iv—Cs1—I2	171.24 (3)	Cs1^ix—I4—Cs1^i	100.194 (19)
I3^iv—Cs1—I2^i	97.08 (2)	I4^vii—I4—Cs1^xi	66.97 (4)
I3^v—Cs1—I2	125.10 (4)	I4^vii—I4—Cs1^ix	112.11 (5)
I3^iii—Cs1—I2^i	145.329 (16)	I4^vii—I4—Cs1^i	73.91 (3)
I3^iii—Cs1—I2	67.40 (2)

Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, −y+3/2, z+1/2; (iii) −x+1, −y+1, −z+1; (iv) x+1, −y+3/2, z+1/2; (v) −x+1, y+1/2, −z+3/2; (vi) x+1, y, z; (vii) −x, −y+2, −z+1; (viii) x, −y+3/2, z−1/2; (ix) x−1, −y+3/2, z−1/2; (x) −x+1, y−1/2, −z+3/2; (xi) x−1, y, z.

dicesium octaiodide (CsI4_0p91GPa)

Crystal data

CsI4	F(000) = 1068
Mr = 640.51	Dx = 4.905 Mg m^−3
Monoclinic, P21/c	Synchrotron radiation, λ = 0.41077 Å
a = 9.997 (3) Å	Cell parameters from 1172 reflections
b = 8.8025 (3) Å	θ = 2.2–20.8°
c = 10.9003 (8) Å	µ = 4.20 mm^−1
β = 115.28 (2)°	T = 296 K
V = 867.3 (3) Å^3	Plate, dark red
Z = 4

Data collection

Esperanto-CrysAlisPro-abstract goniometer imported esperanto images diffractometer	1090 independent reflections
Radiation source: undulator, ID15B, ESRF	975 reflections with I > 2σ(I)
Synchrotron monochromator	Rint = 0.015
Detector resolution: 13.3333 pixels mm^-1	θmax = 20.0°, θmin = 2.2°
phi scan	h = −7→6
Absorption correction: multi-scan CrysAlisPro 1.171.40.67a (Rigaku Oxford Diffraction, 2019) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −12→12
Tmin = 0.617, Tmax = 1.000	l = −16→16
2040 measured reflections

Refinement

Refinement on F^2	46 parameters
Least-squares matrix: full	0 restraints
R[F^2 > 2σ(F^2)] = 0.036	w = 1/[σ^2(Fo^2) + (0.0712P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.107	(Δ/σ)max < 0.001
S = 1.11	Δρmax = 0.92 e Å^−3
1090 reflections	Δρmin = −0.56 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
I2	0.38329 (14)	0.71059 (6)	0.39350 (5)	0.0404 (6)
Cs1	0.77791 (16)	0.87646 (6)	0.69386 (5)	0.0475 (6)
I1	0.56108 (18)	0.90461 (7)	0.31697 (6)	0.0470 (6)
I3	0.17332 (16)	0.50911 (7)	0.45182 (6)	0.0451 (6)
I4	0.05123 (16)	0.85512 (7)	0.49652 (6)	0.0446 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I2	0.0438 (17)	0.0423 (3)	0.0379 (3)	0.0042 (3)	0.0202 (5)	−0.00180 (14)
Cs1	0.0511 (19)	0.0510 (3)	0.0406 (3)	0.0055 (3)	0.0196 (5)	0.00409 (15)
I1	0.047 (2)	0.0542 (4)	0.0450 (3)	−0.0015 (4)	0.0244 (6)	0.00334 (18)
I3	0.0450 (18)	0.0422 (3)	0.0527 (3)	−0.0005 (4)	0.0252 (6)	0.00424 (17)
I4	0.0412 (19)	0.0461 (3)	0.0461 (3)	−0.0072 (3)	0.0183 (6)	−0.00251 (16)

Geometric parameters (Å, º)

I2—Cs1^i	3.9251 (9)	Cs1—I3^iii	3.8652 (9)
I2—Cs1	4.1692 (19)	Cs1—I3^iv	3.880 (2)
I2—I1	2.8351 (16)	Cs1—I3^v	3.8613 (8)
I2—I3	3.0158 (14)	Cs1—I4^vi	4.1409 (18)
Cs1—Cs1^i	5.780 (3)	Cs1—I4^iv	3.8479 (14)
Cs1—I1^i	3.856 (2)	Cs1—I4^i	3.9793 (13)
Cs1—I1	3.7459 (12)	I4—I4^vii	2.7617 (16)
Cs1—I1^ii	3.8864 (15)
Cs1^i—I2—Cs1	91.09 (3)	I3^iii—Cs1—I1^ii	76.68 (2)
I1—I2—Cs1	61.20 (3)	I3^v—Cs1—I1^ii	72.42 (2)
I1—I2—Cs1^i	67.34 (4)	I3^iv—Cs1—I1^ii	117.44 (3)
I1—I2—I3	175.20 (4)	I3^iii—Cs1—I3^iv	104.92 (3)
I3—I2—Cs1	123.42 (2)	I3^v—Cs1—I3^iv	62.75 (4)
I3—I2—Cs1^i	110.19 (4)	I3^v—Cs1—I3^iii	133.811 (19)
I2^i—Cs1—I2	88.91 (3)	I3^iv—Cs1—I4^vi	72.19 (3)
I2—Cs1—Cs1^i	42.76 (2)	I3^iv—Cs1—I4^i	72.09 (3)
I2^i—Cs1—Cs1^i	46.151 (18)	I3^iii—Cs1—I4^i	98.60 (3)
I2^i—Cs1—I4^i	63.05 (3)	I3^iii—Cs1—I4^vi	61.30 (2)
I2^i—Cs1—I4^vi	102.10 (2)	I3^v—Cs1—I4^i	116.30 (3)
I1^ii—Cs1—I2^i	116.20 (4)	I3^v—Cs1—I4^vi	134.73 (5)
I1^ii—Cs1—I2	64.41 (3)	I4^iv—Cs1—I2	125.11 (3)
I1—Cs1—I2^i	71.779 (19)	I4^i—Cs1—I2	105.74 (2)
I1^i—Cs1—I2	68.07 (3)	I4^iv—Cs1—I2^i	140.02 (2)
I1^i—Cs1—I2^i	42.72 (2)	I4^vi—Cs1—I2	100.90 (3)
I1—Cs1—I2	41.55 (3)	I4^iv—Cs1—Cs1^i	159.26 (4)
I1—Cs1—Cs1^i	41.22 (3)	I4^vi—Cs1—Cs1^i	106.19 (2)
I1^ii—Cs1—Cs1^i	89.33 (4)	I4^i—Cs1—Cs1^i	83.57 (3)
I1^i—Cs1—Cs1^i	39.80 (2)	I4^iv—Cs1—I1^i	125.73 (3)
I1—Cs1—I1^i	81.02 (3)	I4^iv—Cs1—I1^ii	70.32 (3)
I1^i—Cs1—I1^ii	73.52 (3)	I4^iv—Cs1—I3^v	64.05 (2)
I1—Cs1—I1^ii	105.90 (4)	I4^iv—Cs1—I3^iii	73.69 (2)
I1^i—Cs1—I3^v	67.26 (3)	I4^iv—Cs1—I3^iv	52.08 (3)
I1^i—Cs1—I3^iv	120.16 (3)	I4^i—Cs1—I4^vi	39.70 (2)
I1—Cs1—I3^iv	135.31 (4)	I4^iv—Cs1—I4^i	117.12 (4)
I1—Cs1—I3^v	147.54 (4)	I4^iv—Cs1—I4^vi	92.11 (4)
I1^i—Cs1—I3^iii	133.60 (4)	I2—I1—Cs1^i	69.94 (4)
I1—Cs1—I3^iii	73.916 (19)	I2—I1—Cs1^viii	103.31 (3)
I1^i—Cs1—I4^i	104.75 (3)	I2—I1—Cs1	77.25 (3)
I1—Cs1—I4^vi	68.56 (3)	Cs1—I1—Cs1^viii	100.94 (4)
I1^i—Cs1—I4^vi	140.62 (2)	Cs1—I1—Cs1^i	98.98 (3)
I1—Cs1—I4^i	64.21 (3)	Cs1^i—I1—Cs1^viii	156.92 (3)
I1^ii—Cs1—I4^i	170.05 (3)	I2—I3—Cs1^ix	125.92 (4)
I1—Cs1—I4^iv	147.33 (3)	I2—I3—Cs1^x	106.26 (3)
I1^ii—Cs1—I4^vi	137.69 (2)	I2—I3—Cs1^iii	102.04 (4)
I3^iii—Cs1—I2^i	145.51 (2)	Cs1^ix—I3—Cs1^x	117.25 (4)
I3^v—Cs1—I2^i	79.98 (2)	Cs1^ix—I3—Cs1^iii	99.275 (15)
I3^iv—Cs1—I2	171.71 (3)	Cs1^iii—I3—Cs1^x	101.45 (3)
I3^v—Cs1—I2	124.36 (5)	Cs1^i—I4—Cs1^xi	140.30 (2)
I3^iv—Cs1—I2^i	96.95 (3)	Cs1^x—I4—Cs1^xi	94.87 (4)
I3^iii—Cs1—I2	67.23 (3)	Cs1^x—I4—Cs1^i	99.97 (2)
I3^iii—Cs1—Cs1^i	106.29 (3)	I4^vii—I4—Cs1^xi	66.99 (4)
I3^iv—Cs1—Cs1^i	142.75 (2)	I4^vii—I4—Cs1^x	112.14 (6)
I3^v—Cs1—Cs1^i	106.79 (4)	I4^vii—I4—Cs1^i	73.30 (4)

Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, −y+3/2, z+1/2; (iii) −x+1, −y+1, −z+1; (iv) x+1, −y+3/2, z+1/2; (v) −x+1, y+1/2, −z+3/2; (vi) x+1, y, z; (vii) −x, −y+2, −z+1; (viii) x, −y+3/2, z−1/2; (ix) −x+1, y−1/2, −z+3/2; (x) x−1, −y+3/2, z−1/2; (xi) x−1, y, z.

dicesium octaiodide (CsI4_1p15GPa)

Crystal data

CsI4	F(000) = 1068
Mr = 640.51	Dx = 5.004 Mg m^−3
Monoclinic, P21/c	Synchrotron radiation, λ = 0.41077 Å
a = 9.934 (2) Å	Cell parameters from 1195 reflections
b = 8.7538 (2) Å	θ = 2.8–21.0°
c = 10.8339 (6) Å	µ = 4.28 mm^−1
β = 115.517 (14)°	T = 296 K
V = 850.2 (2) Å^3	Plate, dark red
Z = 4	0.04 × 0.02 × 0.01 mm

Data collection

Esperanto-CrysAlisPro-abstract goniometer imported esperanto images diffractometer	1069 independent reflections
Radiation source: undulator, ID15B, ESRF	966 reflections with I > 2σ(I)
Synchrotron monochromator	Rint = 0.020
Detector resolution: 13.3333 pixels mm^-1	θmax = 20.0°, θmin = 2.2°
phi scan	h = −6→7
Absorption correction: multi-scan CrysAlisPro 1.171.40.67a (Rigaku Oxford Diffraction, 2019) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −12→11
Tmin = 0.499, Tmax = 1.000	l = −16→16
1961 measured reflections

Refinement

Refinement on F^2	46 parameters
Least-squares matrix: full	0 restraints
R[F^2 > 2σ(F^2)] = 0.031	w = 1/[σ^2(Fo^2) + (0.0634P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.087	(Δ/σ)max = 0.001
S = 1.01	Δρmax = 0.63 e Å^−3
1069 reflections	Δρmin = −0.60 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
I2	0.38421 (11)	0.71097 (4)	0.39399 (4)	0.0475 (5)
Cs1	0.77817 (12)	0.87731 (5)	0.69329 (4)	0.0533 (5)
I1	0.56125 (14)	0.90554 (5)	0.31547 (5)	0.0526 (5)
I3	0.17355 (13)	0.50757 (5)	0.45210 (5)	0.0519 (5)
I4	0.05150 (12)	0.85435 (5)	0.49702 (4)	0.0515 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I2	0.0596 (14)	0.0471 (2)	0.0366 (2)	0.0034 (3)	0.0213 (4)	−0.00183 (11)
Cs1	0.0647 (15)	0.0547 (3)	0.0390 (2)	0.0051 (2)	0.0210 (4)	0.00359 (11)
I1	0.0593 (15)	0.0586 (3)	0.0420 (2)	−0.0019 (3)	0.0240 (5)	0.00306 (14)
I3	0.0611 (14)	0.0464 (3)	0.0501 (3)	−0.0004 (3)	0.0257 (4)	0.00352 (12)
I4	0.0578 (15)	0.0499 (3)	0.0443 (2)	−0.0065 (3)	0.0197 (4)	−0.00214 (12)

Geometric parameters (Å, º)

