[epsilon]-RbCuCl₃, a new polymorph of rubidium copper trichloride: synthesis, structure and structural complexity

A novel polymorph of RbCuCl₃ (rubidium copper trichloride), denoted [epsilon]-RbCuCl₃, has been prepared by chemical vapour transport (CVT) from a mixture of CuO, CuCl₂, SeO₂ and RbCl. The new polymorph crystallizes in the ortho­rhom­bic space group C222₁. The crystal structure is based on an octa­hedral framework of the 4H perovskite type. The Rb⁺ and Cl⁻ ions form a four-layer closest-packing array with an ABCB sequence. The Cu²⁺ cations reside in octa­hedral cavities with a typical [4 + 2]-Jahn–Teller-distorted coordination, forming four short and two long Cu—Cl bonds. [epsilon]-RbCuCl₃ is the most structurally complex and most dense among all currently known RbCuCl₃ polymorphs, which allows us to suggest that it is a high-pressure phase, which is unstable under ambient conditions.

Computing details

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: OLEX2 (Dolomanov et al., 2009) and DIAMOND (Brandenburg & Putz, 1999); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

Rubidium copper trichloride

Crystal data

RbCuCl3	Dx = 3.440 Mg m^−3
Mr = 255.36	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, C2221	Cell parameters from 1041 reflections
a = 7.053 (3) Å	θ = 3.4–33.6°
b = 11.864 (5) Å	µ = 15.67 mm^−1
c = 11.785 (6) Å	T = 100 K
V = 986.1 (8) Å^3	Prism, red
Z = 8	0.08 × 0.05 × 0.03 mm
F(000) = 936

Data collection

Bruker APEXII CCD diffractometer	1042 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.044
φ and ω scans	θmax = 28.0°, θmin = 3.4°
Absorption correction: multi-scan	h = −9→9
	k = −15→15
4745 measured reflections	l = −8→15
1184 independent reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.012P)^2] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.028	(Δ/σ)max < 0.001
wR(F^2) = 0.044	Δρmax = 0.60 e Å^−3
S = 1.02	Δρmin = −0.70 e Å^−3
1184 reflections	Absolute structure: Refined as an inversion twin
49 parameters	Absolute structure parameter: 0.495 (19)
0 restraints

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.

Refinement. Refined as a 2-component inversion twin.

Data were collected using Bruker Kappa Duo diffractometer equipped with an APEX II CCD detector operated with monochromated MoKα radiation at 50 kV and 40 mA. Diffraction data were collected at 100 K with the frame width of 0.5^o in ω and φ, and exposure of 60 s spent per each frame. Data were integrated and corrected for background, Lorentz, and polarization effects using an empirical spherical model by means of the Bruker programs APEX2 and XPREP. Absorption correction was applied using SADABS program. The unit-cell parameters were refined by the least-squares techniques. The structure was solved by direct methods and refined using the SHELX program (Sheldrick, 2008) incorporated in the OLEX2 program package (Dolomanov et al., 2009).

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

	x	y	z	Uiso*/Ueq
Rb1	0.0000	0.32138 (6)	0.2500	0.0105 (2)
Rb2	0.01172 (15)	0.0000	0.0000	0.0111 (2)
Cu1	0.51064 (15)	0.15615 (6)	0.11987 (7)	0.00720 (18)
Cl1	0.5000	0.30598 (14)	0.2500	0.0089 (4)
Cl2	0.2142 (2)	0.26279 (13)	0.51375 (15)	0.0108 (4)
Cl3	0.2555 (2)	0.07319 (11)	0.27800 (13)	0.0089 (3)
Cl4	0.0034 (4)	0.5000	0.0000	0.0123 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Rb1	0.0105 (4)	0.0090 (4)	0.0119 (5)	0.000	−0.0003 (6)	0.000
Rb2	0.0094 (4)	0.0099 (4)	0.0141 (5)	0.000	0.000	−0.0020 (4)
Cu1	0.0086 (4)	0.0061 (3)	0.0069 (4)	0.0010 (4)	−0.0018 (4)	−0.0008 (3)
Cl1	0.0115 (10)	0.0067 (8)	0.0085 (11)	0.000	0.0000 (14)	0.000
Cl2	0.0111 (8)	0.0109 (8)	0.0105 (9)	0.0022 (7)	0.0043 (7)	−0.0016 (7)
Cl3	0.0083 (6)	0.0090 (6)	0.0094 (9)	−0.0018 (6)	0.0001 (8)	−0.0011 (6)
Cl4	0.0139 (9)	0.0105 (9)	0.0125 (12)	0.000	0.000	−0.0061 (9)

Geometric parameters (Å, º)

Rb1—Cl1	3.5313 (15)	Cu1—Rb1^xiii	4.2554 (17)
Rb1—Cl1^i	3.5313 (15)	Cu1—Rb1^xii	4.2581 (19)
Rb1—Cl2^ii	3.579 (2)	Cu1—Rb2^xiii	4.2330 (19)
Rb1—Cl2^iii	3.525 (2)	Cu1—Cl1	2.3489 (16)
Rb1—Cl2^iv	3.579 (2)	Cu1—Cl2^iv	2.2372 (19)
Rb1—Cl2	3.525 (2)	Cu1—Cl3^xiv	2.2667 (19)
Rb1—Cl3^v	3.4651 (19)	Cu1—Cl4^xii	2.3303 (11)
Rb1—Cl3^vi	3.4651 (19)	Cl1—Rb1^xiii	3.5313