I2—Cs1^i	3.8950 (7)	Cs1—I3^iii	3.8493 (16)
I2—Cs1	4.1253 (15)	Cs1—I3^iv	3.8343 (6)
I2—I1	2.8297 (12)	Cs1—I3^v	3.8358 (7)
I2—I3	3.0135 (12)	Cs1—I4^vi	4.1121 (15)
Cs1—Cs1^i	5.723 (2)	Cs1—I4^iii	3.8230 (11)
Cs1—I1^i	3.8362 (17)	Cs1—I4^i	3.9545 (10)
Cs1—I1	3.7229 (9)	I4—I4^vii	2.7587 (13)
Cs1—I1^ii	3.8709 (12)
Cs1^i—I2—Cs1	91.01 (2)	I3^v—Cs1—I1^ii	76.412 (18)
I1—I2—Cs1^i	67.43 (3)	I3^v—Cs1—I1^i	133.56 (3)
I1—I2—Cs1	61.43 (3)	I3^iv—Cs1—I1^i	66.84 (3)
I1—I2—I3	174.84 (3)	I3^iv—Cs1—I3^v	133.539 (15)
I3—I2—Cs1	123.601 (19)	I3^iv—Cs1—I3^iii	62.89 (3)
I3—I2—Cs1^i	110.19 (3)	I3^v—Cs1—I3^iii	105.08 (3)
I2^i—Cs1—I2	88.99 (2)	I3^v—Cs1—I4^vi	61.150 (19)
I2—Cs1—Cs1^i	42.878 (17)	I3^iv—Cs1—I4^i	116.67 (2)
I2^i—Cs1—Cs1^i	46.110 (14)	I3^v—Cs1—I4^i	98.65 (2)
I2^i—Cs1—I4^i	63.21 (2)	I3^iii—Cs1—I4^i	72.10 (2)
I2^i—Cs1—I4^vi	102.497 (18)	I3^iii—Cs1—I4^vi	72.27 (3)
I1^ii—Cs1—I2	64.13 (2)	I3^iv—Cs1—I4^vi	135.01 (4)
I1^i—Cs1—I2	68.24 (3)	I4^i—Cs1—I2	105.902 (18)
I1—Cs1—I2^i	71.859 (16)	I4^iii—Cs1—I2	124.81 (2)
I1—Cs1—I2	41.88 (2)	I4^vi—Cs1—I2	100.98 (2)
I1^i—Cs1—I2^i	42.931 (18)	I4^iii—Cs1—I2^i	140.004 (16)
I1^ii—Cs1—I2^i	116.20 (3)	I4^iii—Cs1—Cs1^i	158.88 (4)
I1^i—Cs1—Cs1^i	40.052 (16)	I4^i—Cs1—Cs1^i	83.73 (2)
I1—Cs1—Cs1^i	41.53 (2)	I4^vi—Cs1—Cs1^i	106.532 (18)
I1^ii—Cs1—Cs1^i	89.19 (3)	I4^iii—Cs1—I1^ii	70.12 (3)
I1^i—Cs1—I1^ii	73.29 (2)	I4^iii—Cs1—I1^i	125.10 (2)
I1—Cs1—I1^ii	105.94 (3)	I4^iii—Cs1—I3^iii	52.29 (2)
I1—Cs1—I1^i	81.58 (3)	I4^iii—Cs1—I3^iv	63.860 (18)
I1^i—Cs1—I3^iii	119.90 (2)	I4^iii—Cs1—I3^v	73.707 (17)
I1—Cs1—I3^iii	135.17 (3)	I4^iii—Cs1—I4^vi	92.11 (3)
I1—Cs1—I3^iv	147.69 (3)	I4^i—Cs1—I4^vi	39.937 (18)
I1—Cs1—I3^v	73.879 (15)	I4^iii—Cs1—I4^i	117.33 (3)
I1—Cs1—I4^i	64.05 (2)	I2—I1—Cs1^viii	103.15 (2)
I1^i—Cs1—I4^vi	141.317 (17)	I2—I1—Cs1	76.69 (2)
I1—Cs1—I4^vi	68.48 (3)	I2—I1—Cs1^i	69.64 (3)
I1^i—Cs1—I4^i	105.17 (2)	Cs1—I1—Cs1^viii	100.93 (3)
I1—Cs1—I4^iii	147.32 (2)	Cs1—I1—Cs1^i	98.42 (3)
I1^ii—Cs1—I4^i	169.91 (2)	Cs1^i—I1—Cs1^viii	157.13 (3)
I1^ii—Cs1—I4^vi	137.258 (17)	I2—I3—Cs1^ix	106.00 (2)
I3^v—Cs1—I2	67.13 (2)	I2—I3—Cs1^x	125.92 (3)
I3^iii—Cs1—I2^i	96.92 (2)	I2—I3—Cs1^v	102.25 (3)
I3^iv—Cs1—I2^i	80.098 (15)	Cs1^x—I3—Cs1^v	99.581 (11)
I3^iii—Cs1—I2	171.82 (3)	Cs1^v—I3—Cs1^ix	101.52 (2)
I3^v—Cs1—I2^i	145.590 (16)	Cs1^x—I3—Cs1^ix	117.11 (3)
I3^iv—Cs1—I2	124.01 (4)	Cs1^i—I4—Cs1^xi	140.064 (19)
I3^iv—Cs1—Cs1^i	106.63 (3)	Cs1^ix—I4—Cs1^xi	95.08 (4)
I3^iii—Cs1—Cs1^i	142.700 (18)	Cs1^ix—I4—Cs1^i	99.852 (19)
I3^v—Cs1—Cs1^i	106.34 (2)	I4^vii—I4—Cs1^xi	66.95 (4)
I3^iv—Cs1—I1^ii	72.265 (19)	I4^vii—I4—Cs1^ix	112.17 (5)
I3^iii—Cs1—I1^ii	117.52 (2)	I4^vii—I4—Cs1^i	73.11 (3)

Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, −y+3/2, z+1/2; (iii) x+1, −y+3/2, z+1/2; (iv) −x+1, y+1/2, −z+3/2; (v) −x+1, −y+1, −z+1; (vi) x+1, y, z; (vii) −x, −y+2, −z+1; (viii) x, −y+3/2, z−1/2; (ix) x−1, −y+3/2, z−1/2; (x) −x+1, y−1/2, −z+3/2; (xi) x−1, y, z.

dicesium octaiodide (CsI4_1p65GPa)

Crystal data

CsI4	F(000) = 1068
Mr = 640.51	Dx = 5.131 Mg m^−3
Monoclinic, P21/c	Synchrotron radiation, λ = 0.41077 Å
a = 9.842 (3) Å	Cell parameters from 1443 reflections
b = 8.7061 (3) Å	θ = 2.4–21.2°
c = 10.7364 (10) Å	µ = 4.39 mm^−1
β = 115.68 (2)°	T = 296 K
V = 829.1 (3) Å^3	Plate, dark red
Z = 4	0.04 × 0.02 × 0.01 mm

Data collection

Esperanto-CrysAlisPro-abstract goniometer imported esperanto images diffractometer	1051 independent reflections
Radiation source: undulator, ID15B, ESRF	964 reflections with I > 2σ(I)
Synchrotron monochromator	Rint = 0.016
Detector resolution: 13.3333 pixels mm^-1	θmax = 20.0°, θmin = 2.2°
phi scan	h = −6→7
Absorption correction: multi-scan CrysAlisPro 1.171.40.67a (Rigaku Oxford Diffraction, 2019) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −12→11
Tmin = 0.219, Tmax = 1.000	l = −16→16
1939 measured reflections

Refinement

Refinement on F^2	46 parameters
Least-squares matrix: full	0 restraints
R[F^2 > 2σ(F^2)] = 0.052	w = 1/[σ^2(Fo^2) + (0.126P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.171	(Δ/σ)max < 0.001
S = 1.16	Δρmax = 1.52 e Å^−3
1051 reflections	Δρmin = −1.32 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
I2	0.3851 (2)	0.71207 (8)	0.39450 (7)	0.0372 (9)
Cs1	0.7789 (2)	0.87791 (8)	0.69276 (7)	0.0400 (9)
I1	0.5616 (3)	0.90747 (9)	0.31366 (8)	0.0403 (9)
I3	0.1738 (2)	0.50610 (9)	0.45230 (9)	0.0406 (9)
I4	1.0515 (2)	0.64647 (9)	0.99757 (8)	0.0412 (9)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I2	0.050 (3)	0.0322 (4)	0.0349 (4)	0.0028 (4)	0.0240 (8)	−0.00152 (19)
Cs1	0.048 (3)	0.0397 (5)	0.0361 (4)	0.0043 (4)	0.0222 (8)	0.0030 (2)
I1	0.046 (3)	0.0432 (5)	0.0392 (5)	−0.0016 (6)	0.0260 (9)	0.0027 (2)
I3	0.051 (3)	0.0315 (5)	0.0467 (5)	−0.0002 (5)	0.0278 (8)	0.0036 (2)
I4	0.051 (3)	0.0343 (5)	0.0421 (5)	0.0057 (5)	0.0236 (9)	0.0022 (2)

Geometric parameters (Å, º)

I2—Cs1^i	3.8620 (13)	Cs1—I3^iii	3.809 (3)
I2—Cs1	4.075 (3)	Cs1—I3^iv	3.8008 (10)
I2—I1	2.823 (2)	Cs1—I3^v	3.8011 (12)
I2—I3	3.008 (2)	Cs1—I4^vi	4.063 (2)
Cs1—Cs1^i	5.665 (4)	Cs1—I4	3.7893 (19)
Cs1—I1^i	3.811 (3)	Cs1—I4^vii	3.9228 (18)
Cs1—I1	3.6963 (16)	I4—I4^viii	2.753 (2)
Cs1—I1^ii	3.852 (2)
Cs1^i—I2—Cs1	91.05 (4)	I3^iii—Cs1—I1^i	119.59 (4)
I1—I2—Cs1^i	67.46 (5)	I3^v—Cs1—I1^i	133.37 (6)
I1—I2—Cs1	61.69 (4)	I3^iii—Cs1—I1^ii	117.65 (3)
I1—I2—I3	174.44 (6)	I3^iv—Cs1—I3^v	133.28 (2)
I3—I2—Cs1	123.81 (3)	I3^iv—Cs1—I3^iii	62.98 (5)
I3—I2—Cs1^i	110.33 (6)	I3^v—Cs1—I3^iii	105.40 (5)
I2^i—Cs1—I2	88.95 (4)	I3^iv—Cs1—I4^vii	116.90 (3)
I2—Cs1—Cs1^i	42.97 (3)	I3^iii—Cs1—I4^vi	72.46 (5)
I2^i—Cs1—Cs1^i	45.98 (3)	I3^iii—Cs1—I4^vii	72.14 (4)
I2^i—Cs1—I4^vii	63.27 (4)	I3^v—Cs1—I4^vii	98.94 (4)
I2^i—Cs1—I4^vi	102.89 (3)	I3^v—Cs1—I4^vi	61.13 (3)
I1^ii—Cs1—I2	63.80 (4)	I3^iv—Cs1—I4^vi	135.32 (6)
I1^i—Cs1—I2	68.29 (5)	I4^vii—Cs1—I2	106.04 (3)
I1—Cs1—I2^i	71.76 (3)	I4—Cs1—I2	124.52 (4)
I1—Cs1—I2	42.26 (4)	I4^vi—Cs1—I2	101.06 (4)
I1^i—Cs1—I2^i	43.17 (3)	I4—Cs1—I2^i	140.00 (3)
I1^ii—Cs1—I2^i	116.32 (6)	I4—Cs1—Cs1^i	158.41 (6)
I1—Cs1—Cs1^i	41.78 (4)	I4^vii—Cs1—Cs1^i	83.81 (3)
I1^ii—Cs1—Cs1^i	89.12 (6)	I4^vi—Cs1—Cs1^i	106.86 (3)
I1^i—Cs1—Cs1^i	40.25 (3)	I4—Cs1—I1^i	124.35 (4)
I1^i—Cs1—I1^ii	73.15 (4)	I4—Cs1—I1^ii	69.79 (5)
I1—Cs1—I1^ii	105.98 (6)	I4—Cs1—I3^iii	52.62 (4)
I1—Cs1—I1^i	82.03 (5)	I4—Cs1—I3^iv	63.70 (3)
I1—Cs1—I3^iv	147.64 (6)	I4—Cs1—I3^v	73.71 (3)
I1—Cs1—I3^iii	135.01 (5)	I4—Cs1—I4^vi	92.24 (6)
I1—Cs1—I3^v	74.05 (3)	I4^vii—Cs1—I4^vi	40.28 (3)
I1—Cs1—I4^vii	63.80 (4)	I4—Cs1—I4^vii	117.71 (5)
I1^i—Cs1—I4^vi	142.02 (3)	I2—I1—Cs1^vi	102.73 (4)
I1—Cs1—I4^vi	68.40 (5)	I2—I1—Cs1	76.05 (4)
I1^i—Cs1—I4^vii	105.53 (4)	I2—I1—Cs1^i	69.37 (6)
I1—Cs1—I4	147.49 (4)	Cs1—I1—Cs1^vi	100.69 (6)
I1^ii—Cs1—I4^vii	169.68 (4)	Cs1—I1—Cs1^i	97.97 (5)
I1^ii—Cs1—I4^vi	136.65 (3)	Cs1^i—I1—Cs1^vi	157.27 (5)
I3^iv—Cs1—I2	123.62 (6)	I2—I3—Cs1^ix	105.59 (4)
I3^iii—Cs1—I2^i	96.84 (4)	I2—I3—Cs1^x	125.92 (6)
I3^iv—Cs1—I2^i	80.13 (3)	I2—I3—Cs1^v	102.79 (5)
I3^iii—Cs1—I2	172.10 (5)	Cs1^x—I3—Cs1^v	99.73 (2)
I3^v—Cs1—I2^i	145.70 (3)	Cs1^v—I3—Cs1^ix	101.59 (4)
I3^v—Cs1—I2	67.05 (4)	Cs1^x—I3—Cs1^ix	117.02 (5)
I3^iv—Cs1—Cs1^i	106.34 (5)	Cs1^xi—I4—Cs1^ii	139.72 (3)
I3^iii—Cs1—Cs1^i	142.53 (3)	Cs1—I4—Cs1^ii	95.43 (6)
I3^v—Cs1—Cs1^i	106.42 (4)	Cs1—I4—Cs1^xi	99.73 (3)
I3^iv—Cs1—I1^ii	72.32 (3)	I4^viii—I4—Cs1^ii	67.12 (6)
I3^iv—Cs1—I1^i	66.36 (4)	I4^viii—I4—Cs1	112.35 (8)
I3^v—Cs1—I1^ii	75.83 (3)	I4^viii—I4—Cs1^xi	72.59 (5)

Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, −y+3/2, z+1/2; (iii) x+1, −y+3/2, z+1/2; (iv) −x+1, y+1/2, −z+3/2; (v) −x+1, −y+1, −z+1; (vi) x, −y+3/2, z−1/2; (vii) −x+2, y+1/2, −z+3/2; (viii) −x+2, −y+1, −z+2; (ix) x−1, −y+3/2, z−1/2; (x) −x+1, y−1/2, −z+3/2; (xi) −x+2, y−1/2, −z+3/2.

dicesium octaiodide (CsI4_1p97GPa)

Crystal data

CsI4	F(000) = 1068
Mr = 640.51	Dx = 5.204 Mg m^−3
Monoclinic, P21/c	Synchrotron radiation, λ = 0.41077 Å
a = 9.788 (2) Å	Cell parameters from 1228 reflections
b = 8.6889 (3) Å	θ = 2.5–20.8°
c = 10.6600 (7) Å	µ = 4.45 mm^−1
β = 115.607 (17)°	T = 296 K
V = 817.6 (2) Å^3	Plate, dark red
Z = 4	0.04 × 0.02 × 0.01 mm

Data collection

Esperanto-CrysAlisPro-abstract goniometer imported esperanto images diffractometer	827 independent reflections
Radiation source: undulator, ID15B, ESRF	768 reflections with I > 2σ(I)
Synchrotron monochromator	Rint = 0.022
Detector resolution: 13.3333 pixels mm^-1	θmax = 17.1°, θmin = 2.2°
phi scan	h = −6→7
Absorption correction: multi-scan CrysAlisPro 1.171.41.93a (Rigaku Oxford Diffraction, 2020) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −11→11
Tmin = 0.643, Tmax = 1.000	l = −15→15
1592 measured reflections

Refinement

Refinement on F^2	46 parameters
Least-squares matrix: full	0 restraints
R[F^2 > 2σ(F^2)] = 0.023	w = 1/[σ^2(Fo^2) + (0.0504P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.071	(Δ/σ)max = 0.001
S = 1.05	Δρmax = 0.56 e Å^−3
827 reflections	Δρmin = −0.45 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
I2	0.38551 (12)	0.71304 (5)	0.39475 (4)	0.0382 (5)
Cs1	0.77861 (12)	0.87804 (5)	0.69228 (4)	0.0409 (5)
I1	0.56253 (14)	0.90873 (6)	0.31262 (5)	0.0415 (5)
I3	0.17396 (13)	0.50523 (5)	0.45220 (5)	0.0406 (5)
I4	1.05135 (12)	0.64705 (5)	0.99782 (5)	0.0398 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I2	0.0470 (14)	0.0360 (3)	0.0309 (2)	0.0029 (3)	0.0162 (4)	−0.00179 (12)
Cs1	0.0460 (15)	0.0423 (3)	0.0318 (2)	0.0041 (2)	0.0145 (4)	0.00289 (12)
I1	0.0450 (16)	0.0459 (3)	0.0344 (2)	−0.0018 (3)	0.0181 (5)	0.00239 (15)
I3	0.0449 (14)	0.0358 (3)	0.0416 (3)	−0.0009 (3)	0.0193 (5)	0.00317 (14)
I4	0.0407 (15)	0.0384 (3)	0.0374 (3)	0.0050 (3)	0.0141 (5)	0.00227 (14)

Geometric parameters (Å, º)

I2—Cs1^i	3.8442 (8)	Cs1—I3^iii	3.7965 (17)
I2—Cs1	4.0462 (16)	Cs1—I3^iv	3.7787 (6)
I2—I1	2.8235 (12)	Cs1—I3^v	3.7810 (7)
I2—I3	3.0032 (12)	Cs1—I4^vi	4.0319 (15)
Cs1—Cs1^i	5.632 (2)	Cs1—I4	3.7746 (11)
Cs1—I1^i	3.7995 (17)	Cs1—I4^vii	3.9058 (10)
Cs1—I1	3.6776 (9)	I4—I4^viii	2.7538 (13)
Cs1—I1^ii	3.8305 (12)
Cs1^i—I2—Cs1	91.05 (2)	I3^iii—Cs1—I1^i	119.49 (2)
I1—I2—Cs1^i	67.48 (3)	I3^v—Cs1—I1^i	133.30 (4)
I1—I2—Cs1	61.74 (3)	I3^iii—Cs1—I1^ii	117.75 (2)
I1—I2—I3	174.25 (3)	I3^iv—Cs1—I3^v	133.051 (15)
I3—I2—Cs1	123.99 (2)	I3^iv—Cs1—I3^iii	62.95 (3)
I3—I2—Cs1^i	110.60 (4)	I3^v—Cs1—I3^iii	105.47 (3)
I2^i—Cs1—I2	88.95 (2)	I3^iv—Cs1—I4^vii	116.75 (2)
I2—Cs1—Cs1^i	43.036 (18)	I3^iii—Cs1—I4^vi	72.37 (3)
I2^i—Cs1—Cs1^i	45.914 (15)	I3^iii—Cs1—I4^vii	71.96 (3)
I2^i—Cs1—I4^vii	63.19 (2)	I3^v—Cs1—I4^vii	99.26 (2)
I2^i—Cs1—I4^vi	103.08 (2)	I3^v—Cs1—I4^vi	61.170 (19)
I1^ii—Cs1—I2	63.66 (2)	I3^iv—Cs1—I4^vi	135.22 (4)
I1^i—Cs1—I2	68.26 (3)	I4^vii—Cs1—I2	106.230 (19)
I1—Cs1—I2^i	71.688 (16)	I4—Cs1—I2	124.49 (2)
I1—Cs1—I2	42.55 (2)	I4^vi—Cs1—I2	101.22 (2)
I1^i—Cs1—I2^i	43.350 (19)	I4—Cs1—I2^i	139.966 (16)
I1^ii—Cs1—I2^i	116.64 (3)	I4—Cs1—Cs1^i	158.35 (3)
I1—Cs1—Cs1^i	41.95 (2)	I4^vii—Cs1—Cs1^i	83.86 (2)
I1^ii—Cs1—Cs1^i	89.27 (3)	I4^vi—Cs1—Cs1^i	107.12 (2)
I1^i—Cs1—Cs1^i	40.319 (17)	I4—Cs1—I1^i	124.11 (2)
I1^i—Cs1—I1^ii	73.30 (2)	I4—Cs1—I1^ii	69.64 (3)
I1—Cs1—I1^ii	106.11 (3)	I4—Cs1—I3^iii	52.74 (2)
I1—Cs1—I1^i	82.27 (3)	I4—Cs1—I3^iv	63.616 (19)
I1—Cs1—I3^iv	147.72 (3)	I4—Cs1—I3^v	73.596 (18)
I1—Cs1—I3^iii	134.73 (3)	I4—Cs1—I4^vi	92.08 (3)
I1—Cs1—I3^v	74.279 (16)	I4^vii—Cs1—I4^vi	40.559 (19)
I1—Cs1—I4^vii	63.71 (2)	I4—Cs1—I4^vii	117.70 (3)
I1^i—Cs1—I4^vi	142.432 (18)	I2—I1—Cs1^vi	102.35 (2)
I1—Cs1—I4^vi	68.39 (3)	I2—I1—Cs1	75.71 (2)
I1^i—Cs1—I4^vii	105.67 (2)	I2—I1—Cs1^i	69.17 (3)
I1—Cs1—I4	147.57 (2)	Cs1—I1—Cs1^vi	100.56 (3)
I1^ii—Cs1—I4^vii	169.68 (2)	Cs1—I1—Cs1^i	97.73 (3)
I1^ii—Cs1—I4^vi	136.152 (18)	Cs1^i—I1—Cs1^vi	157.20 (3)
I3^iv—Cs1—I2	123.56 (4)	I2—I3—Cs1^ix	105.41 (3)
I3^iii—Cs1—I2^i	96.72 (2)	I2—I3—Cs1^x	125.71 (3)
I3^iv—Cs1—I2^i	80.160 (17)	I2—I3—Cs1^v	103.27 (3)
I3^iii—Cs1—I2	172.23 (3)	Cs1^x—I3—Cs1^v	99.640 (12)
I3^v—Cs1—I2^i	145.879 (17)	Cs1^v—I3—Cs1^ix	101.77 (2)
I3^v—Cs1—I2	67.12 (2)	Cs1^x—I3—Cs1^ix	117.05 (3)
I3^iv—Cs1—Cs1^i	106.29 (3)	Cs1^xi—I4—Cs1^ii	139.440 (19)
I3^iii—Cs1—Cs1^i	142.35 (2)	Cs1—I4—Cs1^ii	95.38 (4)
I3^v—Cs1—Cs1^i	106.60 (2)	Cs1—I4—Cs1^xi	99.882 (19)
I3^iv—Cs1—I1^ii	72.581 (19)	I4^viii—I4—Cs1^ii	67.26 (4)
I3^iv—Cs1—I1^i	66.26 (3)	I4^viii—I4—Cs1	112.38 (5)
I3^v—Cs1—I1^ii	75.30 (2)	I4^viii—I4—Cs1^xi	72.18 (3)

Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, −y+3/2, z+1/2; (iii) x+1, −y+3/2, z+1/2; (iv) −x+1, y+1/2, −z+3/2; (v) −x+1, −y+1, −z+1; (vi) x, −y+3/2, z−1/2; (vii) −x+2, y+1/2, −z+3/2; (viii) −x+2, −y+1, −z+2; (ix) x−1, −y+3/2, z−1/2; (x) −x+1, y−1/2, −z+3/2; (xi) −x+2, y−1/2, −z+3/2.

dicesium octaiodide (CsI4_2p32GPa)

Crystal data

CsI4	F(000) = 1068
Mr = 640.51	Dx = 5.304 Mg m^−3
Monoclinic, P21/c	Synchrotron radiation, λ = 0.41077 Å
a = 9.7195 (12) Å	Cell parameters from 1368 reflections
b = 8.6486 (2) Å	θ = 2.2–21.4°
c = 10.5900 (4) Å	µ = 4.54 mm^−1
β = 115.709 (9)°	T = 296 K
V = 802.07 (12) Å^3	Plate, dark red
Z = 4	0.04 × 0.02 × 0.01 mm

Data collection

Esperanto-CrysAlisPro-abstract goniometer imported esperanto images diffractometer	1023 independent reflections
Radiation source: undulator, ID15B, ESRF	950 reflections with I > 2σ(I)
Synchrotron monochromator	Rint = 0.014
Detector resolution: 13.3333 pixels mm^-1	θmax = 21.3°, θmin = 2.2°
phi scan	h = −6→7
Absorption correction: multi-scan CrysAlisPro 1.171.41.93a (Rigaku Oxford Diffraction, 2020) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −12→11
Tmin = 0.895, Tmax = 1.000	l = −16→15
1880 measured reflections

Refinement

Refinement on F^2	46 parameters
Least-squares matrix: full	0 restraints
R[F^2 > 2σ(F^2)] = 0.019	w = 1/[σ^2(Fo^2) + (0.0357P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.059	(Δ/σ)max = 0.001
S = 1.13	Δρmax = 0.68 e Å^−3
1023 reflections	Δρmin = −0.80 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
I2	0.38622 (9)	0.71360 (3)	0.39521 (3)	0.0295 (3)
Cs1	0.77864 (9)	0.87866 (4)	0.69178 (3)	0.0332 (3)
I1	0.56313 (10)	0.90966 (4)	0.31141 (3)	0.0331 (4)
I3	0.17400 (9)	0.50392 (4)	0.45229 (4)	0.0324 (3)
I4	1.05177 (9)	0.64776 (4)	0.99818 (3)	0.0320 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I2	0.0325 (10)	0.02798 (17)	0.02840 (15)	0.00235 (17)	0.0137 (3)	−0.00168 (8)
Cs1	0.0358 (10)	0.03355 (18)	0.02884 (15)	0.00332 (18)	0.0126 (3)	0.00235 (8)
I1	0.0322 (11)	0.0374 (2)	0.03105 (17)	−0.0019 (2)	0.0150 (3)	0.00226 (10)
I3	0.0331 (10)	0.02709 (18)	0.03836 (18)	−0.0007 (2)	0.0168 (3)	0.00292 (9)
I4	0.0303 (11)	0.02941 (19)	0.03465 (17)	0.00532 (18)	0.0125 (3)	0.00232 (9)

Geometric parameters (Å, º)

I2—Cs1^i	3.8172 (6)	Cs1—I3^iii	3.7697 (11)
I2—Cs1	4.0071 (10)	Cs1—I3^iv	3.7533 (4)
I2—I1	2.8184 (9)	Cs1—I3^v	3.7547 (5)
I2—I3	2.9984 (8)	Cs1—I4^vi	4.0032 (10)
Cs1—Cs1^i	5.5816 (14)	Cs1—I4	3.7537 (7)
Cs1—I1^i	3.7803 (12)	Cs1—I4^vii	3.8803 (7)
Cs1—I1	3.6558 (6)	I4—I4^viii	2.7532 (9)
Cs1—I1^ii	3.8095 (8)
Cs1^i—I2—Cs1	90.987 (16)	I3^iii—Cs1—I1^ii	117.770 (14)
I1—I2—Cs1	61.911 (18)	I3^iv—Cs1—I1^i	66.024 (18)
I1—I2—Cs1^i	67.53 (2)	I3^iii—Cs1—I1^i	119.267 (15)
I1—I2—I3	173.92 (2)	I3^iv—Cs1—I3^iii	62.95 (2)
I3—I2—Cs1^i	110.73 (3)	I3^iv—Cs1—I3^v	132.782 (11)
I3—I2—Cs1	124.167 (13)	I3^v—Cs1—I3^iii	105.608 (19)
I2^i—Cs1—I2	89.013 (16)	I3^iii—Cs1—I4^vii	71.968 (18)
I2—Cs1—Cs1^i	43.140 (12)	I3^iv—Cs1—I4^vii	116.928 (15)
I2^i—Cs1—Cs1^i	45.872 (11)	I3^iv—Cs1—I4	63.437 (13)
I2^i—Cs1—I4^vi	103.376 (14)	I3^iii—Cs1—I4^vi	72.440 (19)
I2^i—Cs1—I4^vii	63.196 (15)	I3^iv—Cs1—I4^vi	135.33 (3)
I1—Cs1—I2	42.854 (15)	I3^v—Cs1—I4^vi	61.062 (14)
I1—Cs1—I2^i	71.727 (11)	I3^v—Cs1—I4^vii	99.402 (17)
I1^i—Cs1—I2^i	43.547 (13)	I4^vii—Cs1—I2	106.339 (13)
I1^i—Cs1—I2	68.381 (19)	I4—Cs1—I2^i	139.952 (11)
I1^ii—Cs1—I2	63.494 (15)	I4—Cs1—I2	124.316 (15)
I1^ii—Cs1—I2^i	116.82 (2)	I4^vi—Cs1—I2	101.273 (15)
I1—Cs1—Cs1^i	42.208 (15)	I4—Cs1—Cs1^i	158.16 (3)
I1^ii—Cs1—Cs1^i	89.32 (2)	I4^vi—Cs1—Cs1^i	107.370 (14)
I1^i—Cs1—Cs1^i	40.519 (12)	I4^vii—Cs1—Cs1^i	83.890 (14)
I1—Cs1—I1^ii	106.23 (2)	I4—Cs1—I1^ii	69.452 (18)
I1—Cs1—I1^i	82.727 (18)	I4—Cs1—I1^i	123.680 (16)
I1^i—Cs1—I1^ii	73.271 (15)	I4—Cs1—I3^iii	52.883 (15)
I1—Cs1—I3^v	74.308 (11)	I4—Cs1—I3^v	73.563 (12)
I1—Cs1—I3^iv	147.93 (2)	I4—Cs1—I4^vi	92.00 (2)
I1—Cs1—I3^iii	134.55 (2)	I4—Cs1—I4^vii	117.84 (2)
I1—Cs1—I4	147.543 (15)	I4^vii—Cs1—I4^vi	40.844 (14)
I1^ii—Cs1—I4^vi	135.678 (13)	I2—I1—Cs1	75.235 (16)
I1^i—Cs1—I4^vi	142.984 (12)	I2—I1—Cs1^vi	102.092 (17)
I1—Cs1—I4^vii	63.513 (15)	I2—I1—Cs1^i	68.92 (2)
I1—Cs1—I4^vi	68.294 (19)	Cs1—I1—Cs1^vi	100.57 (2)
I1^i—Cs1—I4^vii	105.912 (14)	Cs1—I1—Cs1^i	97.273 (18)
I1^ii—Cs1—I4^vii	169.574 (15)	Cs1^i—I1—Cs1^vi	157.197 (19)
I3^iv—Cs1—I2	123.39 (3)	I2—I3—Cs1^v	103.58 (2)
I3^v—Cs1—I2^i	145.964 (12)	I2—I3—Cs1^ix	105.161 (17)
I3^iv—Cs1—I2^i	80.297 (12)	I2—I3—Cs1^x	125.57 (2)
I3^v—Cs1—I2	67.067 (16)	Cs1^x—I3—Cs1^ix	117.05 (2)
I3^iii—Cs1—I2	172.342 (19)	Cs1^v—I3—Cs1^ix	101.873 (17)
I3^iii—Cs1—I2^i	96.643 (16)	Cs1^x—I3—Cs1^v	99.815 (9)
I3^iv—Cs1—Cs1^i	106.25 (2)	Cs1—I4—Cs1^ii	95.49 (2)
I3^iii—Cs1—Cs1^i	142.242 (13)	Cs1^xi—I4—Cs1^ii	139.156 (14)
I3^v—Cs1—Cs1^i	106.678 (17)	Cs1—I4—Cs1^xi	99.852 (13)
I3^v—Cs1—I1^i	133.26 (3)	I4^viii—I4—Cs1^ii	67.18 (3)
I3^v—Cs1—I1^ii	74.950 (14)	I4^viii—I4—Cs1	112.35 (3)
I3^iv—Cs1—I1^ii	72.577 (13)	I4^viii—I4—Cs1^xi	71.97 (2)

Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, −y+3/2, z+1/2; (iii) x+1, −y+3/2, z+1/2; (iv) −x+1, y+1/2, −z+3/2; (v) −x+1, −y+1, −z+1; (vi) x, −y+3/2, z−1/2; (vii) −x+2, y+1/2, −z+3/2; (viii) −x+2, −y+1, −z+2; (ix) x−1, −y+3/2, z−1/2; (x) −x+1, y−1/2, −z+3/2; (xi) −x+2, y−1/2, −z+3/2.

dicesium octaiodide (CsI4_2p74GPa)

Crystal data

CsI4	F(000) = 1068
Mr = 640.51	Dx = 5.430 Mg m^−3
Monoclinic, P21/c	Synchrotron radiation, λ = 0.41077 Å
a = 9.6370 (13) Å	Cell parameters from 1369 reflections
b = 8.6017 (2) Å	θ = 1.9–21.5°
c = 10.4967 (4) Å	µ = 4.65 mm^−1
β = 115.788 (9)°	T = 296 K
V = 783.46 (12) Å^3	Plate, dark red
Z = 4	0.04 × 0.02 × 0.01 mm

Data collection

Esperanto-CrysAlisPro-abstract goniometer imported esperanto images diffractometer	1027 independent reflections
Radiation source: undulator, ID15B, ESRF	967 reflections with I > 2σ(I)
Synchrotron monochromator	Rint = 0.020
Detector resolution: 13.3333 pixels mm^-1	θmax = 21.5°, θmin = 1.9°
phi scan	h = −6→7
Absorption correction: multi-scan CrysAlisPro 1.171.41.93a (Rigaku Oxford Diffraction, 2020) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −12→11
Tmin = 0.725, Tmax = 1.000	l = −16→15
1897 measured reflections

Refinement

Refinement on F^2	46 parameters
Least-squares matrix: full	0 restraints
R[F^2 > 2σ(F^2)] = 0.023	w = 1/[σ^2(Fo^2) + (0.0403P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.061	(Δ/σ)max = 0.001
S = 1.06	Δρmax = 0.81 e Å^−3
1027 reflections	Δρmin = −0.90 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
I2	0.38700 (9)	0.71457 (3)	0.39579 (3)	0.0274 (3)
Cs1	0.77848 (9)	0.87929 (3)	0.69139 (3)	0.0314 (3)
I1	0.56362 (10)	0.91120 (4)	0.31005 (3)	0.0307 (3)
I3	0.17388 (9)	0.50231 (4)	0.45208 (3)	0.0299 (3)
I4	1.05213 (9)	0.64846 (4)	0.99866 (3)	0.0300 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I2	0.0293 (9)	0.02730 (17)	0.02658 (15)	0.00179 (16)	0.0130 (3)	−0.00166 (8)
Cs1	0.0348 (9)	0.03185 (17)	0.02660 (15)	0.00319 (17)	0.0125 (3)	0.00209 (8)
I1	0.0292 (10)	0.03618 (19)	0.02832 (16)	−0.00201 (19)	0.0139 (3)	0.00184 (9)
I3	0.0298 (9)	0.02613 (18)	0.03540 (18)	−0.00071 (17)	0.0156 (3)	0.00270 (8)
I4	0.0284 (10)	0.02818 (18)	0.03220 (17)	0.00441 (17)	0.0120 (3)	0.00204 (8)

Geometric parameters (Å, º)

I2—Cs1^i	3.7836 (5)	Cs1—I3^iii	3.7380 (11)
I2—Cs1	3.9602 (10)	Cs1—I3^iv	3.7221 (5)
I2—I1	2.8108 (9)	Cs1—I3^v	3.7204 (4)
I2—I3	2.9928 (9)	Cs1—I4^vi	3.9682 (10)
Cs1—Cs1^i	5.5227 (14)	Cs1—I4	3.7282 (7)
Cs1—I1^i	3.7515 (11)	Cs1—I4^vii	3.8521 (7)
Cs1—I1	3.6295 (6)	I4—I4^viii	2.7492 (9)
Cs1—I1^ii	3.7850 (8)
Cs1^i—I2—Cs1	90.960 (16)	I3^v—Cs1—I1^i	65.863 (17)
I1—I2—Cs1	62.121 (18)	I3^v—Cs1—I1^ii	72.693 (13)
I1—I2—Cs1^i	67.491 (19)	I3^iv—Cs1—I1^i	133.23 (2)
I1—I2—I3	173.46 (2)	I3^iii—Cs1—I1^ii	117.927 (13)
I3—I2—Cs1^i	110.97 (3)	I3^v—Cs1—I3^iii	62.98 (2)
I3—I2—Cs1	124.421 (13)	I3^v—Cs1—I3^iv	132.442 (10)
I2^i—Cs1—I2	89.040 (16)	I3^iv—Cs1—I3^iii	105.697 (19)
I2^i—Cs1—Cs1^i	45.804 (10)	I3^v—Cs1—I4^vi	135.35 (2)
I2—Cs1—Cs1^i	43.236 (12)	I3^iii—Cs1—I4^vii	71.858 (17)
I2^i—Cs1—I1^ii	117.12 (2)	I3^iv—Cs1—I4^vii	99.548 (16)
I2^i—Cs1—I4^vi	103.646 (14)	I3^v—Cs1—I4^vii	117.086 (14)
I2—Cs1—I4^vi	101.356 (15)	I3^v—Cs1—I4	63.251 (12)
I2^i—Cs1—I4^vii	63.176 (15)	I3^iv—Cs1—I4^vi	60.946 (14)
I1^i—Cs1—I2^i	43.802 (13)	I3^iv—Cs1—I4	73.443 (12)
I1—Cs1—I2^i	71.655 (11)	I3^iii—Cs1—I4^vi	72.402 (19)
I1^ii—Cs1—I2	63.293 (15)	I4—Cs1—I2^i	140.001 (11)
I1^i—Cs1—I2	68.454 (19)	I4^vii—Cs1—I2	106.451 (13)
I1—Cs1—I2	43.199 (15)	I4—Cs1—I2	124.160 (15)
I1^i—Cs1—Cs1^i	40.730 (11)	I4^vi—Cs1—Cs1^i	107.627 (13)
I1—Cs1—Cs1^i	42.408 (15)	I4^vii—Cs1—Cs1^i	83.910 (14)
I1^ii—Cs1—Cs1^i	89.43 (2)	I4—Cs1—Cs1^i	158.04 (2)
I1—Cs1—I1^ii	106.35 (2)	I4—Cs1—I1^i	123.297 (16)
I1—Cs1—I1^i	83.138 (19)	I4—Cs1—I1^ii	69.272 (17)
I1^i—Cs1—I1^ii	73.313 (15)	I4—Cs1—I3^iii	53.104 (15)
I1—Cs1—I3^iii	134.23 (2)	I4—Cs1—I4^vi	91.84 (2)
I1—Cs1—I3^iv	74.460 (11)	I4—Cs1—I4^vii	117.94 (2)
I1—Cs1—I3^v	148.15 (2)	I4^vii—Cs1—I4^vi	41.131 (13)
I1^ii—Cs1—I4^vi	135.080 (12)	I2—I1—Cs1^i	68.71 (2)
I1^ii—Cs1—I4^vii	169.408 (14)	I2—I1—Cs1^vi	101.671 (16)
I1^i—Cs1—I4^vi	143.575 (12)	I2—I1—Cs1	74.679 (16)
I1^i—Cs1—I4^vii	106.190 (15)	Cs1—I1—Cs1^vi	100.47 (2)
I1—Cs1—I4^vi	68.230 (19)	Cs1—I1—Cs1^i	96.862 (19)
I1—Cs1—I4	147.546 (16)	Cs1^i—I1—Cs1^vi	157.133 (18)
I1—Cs1—I4^vii	63.281 (15)	I2—I3—Cs1^ix	125.25 (2)
I3^v—Cs1—I2	123.27 (3)	I2—I3—Cs1^x	104.942 (17)
I3^iii—Cs1—I2^i	96.526 (15)	I2—I3—Cs1^iv	104.01 (2)
I3^iv—Cs1—I2^i	146.058 (11)	Cs1^ix—I3—Cs1^x	117.02 (2)
I3^iii—Cs1—I2	172.442 (19)	Cs1^ix—I3—Cs1^iv	99.974 (8)
I3^v—Cs1—I2^i	80.517 (12)	Cs1^iv—I3—Cs1^x	102.122 (17)
I3^iv—Cs1—I2	67.084 (16)	Cs1^xi—I4—Cs1^ii	138.869 (13)
I3^v—Cs1—Cs1^i	106.29 (2)	Cs1—I4—Cs1^ii	95.52 (2)
I3^iv—Cs1—Cs1^i	106.807 (16)	Cs1—I4—Cs1^xi	99.888 (13)
I3^iii—Cs1—Cs1^i	142.064 (13)	I4^viii—I4—Cs1^ii	67.17 (3)
I3^iii—Cs1—I1^i	119.095 (15)	I4^viii—I4—Cs1	112.30 (3)
I3^iv—Cs1—I1^ii	74.479 (14)	I4^viii—I4—Cs1^xi	71.70 (2)

Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, −y+3/2, z+1/2; (iii) x+1, −y+3/2, z+1/2; (iv) −x+1, −y+1, −z+1; (v) −x+1, y+1/2, −z+3/2; (vi) x, −y+3/2, z−1/2; (vii) −x+2, y+1/2, −z+3/2; (viii) −x+2, −y+1, −z+2; (ix) −x+1, y−1/2, −z+3/2; (x) x−1, −y+3/2, z−1/2; (xi) −x+2, y−1/2, −z+3/2.

dicesium octaiodide (CsI4_3p05GPa)

Crystal data

CsI4	F(000) = 1068
Mr = 640.51	Dx = 5.463 Mg m^−3
Monoclinic, P21/c	Synchrotron radiation, λ = 0.41077 Å
a = 9.6171 (13) Å	Cell parameters from 1374 reflections
b = 8.5889 (2) Å	θ = 1.9–21.6°
c = 10.4726 (4) Å	µ = 4.68 mm^−1
β = 115.81 (1)°	T = 296 K
V = 778.75 (13) Å^3	Plate, dark red
Z = 4	0.04 × 0.02 × 0.01 mm

Data collection

Esperanto-CrysAlisPro-abstract goniometer imported esperanto images diffractometer	1028 independent reflections
Radiation source: undulator, ID15B, ESRF	971 reflections with I > 2σ(I)
Synchrotron monochromator	Rint = 0.021
Detector resolution: 13.3333 pixels mm^-1	θmax = 21.6°, θmin = 1.9°
phi scan	h = −6→7
Absorption correction: multi-scan CrysAlisPro 1.171.41.93a (Rigaku Oxford Diffraction, 2020) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −12→11
Tmin = 0.702, Tmax = 1.000	l = −16→15
1893 measured reflections

Refinement

Refinement on F^2	46 parameters
Least-squares matrix: full	0 restraints
R[F^2 > 2σ(F^2)] = 0.030	w = 1/[σ^2(Fo^2) + (0.0558P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.082	(Δ/σ)max = 0.001
S = 1.13	Δρmax = 1.15 e Å^−3
1028 reflections	Δρmin = −1.37 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
I2	0.38716 (10)	0.71480 (4)	0.39595 (4)	0.0274 (4)
Cs1	0.77851 (11)	0.87947 (4)	0.69126 (4)	0.0311 (4)
I1	0.56387 (12)	0.91154 (5)	0.30974 (4)	0.0301 (4)
I3	0.17398 (11)	0.50188 (4)	0.45203 (4)	0.0296 (4)
I4	1.05219 (11)	0.64871 (4)	0.99876 (4)	0.0300 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I2	0.0302 (11)	0.0271 (2)	0.02646 (19)	0.00165 (19)	0.0139 (3)	−0.00160 (9)
Cs1	0.0353 (11)	0.0314 (2)	0.0265 (2)	0.0028 (2)	0.0134 (3)	0.00199 (9)
I1	0.0289 (13)	0.0358 (2)	0.0282 (2)	−0.0021 (2)	0.0148 (4)	0.00173 (11)
I3	0.0301 (11)	0.0259 (2)	0.0350 (2)	−0.0008 (2)	0.0163 (4)	0.00250 (10)
I4	0.0299 (12)	0.0278 (2)	0.0320 (2)	0.0044 (2)	0.0131 (4)	0.00211 (10)

Geometric parameters (Å, º)

I2—Cs1^i	3.7748 (6)	Cs1—I3^iii	3.7306 (13)
I2—Cs1	3.9489 (12)	Cs1—I3^iv	3.7129 (6)
I2—I1	2.8097 (10)	Cs1—I3^v	3.7126 (5)
I2—I3	2.9901 (10)	Cs1—I4^vi	3.9587 (12)
Cs1—Cs1^i	5.5085 (17)	Cs1—I4	3.7210 (8)
Cs1—I1^i	3.7462 (13)	Cs1—I4^vii	3.8444 (9)
Cs1—I1	3.6220 (7)	I4—I4^viii	2.7490 (11)
Cs1—I1^ii	3.7786 (10)
Cs1^i—I2—Cs1	90.962 (19)	I3^v—Cs1—I1^i	65.80 (2)
I1—I2—Cs1	62.14 (2)	I3^v—Cs1—I1^ii	72.686 (16)
I1—I2—Cs1^i	67.52 (2)	I3^iv—Cs1—I1^i	133.18 (3)
I1—I2—I3	173.35 (3)	I3^iii—Cs1—I1^ii	117.962 (16)
I3—I2—Cs1^i	111.03 (3)	I3^v—Cs1—I3^iii	63.03 (3)
I3—I2—Cs1	124.500 (16)	I3^v—Cs1—I3^iv	132.345 (13)
I2^i—Cs1—I2	89.038 (19)	I3^iv—Cs1—I3^iii	105.74 (2)
I2^i—Cs1—Cs1^i	45.789 (13)	I3^v—Cs1—I4^vi	135.39 (3)
I2—Cs1—Cs1^i	43.249 (15)	I3^iii—Cs1—I4^vii	71.82 (2)
I2^i—Cs1—I1^ii	117.18 (3)	I3^iv—Cs1—I4^vii	99.62 (2)
I2^i—Cs1—I4^vi	103.735 (17)	I3^v—Cs1—I4^vii	117.142 (18)
I2—Cs1—I4^vi	101.395 (17)	I3^v—Cs1—I4	63.206 (15)
I2^i—Cs1—I4^vii	63.175 (17)	I3^iv—Cs1—I4^vi	60.932 (18)
I1^i—Cs1—I2^i	43.871 (16)	I3^iv—Cs1—I4	73.425 (14)
I1—Cs1—I2^i	71.646 (13)	I3^iii—Cs1—I4^vi	72.39 (2)
I1^ii—Cs1—I2	63.233 (18)	I4—Cs1—I2^i	140.007 (13)
I1^i—Cs1—I2	68.44 (2)	I4^vii—Cs1—I2	106.503 (15)
I1—Cs1—I2	43.300 (18)	I4—Cs1—I2	124.115 (17)
I1^i—Cs1—Cs1^i	40.765 (14)	I4^vi—Cs1—Cs1^i	107.718 (16)
I1—Cs1—Cs1^i	42.481 (17)	I4^vii—Cs1—Cs1^i	83.939 (16)
I1^ii—Cs1—Cs1^i	89.43 (3)	I4—Cs1—Cs1^i	157.98 (3)
I1—Cs1—I1^ii	106.39 (3)	I4—Cs1—I1^i	123.183 (19)
I1—Cs1—I1^i	83.25 (2)	I4—Cs1—I1^ii	69.22 (2)
I1^i—Cs1—I1^ii	73.304 (18)	I4—Cs1—I3^iii	53.160 (18)
I1—Cs1—I3^iii	134.15 (3)	I4—Cs1—I4^vi	91.81 (3)
I1—Cs1—I3^iv	74.490 (13)	I4—Cs1—I4^vii	117.97 (3)
I1—Cs1—I3^v	148.19 (3)	I4^vii—Cs1—I4^vi	41.223 (16)
I1^ii—Cs1—I4^vi	134.925 (15)	I2—I1—Cs1^i	68.61 (3)
I1^ii—Cs1—I4^vii	169.381 (17)	I2—I1—Cs1^vi	101.595 (19)
I1^i—Cs1—I4^vi	143.741 (14)	I2—I1—Cs1	74.56 (2)
I1^i—Cs1—I4^vii	106.269 (17)	Cs1—I1—Cs1^vi	100.46 (3)
I1—Cs1—I4^vi	68.21 (2)	Cs1—I1—Cs1^i	96.75 (2)
I1—Cs1—I4	147.549 (19)	Cs1^i—I1—Cs1^vi	157.10 (2)
I1—Cs1—I4^vii	63.234 (18)	I2—I3—Cs1^ix	125.19 (3)
I3^v—Cs1—I2	123.18 (3)	I2—I3—Cs1^x	104.88 (2)
I3^iii—Cs1—I2^i	96.507 (18)	I2—I3—Cs1^iv	104.16 (3)
I3^iv—Cs1—I2^i	146.084 (14)	Cs1^ix—I3—Cs1^x	116.97 (3)
I3^iii—Cs1—I2	172.48 (2)	Cs1^ix—I3—Cs1^iv	100.018 (10)
I3^v—Cs1—I2^i	80.566 (14)	Cs1^iv—I3—Cs1^x	102.17 (2)
I3^iv—Cs1—I2	67.081 (19)	Cs1^xi—I4—Cs1^ii	138.778 (16)
I3^v—Cs1—Cs1^i	106.26 (3)	Cs1—I4—Cs1^ii	95.55 (3)
I3^iv—Cs1—Cs1^i	106.83 (2)	Cs1—I4—Cs1^xi	99.894 (15)
I3^iii—Cs1—Cs1^i	142.033 (16)	I4^viii—I4—Cs1^ii	67.16 (3)
I3^iii—Cs1—I1^i	119.069 (17)	I4^viii—I4—Cs1	112.30 (4)
I3^iv—Cs1—I1^ii	74.344 (17)	I4^viii—I4—Cs1^xi	71.62 (2)

Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, −y+3/2, z+1/2; (iii) x+1, −y+3/2, z+1/2; (iv) −x+1, −y+1, −z+1; (v) −x+1, y+1/2, −z+3/2; (vi) x, −y+3/2, z−1/2; (vii) −x+2, y+1/2, −z+3/2; (viii) −x+2, −y+1, −z+2; (ix) −x+1, y−1/2, −z+3/2; (x) x−1, −y+3/2, z−1/2; (xi) −x+2, y−1/2, −z+3/2.

dicesium octaiodide (CsI4_3p33GPa)

Crystal data

CsI4	F(000) = 1068
Mr = 640.51	Dx = 5.515 Mg m^−3
Monoclinic, P21/c	Synchrotron radiation, λ = 0.41077 Å
a = 9.5973 (15) Å	Cell parameters from 1200 reflections
b = 8.5648 (2) Å	θ = 1.9–21.2°
c = 10.4284 (4) Å	µ = 4.72 mm^−1
β = 115.854 (11)°	T = 296 K
V = 771.40 (14) Å^3	Plate, dark red
Z = 4	0.04 × 0.02 × 0.01 mm

Data collection

Esperanto-CrysAlisPro-abstract goniometer imported esperanto images diffractometer	1002 independent reflections
Radiation source: undulator, ID15B, ESRF	926 reflections with I > 2σ(I)
Synchrotron monochromator	Rint = 0.023
Detector resolution: 13.3333 pixels mm^-1	θmax = 21.6°, θmin = 1.9°
phi scan	h = −7→6
Absorption correction: multi-scan CrysAlisPro 1.171.40.84a (Rigaku Oxford Diffraction, 2020) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −12→11
Tmin = 0.624, Tmax = 1.000	l = −15→16
1785 measured reflections

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Primary atom site location: dual
R[F^2 > 2σ(F^2)] = 0.036	w = 1/[σ^2(Fo^2) + (0.0707P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.101	(Δ/σ)max < 0.001
S = 1.10	Δρmax = 1.18 e Å^−3
1002 reflections	Δρmin = −1.06 e Å^−3
46 parameters

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
I2	0.38782 (14)	0.71531 (5)	0.39627 (5)	0.0251 (5)
Cs1	0.77876 (14)	0.87979 (6)	0.69114 (5)	0.0282 (5)
I1	0.56428 (16)	0.91217 (7)	0.30905 (5)	0.0281 (5)
I3	0.17429 (15)	0.50118 (6)	0.45199 (6)	0.0276 (5)
I4	1.05251 (14)	0.64913 (6)	0.99901 (5)	0.0274 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I2	0.0292 (15)	0.0236 (3)	0.0253 (3)	0.0020 (2)	0.0146 (4)	−0.00142 (12)
Cs1	0.0326 (15)	0.0277 (3)	0.0250 (2)	0.0031 (3)	0.0132 (4)	0.00203 (12)
I1	0.0289 (16)	0.0324 (3)	0.0267 (3)	−0.0018 (3)	0.0155 (5)	0.00160 (14)
I3	0.0306 (15)	0.0222 (3)	0.0336 (3)	−0.0003 (3)	0.0175 (5)	0.00275 (13)
I4	0.0280 (16)	0.0243 (3)	0.0309 (3)	0.0044 (3)	0.0136 (5)	0.00189 (14)

Geometric parameters (Å, º)

I2—Cs1^i	3.7605 (9)	Cs1—I3^iii	3.7206 (16)
I2—Cs1	3.9313 (16)	Cs1—I3^iv	3.6975 (7)
I2—I1	2.8073 (14)	Cs1—I3^v	3.6965 (8)
I2—I3	2.9899 (14)	Cs1—I4^vi	3.9459 (16)
Cs1—Cs1^i	5.492 (2)	Cs1—I4	3.7089 (11)
Cs1—I1^i	3.7427 (18)	Cs1—I4^vii	3.8309 (12)
Cs1—I1	3.6107 (9)	I4—I4^viii	2.7497 (14)
Cs1—I1^ii	3.7697 (14)
Cs1^i—I2—Cs1	91.09 (3)	I3^v—Cs1—I1^i	133.01 (4)
I1—I2—Cs1	62.19 (3)	I3^v—Cs1—I1^ii	74.11 (2)
I1—I2—Cs1^i	67.69 (3)	I3^iv—Cs1—I1^i	65.65 (3)
I1—I2—I3	173.11 (3)	I3^iii—Cs1—I1^ii	118.13 (2)
I3—I2—Cs1^i	110.96 (4)	I3^v—Cs1—I3^iii	105.78 (3)
I3—I2—Cs1	124.68 (2)	I3^v—Cs1—I3^iv	132.206 (17)
I2^i—Cs1—I2	88.91 (2)	I3^iv—Cs1—I3^iii	63.22 (4)
I2^i—Cs1—Cs1^i	45.704 (17)	I3^v—Cs1—I4^vi	60.93 (2)
I2—Cs1—Cs1^i	43.207 (18)	I3^iii—Cs1—I4^vii	71.74 (3)
I2^i—Cs1—I1^ii	117.12 (4)	I3^iv—Cs1—I4^vii	117.27 (2)
I2^i—Cs1—I4^vi	103.98 (2)	I3^v—Cs1—I4^vii	99.73 (3)
I2—Cs1—I4^vi	101.54 (2)	I3^v—Cs1—I4	73.399 (19)
I2^i—Cs1—I4^vii	63.27 (2)	I3^iv—Cs1—I4^vi	135.47 (4)
I1^i—Cs1—I2^i	43.94 (2)	I3^iv—Cs1—I4	63.20 (2)
I1—Cs1—I2^i	71.588 (18)	I3^iii—Cs1—I4^vi	72.27 (3)
I1^ii—Cs1—I2	63.05 (2)	I4—Cs1—I2^i	140.068 (18)
I1^i—Cs1—I2	68.34 (3)	I4^vii—Cs1—I2	106.591 (19)
I1—Cs1—I2	43.45 (2)	I4—Cs1—I2	124.08 (2)
I1^i—Cs1—Cs1^i	40.776 (18)	I4^vi—Cs1—Cs1^i	107.98 (2)
I1—Cs1—Cs1^i	42.61 (2)	I4^vii—Cs1—Cs1^i	84.06 (2)
I1^ii—Cs1—Cs1^i	89.30 (4)	I4—Cs1—Cs1^i	157.85 (4)
I1—Cs1—I1^ii	106.34 (4)	I4—Cs1—I1^i	123.02 (3)
I1—Cs1—I1^i	83.38 (3)	I4—Cs1—I1^ii	69.25 (3)
I1^i—Cs1—I1^ii	73.18 (2)	I4—Cs1—I3^iii	53.23 (2)
I1—Cs1—I3^iii	134.00 (4)	I4—Cs1—I4^vi	91.66 (4)
I1—Cs1—I3^iv	148.18 (4)	I4—Cs1—I4^vii	117.97 (3)
I1—Cs1—I3^v	74.539 (18)	I4^vii—Cs1—I4^vi	41.38 (2)
I1^ii—Cs1—I4^vi	134.68 (2)	I2—I1—Cs1^i	68.37 (4)
I1^ii—Cs1—I4^vii	169.26 (2)	I2—I1—Cs1^vi	101.52 (3)
I1^i—Cs1—I4^vi	144.090 (19)	I2—I1—Cs1	74.37 (3)
I1^i—Cs1—I4^vii	106.46 (2)	Cs1—I1—Cs1^vi	100.33 (3)
I1—Cs1—I4^vi	68.28 (3)	Cs1—I1—Cs1^i	96.62 (3)
I1—Cs1—I4	147.55 (3)	Cs1^i—I1—Cs1^vi	157.07 (3)
I1—Cs1—I4^vii	63.18 (2)	I2—I3—Cs1^v	104.39 (4)
I3^v—Cs1—I2	67.09 (3)	I2—I3—Cs1^ix	104.90 (3)
I3^iii—Cs1—I2^i	96.60 (2)	I2—I3—Cs1^x	125.11 (4)
I3^iv—Cs1—I2^i	80.620 (19)	Cs1^v—I3—Cs1^ix	102.23 (3)
I3^iii—Cs1—I2	172.52 (3)	Cs1^v—I3—Cs1^x	100.104 (13)
I3^v—Cs1—I2^i	146.090 (19)	Cs1^x—I3—Cs1^ix	116.78 (4)
I3^iv—Cs1—I2	122.95 (4)	Cs1^xi—I4—Cs1^ii	138.62 (2)
I3^v—Cs1—Cs1^i	106.83 (3)	Cs1—I4—Cs1^ii	95.50 (4)
I3^iv—Cs1—Cs1^i	106.12 (4)	Cs1—I4—Cs1^xi	99.93 (2)
I3^iii—Cs1—Cs1^i	142.04 (2)	I4^viii—I4—Cs1^ii	67.07 (4)
I3^iii—Cs1—I1^i	119.13 (2)	I4^viii—I4—Cs1	112.20 (5)
I3^iv—Cs1—I1^ii	72.69 (2)	I4^viii—I4—Cs1^xi	71.55 (3)

Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, −y+3/2, z+1/2; (iii) x+1, −y+3/2, z+1/2; (iv) −x+1, y+1/2, −z+3/2; (v) −x+1, −y+1, −z+1; (vi) x, −y+3/2, z−1/2; (vii) −x+2, y+1/2, −z+3/2; (viii) −x+2, −y+1, −z+2; (ix) x−1, −y+3/2, z−1/2; (x) −x+1, y−1/2, −z+3/2; (xi) −x+2, y−1/2, −z+3/2.

dicesium octaiodide (CsI4_4p19GPa)

Crystal data

CsI4	F(000) = 1068
Mr = 640.51	Dx = 5.706 Mg m^−3
Monoclinic, P21/c	Synchrotron radiation, λ = 0.41077 Å
a = 9.4705 (13) Å	Cell parameters from 1356 reflections
b = 8.5022 (2) Å	θ = 1.9–21.4°
c = 10.2962 (4) Å	µ = 4.88 mm^−1
β = 115.934 (10)°	T = 296 K
V = 745.56 (12) Å^3	Plate, dark red
Z = 4	0.04 × 0.02 × 0.01 mm

Data collection

Esperanto-CrysAlisPro-abstract goniometer imported esperanto images diffractometer	993 independent reflections
Radiation source: undulator, ID15B, ESRF	952 reflections with I > 2σ(I)
Synchrotron monochromator	Rint = 0.013
Detector resolution: 13.3333 pixels mm^-1	θmax = 21.4°, θmin = 1.9°
phi scan	h = −7→6
Absorption correction: multi-scan CrysAlisPro 1.171.41.93a (Rigaku Oxford Diffraction, 2020) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −12→11
Tmin = 0.865, Tmax = 1.000	l = −15→16
1843 measured reflections

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Primary atom site location: iterative
R[F^2 > 2σ(F^2)] = 0.022	w = 1/[σ^2(Fo^2) + (0.0415P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.061	(Δ/σ)max = 0.001
S = 1.10	Δρmax = 1.13 e Å^−3
993 reflections	Δρmin = −1.33 e Å^−3
46 parameters

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
I2	0.38828 (9)	0.71686 (3)	0.39699 (3)	0.0240 (3)
Cs1	0.77890 (8)	0.88062 (3)	0.69062 (3)	0.0264 (3)
I1	0.56529 (9)	0.91428 (4)	0.30726 (3)	0.0263 (3)
I3	0.17415 (9)	0.49921 (3)	0.45143 (3)	0.0254 (3)
I4	1.05258 (9)	0.65026 (4)	0.99955 (3)	0.0259 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I2	0.0260 (9)	0.02289 (17)	0.02394 (15)	0.00147 (15)	0.0117 (3)	−0.00156 (7)
Cs1	0.0288 (9)	0.02621 (17)	0.02311 (15)	0.00239 (15)	0.0104 (3)	0.00161 (7)
I1	0.0254 (9)	0.03033 (18)	0.02451 (16)	−0.00208 (18)	0.0121 (3)	0.00127 (8)
I3	0.0253 (9)	0.02137 (18)	0.03084 (17)	−0.00040 (17)	0.0136 (3)	0.00227 (8)
I4	0.0253 (9)	0.02277 (18)	0.02885 (16)	0.00385 (16)	0.0112 (3)	0.00183 (8)

Geometric parameters (Å, º)

I2—Cs1^i	3.7126 (5)	Cs1—I3^iii	3.6707 (10)
I2—Cs1	3.8706 (10)	Cs1—I3^iv	3.6557 (4)
I2—I1	2.7993 (8)	Cs1—I3^v	3.6516 (5)
I2—I3	2.9741 (8)	Cs1—I4	3.6688 (7)
Cs1—Cs1^i	5.4128 (14)	Cs1—I4^vi	3.7907 (7)
Cs1—I1	3.5736 (6)	Cs1—I4^vii	3.8880 (9)
Cs1—I1^i	3.7054 (11)	I4—I4^viii	2.7438 (8)
Cs1—I1^ii	3.7344 (8)
Cs1^i—I2—Cs1	91.064 (16)	I3^v—Cs1—I1^i	132.85 (2)
I1—I2—Cs1	62.377 (17)	I3^iii—Cs1—I1^ii	118.302 (13)
I1—I2—Cs1^i	67.691 (19)	I3^iii—Cs1—I1^i	118.878 (15)
I1—I2—I3	172.486 (19)	I3^iv—Cs1—I1^ii	72.850 (13)
I3—I2—Cs1^i	111.46 (3)	I3^v—Cs1—I3^iii	105.982 (19)
I3—I2—Cs1	125.043 (13)	I3^v—Cs1—I3^iv	131.704 (10)
I2^i—Cs1—I2	88.937 (16)	I3^iv—Cs1—I3^iii	63.27 (2)
I2^i—Cs1—Cs1^i	45.640 (11)	I3^v—Cs1—I4^vi	100.105 (16)
I2—Cs1—Cs1^i	43.297 (12)	I3^iv—Cs1—I4^vi	117.444 (14)
I2^i—Cs1—I1^ii	117.62 (2)	I3^iv—Cs1—I4^vii	135.62 (2)
I2^i—Cs1—I4^vi	63.139 (14)	I3^v—Cs1—I4	73.234 (12)
I2^i—Cs1—I4^vii	104.309 (15)	I3^v—Cs1—I4^vii	60.840 (14)
I2—Cs1—I4^vii	101.620 (14)	I3^iv—Cs1—I4	62.926 (13)
I1^i—Cs1—I2^i	44.341 (13)	I3^iii—Cs1—I4^vi	71.613 (17)
I1^ii—Cs1—I2	62.777 (14)	I3^iii—Cs1—I4^vii	72.351 (19)
I1^i—Cs1—I2	68.354 (19)	I4—Cs1—I2^i	140.108 (11)
I1—Cs1—I2^i	71.491 (11)	I4^vi—Cs1—I2	106.773 (13)
I1—Cs1—I2	43.952 (14)	I4—Cs1—I2	123.824 (14)
I1^i—Cs1—Cs1^i	41.034 (11)	I4^vii—Cs1—Cs1^i	108.273 (13)
I1—Cs1—Cs1^i	42.900 (14)	I4^vi—Cs1—Cs1^i	84.056 (14)
I1^ii—Cs1—Cs1^i	89.48 (2)	I4—Cs1—Cs1^i	157.56 (2)
I1—Cs1—I1^ii	106.52 (2)	I4—Cs1—I1^i	122.403 (15)
I1—Cs1—I1^i	83.934 (18)	I4—Cs1—I1^ii	68.865 (17)
I1^i—Cs1—I1^ii	73.285 (15)	I4—Cs1—I3^iii	53.602 (15)
I1—Cs1—I3^iii	133.58 (2)	I4—Cs1—I4^vi	118.25 (2)
I1—Cs1—I3^iv	148.43 (2)	I4^vi—Cs1—I4^vii	41.848 (13)
I1—Cs1—I3^v	74.793 (11)	I4—Cs1—I4^vii	91.61 (2)
I1^i—Cs1—I4^vi	106.775 (14)	I2—I1—Cs1^i	67.97 (2)
I1^i—Cs1—I4^vii	144.847 (12)	I2—I1—Cs1^vii	100.975 (16)
I1—Cs1—I4^vi	62.863 (15)	I2—I1—Cs1	73.671 (16)
I1—Cs1—I4	147.608 (15)	Cs1—I1—Cs1^i	96.067 (18)
I1^ii—Cs1—I4^vii	133.799 (12)	Cs1^i—I1—Cs1^vii	156.861 (18)
I1^ii—Cs1—I4^vi	169.048 (13)	Cs1—I1—Cs1^vii	100.19 (2)
I1—Cs1—I4^vii	68.108 (18)	I2—I3—Cs1^v	105.21 (2)
I3^v—Cs1—I2	67.122 (15)	I2—I3—Cs1^ix	104.488 (18)
I3^iv—Cs1—I2	122.68 (3)	I2—I3—Cs1^x	124.70 (2)
I3^v—Cs1—I2^i	146.262 (12)	Cs1^v—I3—Cs1^ix	102.531 (16)
I3^iv—Cs1—I2^i	80.887 (12)	Cs1^v—I3—Cs1^x	100.220 (8)
I3^iii—Cs1—I2	172.763 (18)	Cs1^x—I3—Cs1^ix	116.73 (2)
I3^iii—Cs1—I2^i	96.388 (16)	Cs1^xi—I4—Cs1^ii	138.152 (13)
I3^v—Cs1—Cs1^i	107.001 (16)	Cs1—I4—Cs1^xi	99.928 (12)
I3^iv—Cs1—Cs1^i	106.11 (2)	Cs1—I4—Cs1^ii	95.75 (2)
I3^iii—Cs1—Cs1^i	141.785 (13)	I4^viii—I4—Cs1^ii	67.18 (2)
I3^iv—Cs1—I1^i	65.397 (18)	I4^viii—I4—Cs1^xi	70.97 (2)
I3^v—Cs1—I1^ii	73.323 (14)	I4^viii—I4—Cs1	112.35 (3)

Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, −y+3/2, z+1/2; (iii) x+1, −y+3/2, z+1/2; (iv) −x+1, y+1/2, −z+3/2; (v) −x+1, −y+1, −z+1; (vi) −x+2, y+1/2, −z+3/2; (vii) x, −y+3/2, z−1/2; (viii) −x+2, −y+1, −z+2; (ix) x−1, −y+3/2, z−1/2; (x) −x+1, y−1/2, −z+3/2; (xi) −x+2, y−1/2, −z+3/2.

dicesium octaiodide (CsI4_4p71GPa)

Crystal data

CsI4	F(000) = 1068
Mr = 640.51	Dx = 5.806 Mg m^−3
Monoclinic, P21/c	Synchrotron radiation, λ = 0.41077 Å
a = 9.4109 (11) Å	Cell parameters from 1318 reflections
b = 8.4696 (1) Å	θ = 1.9–21.5°
c = 10.2258 (3) Å	µ = 4.97 mm^−1
β = 115.972 (9)°	T = 296 K
V = 732.75 (10) Å^3	Plate, dark red
Z = 4	0.04 × 0.02 × 0.01 mm

Data collection

Esperanto-CrysAlisPro-abstract goniometer imported esperanto images diffractometer	951 independent reflections
Radiation source: undulator, ID15B, ESRF	908 reflections with I > 2σ(I)
Synchrotron monochromator	Rint = 0.015
phi scan	θmax = 21.5°, θmin = 1.9°
Absorption correction: multi-scan CrysAlisPro 1.171.41.93a (Rigaku Oxford Diffraction, 2020) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	h = −7→6
Tmin = 0.006, Tmax = 1.000	k = −12→11
1753 measured reflections	l = −15→15

Refinement

Refinement on F^2	46 parameters
Least-squares matrix: full	0 restraints
R[F^2 > 2σ(F^2)] = 0.034	w = 1/[σ^2(Fo^2) + (0.0905P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.132	(Δ/σ)max < 0.001
S = 1.28	Δρmax = 1.30 e Å^−3
951 reflections	Δρmin = −1.25 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
I2	0.38857 (15)	0.71772 (6)	0.39740 (5)	0.0202 (6)
Cs1	0.77912 (15)	0.88112 (6)	0.69044 (5)	0.0236 (5)
I1	0.56555 (17)	0.91539 (7)	0.30624 (6)	0.0231 (6)
I3	0.17409 (16)	0.49815 (6)	0.45113 (6)	0.0224 (6)
I4	1.05279 (16)	0.65089 (6)	0.99980 (6)	0.0234 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I2	0.0164 (17)	0.0225 (3)	0.0233 (3)	0.0012 (3)	0.0102 (5)	−0.00150 (12)
Cs1	0.0230 (16)	0.0253 (3)	0.0223 (3)	0.0026 (3)	0.0096 (5)	0.00150 (12)
I1	0.0185 (18)	0.0295 (4)	0.0237 (3)	−0.0021 (3)	0.0114 (5)	0.00106 (13)
I3	0.0184 (17)	0.0212 (3)	0.0292 (3)	−0.0006 (3)	0.0120 (5)	0.00203 (13)
I4	0.0202 (17)	0.0223 (4)	0.0275 (3)	0.0040 (3)	0.0103 (5)	0.00194 (13)

Geometric parameters (Å, º)

I2—Cs1^i	3.6878 (9)	Cs1—I3^iii	3.6285 (8)
I2—Cs1	3.8415 (15)	Cs1—I3^iv	3.6328 (7)
I2—I1	2.7939 (14)	Cs1—I3^v	3.6454 (16)
I2—I3	2.9674 (14)	Cs1—I4^vi	3.8607 (15)
Cs1—Cs1^i	5.376 (2)	Cs1—I4	3.6478 (11)
Cs1—I1^i	3.6863 (18)	Cs1—I4^vii	3.7687 (12)
Cs1—I1	3.5557 (9)	I4—I4^viii	2.7430 (15)
Cs1—I1^ii	3.7192 (13)
Cs1^i—I2—Cs1	91.10 (3)	I3^iv—Cs1—I1^i	65.26 (3)
I1—I2—Cs1	62.47 (3)	I3^iv—Cs1—I1^ii	72.94 (2)
I1—I2—Cs1^i	67.71 (3)	I3^iii—Cs1—I1^i	132.73 (4)
I1—I2—I3	172.11 (3)	I3^v—Cs1—I1^ii	118.47 (2)
I3—I2—Cs1^i	111.67 (4)	I3^iii—Cs1—I3^iv	131.438 (18)
I3—I2—Cs1	125.26 (2)	I3^iv—Cs1—I3^v	63.35 (4)
I2^i—Cs1—I2	88.90 (3)	I3^iii—Cs1—I3^v	106.08 (3)
I2^i—Cs1—Cs1^i	45.595 (18)	I3^v—Cs1—I4^vi	72.35 (3)
I2—Cs1—Cs1^i	43.301 (19)	I3^iii—Cs1—I4	73.13 (2)
I2^i—Cs1—I1^ii	117.80 (4)	I3^iv—Cs1—I4^vi	135.70 (4)
I2^i—Cs1—I4^vi	104.51 (2)	I3^iii—Cs1—I4^vii	100.32 (3)
I2—Cs1—I4^vi	101.70 (2)	I3^v—Cs1—I4^vii	71.54 (3)
I2^i—Cs1—I4^vii	63.08 (2)	I3^iv—Cs1—I4^vii	117.55 (2)
I1^i—Cs1—I2^i	44.53 (2)	I3^iv—Cs1—I4	62.83 (2)
I1—Cs1—I2^i	71.405 (19)	I3^v—Cs1—I4	53.79 (2)
I1^ii—Cs1—I2	62.57 (2)	I3^iii—Cs1—I4^vi	60.79 (3)
I1^i—Cs1—I2	68.31 (3)	I4—Cs1—I2^i	140.176 (19)
I1—Cs1—I2	44.17 (2)	I4—Cs1—I2	123.70 (2)
I1—Cs1—Cs1^i	43.01 (2)	I4^vii—Cs1—I2	106.87 (2)
I1^i—Cs1—Cs1^i	41.142 (19)	I4—Cs1—Cs1^i	157.41 (4)
I1^ii—Cs1—Cs1^i	89.47 (4)	I4^vi—Cs1—Cs1^i	108.47 (2)
I1—Cs1—I1^ii	106.51 (4)	I4^vii—Cs1—Cs1^i	84.08 (2)
I1—Cs1—I1^i	84.15 (3)	I4—Cs1—I1^ii	68.76 (3)
I1^i—Cs1—I1^ii	73.29 (2)	I4—Cs1—I1^i	122.13 (2)
I1—Cs1—I3^iv	148.50 (4)	I4—Cs1—I4^vii	118.37 (3)
I1—Cs1—I3^v	133.39 (4)	I4—Cs1—I4^vi	91.52 (4)
I1—Cs1—I3^iii	74.935 (18)	I4^vii—Cs1—I4^vi	42.12 (2)
I1^ii—Cs1—I4^vi	133.34 (2)	I2—I1—Cs1^i	67.76 (4)
I1—Cs1—I4	147.63 (3)	I2—I1—Cs1^vi	100.71 (3)
I1^ii—Cs1—I4^vii	168.88 (2)	I2—I1—Cs1	73.35 (3)
I1^i—Cs1—I4^vii	106.93 (2)	Cs1—I1—Cs1^vi	100.01 (4)
I1^i—Cs1—I4^vi	145.26 (2)	Cs1—I1—Cs1^i	95.85 (3)
I1—Cs1—I4^vi	68.10 (3)	Cs1^i—I1—Cs1^vi	156.78 (3)
I1—Cs1—I4^vii	62.75 (3)	I2—I3—Cs1^iii	105.65 (4)
I3^iii—Cs1—I2	67.15 (3)	I2—I3—Cs1^ix	104.31 (3)
I3^v—Cs1—I2^i	96.33 (3)	I2—I3—Cs1^x	124.48 (4)
I3^iv—Cs1—I2^i	81.039 (19)	Cs1^iii—I3—Cs1^ix	102.69 (3)
I3^v—Cs1—I2	172.89 (3)	Cs1^iii—I3—Cs1^x	100.295 (13)
I3^iii—Cs1—I2^i	146.33 (2)	Cs1^x—I3—Cs1^ix	116.65 (4)
I3^iv—Cs1—I2	122.49 (4)	Cs1^xi—I4—Cs1^ii	137.88 (2)
I3^iii—Cs1—Cs1^i	107.06 (3)	Cs1—I4—Cs1^ii	95.83 (4)
I3^iv—Cs1—Cs1^i	106.08 (4)	Cs1—I4—Cs1^xi	99.96 (2)
I3^v—Cs1—Cs1^i	141.69 (2)	I4^viii—I4—Cs1^ii	67.15 (4)
I3^iii—Cs1—I1^ii	72.91 (2)	I4^viii—I4—Cs1	112.38 (6)
I3^v—Cs1—I1^i	118.79 (2)	I4^viii—I4—Cs1^xi	70.73 (3)

Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, −y+3/2, z+1/2; (iii) −x+1, −y+1, −z+1; (iv) −x+1, y+1/2, −z+3/2; (v) x+1, −y+3/2, z+1/2; (vi) x, −y+3/2, z−1/2; (vii) −x+2, y+1/2, −z+3/2; (viii) −x+2, −y+1, −z+2; (ix) x−1, −y+3/2, z−1/2; (x) −x+1, y−1/2, −z+3/2; (xi) −x+2, y−1/2, −z+3/2.

dicesium octaiodide (CsI4_5p42GPa)

Crystal data

CsI4	F(000) = 1068
Mr = 640.51	Dx = 5.902 Mg m^−3
Monoclinic, P21/c	Synchrotron radiation, λ = 0.41077 Å
a = 9.3544 (14) Å	Cell parameters from 1303 reflections
b = 8.4389 (2) Å	θ = 1.9–21.6°
c = 10.1587 (4) Å	µ = 5.05 mm^−1
β = 115.998 (11)°	T = 296 K
V = 720.79 (13) Å^3	Plate, dark red
Z = 4	0.04 × 0.02 × 0.01 mm

Data collection

Esperanto-CrysAlisPro-abstract goniometer imported esperanto images diffractometer	935 independent reflections
Radiation source: undulator, ID15B, ESRF	896 reflections with I > 2σ(I)
Synchrotron monochromator	Rint = 0.013
Detector resolution: 13.3333 pixels mm^-1	θmax = 21.6°, θmin = 2.6°
phi scan	h = −6→7
Absorption correction: multi-scan CrysAlisPro 1.171.41.93a (Rigaku Oxford Diffraction, 2020) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −12→11
Tmin = 0.551, Tmax = 1.000	l = −15→15
1710 measured reflections

Refinement

Refinement on F^2	46 parameters
Least-squares matrix: full	0 restraints
R[F^2 > 2σ(F^2)] = 0.022	w = 1/[σ^2(Fo^2) + (0.052P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.068	(Δ/σ)max = 0.001
S = 1.05	Δρmax = 0.68 e Å^−3
935 reflections	Δρmin = −0.74 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
I2	0.38913 (9)	0.71854 (3)	0.39784 (3)	0.0242 (3)
Cs1	0.77903 (9)	0.88148 (3)	0.69026 (3)	0.0265 (3)
I1	0.56621 (10)	0.91642 (4)	0.30535 (3)	0.0265 (3)
I3	0.17419 (10)	0.49716 (3)	0.45078 (4)	0.0257 (3)
I4	1.05287 (9)	0.65138 (4)	1.00013 (3)	0.0258 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I2	0.0283 (9)	0.02118 (18)	0.02252 (17)	0.00130 (16)	0.0107 (3)	−0.00149 (8)
Cs1	0.0320 (9)	0.02404 (18)	0.02125 (16)	0.00198 (15)	0.0096 (3)	0.00131 (7)
I1	0.0289 (10)	0.0283 (2)	0.02244 (18)	−0.00225 (19)	0.0112 (3)	0.00084 (8)
I3	0.0286 (10)	0.01998 (19)	0.02803 (18)	−0.00023 (18)	0.0120 (3)	0.00202 (8)
I4	0.0278 (9)	0.02089 (19)	0.02663 (18)	0.00354 (17)	0.0101 (3)	0.00181 (8)

Geometric parameters (Å, º)

I2—Cs1^i	3.6653 (5)	Cs1—I3^iii	3.6062 (5)
I2—Cs1	3.8104 (10)	Cs1—I3^iv	3.6115 (4)
I2—I1	2.7891 (8)	Cs1—I3^v	3.6250 (11)
I2—I3	2.9614 (9)	Cs1—I4^vi	3.8350 (10)
Cs1—Cs1^i	5.3390 (15)	Cs1—I4	3.6294 (8)
Cs1—I1^i	3.6696 (11)	Cs1—I4^vii	3.7507 (8)
Cs1—I1	3.5377 (6)	I4—I4^viii	2.7393 (9)
Cs1—I1^ii	3.7001 (8)
Cs1^i—I2—Cs1	91.130 (18)	I3^iv—Cs1—I1^i	65.158 (19)
I1—I2—Cs1^i	67.73 (2)	I3^iii—Cs1—I1^ii	72.503 (15)
I1—I2—Cs1	62.596 (18)	I3^iv—Cs1—I1^ii	73.049 (14)
I1—I2—I3	171.732 (18)	I3^v—Cs1—I1^ii	118.617 (14)
I3—I2—Cs1	125.457 (14)	I3^iii—Cs1—I3^v	106.14 (2)
I3—I2—Cs1^i	111.86 (3)	I3^iii—Cs1—I3^iv	131.194 (11)
I2^i—Cs1—I2	88.870 (17)	I3^iv—Cs1—I3^v	63.45 (2)
I2—Cs1—Cs1^i	43.345 (13)	I3^iv—Cs1—I4^vi	135.73 (3)
I2^i—Cs1—Cs1^i	45.525 (11)	I3^iii—Cs1—I4^vii	100.479 (17)
I2^i—Cs1—I1^ii	118.04 (2)	I3^iv—Cs1—I4	62.729 (14)
I2^i—Cs1—I1^i	44.699 (13)	I3^v—Cs1—I4^vi	72.28 (2)
I2—Cs1—I4^vi	101.753 (16)	I3^v—Cs1—I4	53.967 (16)
I2^i—Cs1—I4^vi	104.687 (15)	I3^iv—Cs1—I4^vii	117.638 (15)
I2^i—Cs1—I4^vii	63.058 (15)	I3^v—Cs1—I4^vii	71.403 (18)
I1^ii—Cs1—I2	62.449 (15)	I3^iii—Cs1—I4	73.029 (13)
I1—Cs1—I2	44.421 (15)	I3^iii—Cs1—I4^vi	60.767 (15)
I1—Cs1—I2^i	71.339 (12)	I4—Cs1—I2^i	140.235 (11)
I1^i—Cs1—I2	68.31 (2)	I4—Cs1—I2	123.614 (16)
I1^ii—Cs1—Cs1^i	89.58 (2)	I4^vii—Cs1—I2	106.948 (14)
I1—Cs1—Cs1^i	43.164 (15)	I4—Cs1—Cs1^i	157.34 (2)
I1^i—Cs1—Cs1^i	41.260 (12)	I4^vi—Cs1—Cs1^i	108.628 (15)
I1—Cs1—I1^ii	106.61 (2)	I4^vii—Cs1—Cs1^i	84.087 (15)
I1—Cs1—I1^i	84.424 (19)	I4—Cs1—I1^ii	68.616 (18)
I1^i—Cs1—I1^ii	73.362 (16)	I4—Cs1—I1^i	121.900 (16)
I1—Cs1—I3^iii	75.060 (11)	I4—Cs1—I4^vii	118.43 (2)
I1—Cs1—I3^v	133.09 (2)	I4—Cs1—I4^vi	91.42 (2)
I1—Cs1—I3^iv	148.64 (2)	I4^vii—Cs1—I4^vi	42.320 (14)
I1^ii—Cs1—I4^vii	168.755 (14)	I2—I1—Cs1^i	67.57 (2)
I1^i—Cs1—I4^vii	107.106 (15)	I2—I1—Cs1^vi	100.424 (17)
I1^i—Cs1—I4^vi	145.630 (12)	I2—I1—Cs1	72.983 (17)
I1—Cs1—I4	147.621 (16)	Cs1—I1—Cs1^vi	99.94 (2)
I1^ii—Cs1—I4^vi	132.901 (13)	Cs1—I1—Cs1^i	95.58 (2)
I1—Cs1—I4^vi	68.029 (19)	Cs1^i—I1—Cs1^vi	156.618 (19)
I1—Cs1—I4^vii	62.576 (16)	I2—I3—Cs1^iii	106.05 (2)
I3^iii—Cs1—I2	67.163 (17)	I2—I3—Cs1^ix	104.206 (19)
I3^iii—Cs1—I2^i	146.389 (13)	I2—I3—Cs1^x	124.23 (2)
I3^v—Cs1—I2^i	96.271 (17)	Cs1^iii—I3—Cs1^ix	102.871 (18)
I3^v—Cs1—I2	172.93 (2)	Cs1^iii—I3—Cs1^x	100.344 (8)
I3^iv—Cs1—I2^i	81.181 (12)	Cs1^x—I3—Cs1^ix	116.55 (2)
I3^iv—Cs1—I2	122.39 (3)	Cs1^xi—I4—Cs1^ii	137.681 (14)
I3^iii—Cs1—Cs1^i	107.143 (17)	Cs1—I4—Cs1^ii	95.86 (3)
I3^iv—Cs1—Cs1^i	106.08 (2)	Cs1—I4—Cs1^xi	100.002 (13)
I3^v—Cs1—Cs1^i	141.560 (14)	I4^viii—I4—Cs1^ii	67.20 (3)
I3^v—Cs1—I1^i	118.751 (16)	I4^viii—I4—Cs1	112.39 (3)
I3^iii—Cs1—I1^i	132.64 (3)	I4^viii—I4—Cs1^xi	70.48 (2)

Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, −y+3/2, z+1/2; (iii) −x+1, −y+1, −z+1; (iv) −x+1, y+1/2, −z+3/2; (v) x+1, −y+3/2, z+1/2; (vi) x, −y+3/2, z−1/2; (vii) −x+2, y+1/2, −z+3/2; (viii) −x+2, −y+1, −z+2; (ix) x−1, −y+3/2, z−1/2; (x) −x+1, y−1/2, −z+3/2; (xi) −x+2, y−1/2, −z+3/2.

dicesium octaiodide (CsI4_5p91GPa)

Crystal data

CsI4	F(000) = 1068
Mr = 640.51	Dx = 6.006 Mg m^−3
Monoclinic, P21/c	Synchrotron radiation, λ = 0.41077 Å
a = 9.2978 (12) Å	Cell parameters from 1294 reflections
b = 8.4056 (2) Å	θ = 1.9–21.1°
c = 10.0857 (4) Å	µ = 5.14 mm^−1
β = 116.015 (9)°	T = 296 K
V = 708.37 (11) Å^3	Plate, dark red
Z = 4	0.04 × 0.02 × 0.01 mm

Data collection

Esperanto-CrysAlisPro-abstract goniometer imported esperanto images diffractometer	860 reflections with I > 2σ(I)
Radiation source: undulator, ID15B, ESRF	Rint = 0.025
Synchrotron monochromator	θmax = 21.3°, θmin = 1.9°
Detector resolution: 13.3333 pixels mm^-1	h = −7→5
phi scan	k = −12→11
1604 measured reflections	l = −15→15
899 independent reflections

Refinement

Refinement on F^2	46 parameters
Least-squares matrix: full	0 restraints
R[F^2 > 2σ(F^2)] = 0.019	w = 1/[σ^2(Fo^2) + (0.0316P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.049	(Δ/σ)max = 0.001
S = 1.01	Δρmax = 0.58 e Å^−3
899 reflections	Δρmin = −0.52 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
I2	0.38972 (9)	0.71948 (3)	0.39838 (3)	0.0216 (3)
Cs1	0.77902 (8)	0.88193 (3)	0.69010 (3)	0.0229 (2)
I1	0.56683 (9)	0.91747 (4)	0.30441 (3)	0.0236 (3)
I3	0.17419 (9)	0.49604 (3)	0.45035 (3)	0.0226 (3)
I4	1.05296 (8)	0.65198 (3)	1.00041 (3)	0.0230 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I2	0.0229 (8)	0.02000 (15)	0.02196 (14)	0.00121 (15)	0.0098 (2)	−0.00136 (7)
Cs1	0.0242 (7)	0.02259 (15)	0.02038 (13)	0.00160 (14)	0.0083 (2)	0.00115 (7)
I1	0.0226 (9)	0.02693 (16)	0.02159 (15)	−0.00242 (17)	0.0100 (3)	0.00070 (8)
I3	0.0222 (8)	0.01899 (15)	0.02699 (15)	−0.00044 (16)	0.0111 (3)	0.00192 (7)
I4	0.0223 (8)	0.01960 (16)	0.02585 (15)	0.00303 (16)	0.0094 (3)	0.00168 (7)

Geometric parameters (Å, º)

I2—Cs1^i	3.6408 (5)	Cs1—I3^iii	3.5819 (4)
I2—Cs1	3.7789 (9)	Cs1—I3^iv	3.5883 (4)
I2—I1	2.7836 (8)	Cs1—I3^v	3.6030 (10)
I2—I3	2.9562 (8)	Cs1—I4^vi	3.8083 (9)
Cs1—Cs1^i	5.3021 (13)	Cs1—I4	3.6092 (7)
Cs1—I1^i	3.6527 (10)	Cs1—I4^vii	3.7307 (7)
Cs1—I1	3.5186 (5)	I4—I4^viii	2.7369 (8)
Cs1—I1^ii	3.6811 (7)
Cs1^i—I2—Cs1	91.200 (16)	I3^iv—Cs1—I1^i	65.078 (16)
I1—I2—Cs1^i	67.792 (18)	I3^iii—Cs1—I1^ii	72.074 (13)
I1—I2—Cs1	62.703 (17)	I3^iv—Cs1—I1^ii	73.158 (12)
I1—I2—I3	171.278 (17)	I3^v—Cs1—I1^ii	118.806 (13)
I3—I2—Cs1	125.720 (13)	I3^iii—Cs1—I3^v	106.181 (18)
I3—I2—Cs1^i	112.05 (3)	I3^iii—Cs1—I3^iv	130.906 (9)
I2^i—Cs1—I2	88.801 (15)	I3^iv—Cs1—I3^v	63.56 (2)
I2—Cs1—Cs1^i	43.355 (11)	I3^iv—Cs1—I4^vi	135.75 (2)
I2^i—Cs1—Cs1^i	45.445 (11)	I3^iii—Cs1—I4^vii	100.666 (15)
I2^i—Cs1—I1^ii	118.25 (2)	I3^iv—Cs1—I4	62.622 (12)
I2^i—Cs1—I1^i	44.873 (13)	I3^v—Cs1—I4^vi	72.196 (18)
I2—Cs1—I4^vi	101.837 (14)	I3^v—Cs1—I4	54.156 (14)
I2^i—Cs1—I4^vi	104.893 (14)	I3^iv—Cs1—I4^vii	117.731 (13)
I2^i—Cs1—I4^vii	63.039 (14)	I3^v—Cs1—I4^vii	71.240 (16)
I1^ii—Cs1—I2	62.284 (13)	I3^iii—Cs1—I4	72.901 (12)
I1—Cs1—I2	44.669 (14)	I3^iii—Cs1—I4^vi	60.723 (13)
I1—Cs1—I2^i	71.247 (11)	I4—Cs1—I2^i	140.330 (10)
I1^i—Cs1—I2	68.262 (18)	I4—Cs1—I2	123.524 (14)
I1^ii—Cs1—Cs1^i	89.63 (2)	I4^vii—Cs1—I2	107.058 (12)
I1—Cs1—Cs1^i	43.311 (13)	I4—Cs1—Cs1^i	157.25 (2)
I1^i—Cs1—Cs1^i	41.358 (11)	I4^vi—Cs1—Cs1^i	108.825 (12)
I1—Cs1—I1^ii	106.66 (2)	I4^vii—Cs1—Cs1^i	84.131 (14)
I1—Cs1—I1^i	84.669 (17)	I4—Cs1—I1^ii	68.506 (16)
I1^i—Cs1—I1^ii	73.413 (14)	I4—Cs1—I1^i	121.682 (15)
I1—Cs1—I3^iii	75.202 (10)	I4—Cs1—I4^vii	118.48 (2)
I1—Cs1—I3^v	132.79 (2)	I4—Cs1—I4^vi	91.29 (2)
I1—Cs1—I3^iv	148.78 (2)	I4^vii—Cs1—I4^vi	42.557 (12)
I1^ii—Cs1—I4^vii	168.612 (12)	I2—I1—Cs1^i	67.34 (2)
I1^i—Cs1—I4^vii	107.291 (13)	I2—I1—Cs1^vi	100.152 (15)
I1^i—Cs1—I4^vi	146.032 (11)	I2—I1—Cs1	72.628 (15)
I1—Cs1—I4	147.606 (14)	Cs1—I1—Cs1^vi	99.820 (19)
I1^ii—Cs1—I4^vi	132.423 (12)	Cs1—I1—Cs1^i	95.331 (18)
I1—Cs1—I4^vi	67.992 (17)	Cs1^i—I1—Cs1^vi	156.442 (17)
I1—Cs1—I4^vii	62.443 (14)	I2—I3—Cs1^iii	106.50 (2)
I3^iii—Cs1—I2	67.208 (15)	I2—I3—Cs1^ix	104.120 (17)
I3^iii—Cs1—I2^i	146.444 (12)	I2—I3—Cs1^x	123.91 (2)
I3^v—Cs1—I2^i	96.240 (15)	Cs1^iii—I3—Cs1^ix	103.082 (16)
I3^v—Cs1—I2	172.993 (18)	Cs1^iii—I3—Cs1^x	100.407 (8)
I3^iv—Cs1—I2^i	81.368 (11)	Cs1^x—I3—Cs1^ix	116.44 (2)
I3^iv—Cs1—I2	122.25 (2)	Cs1^xi—I4—Cs1^ii	137.443 (12)
I3^iii—Cs1—Cs1^i	107.225 (15)	Cs1—I4—Cs1^ii	95.89 (2)
I3^iv—Cs1—Cs1^i	106.10 (2)	Cs1—I4—Cs1^xi	100.073 (12)
I3^v—Cs1—Cs1^i	141.449 (12)	I4^viii—I4—Cs1^ii	67.21 (2)
I3^v—Cs1—I1^i	118.735 (15)	I4^viii—I4—Cs1	112.41 (3)
I3^iii—Cs1—I1^i	132.52 (2)	I4^viii—I4—Cs1^xi	70.235 (19)

Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, −y+3/2, z+1/2; (iii) −x+1, −y+1, −z+1; (iv) −x+1, y+1/2, −z+3/2; (v) x+1, −y+3/2, z+1/2; (vi) x, −y+3/2, z−1/2; (vii) −x+2, y+1/2, −z+3/2; (viii) −x+2, −y+1, −z+2; (ix) x−1, −y+3/2, z−1/2; (x) −x+1, y−1/2, −z+3/2; (xi) −x+2, y−1/2, −z+3/2.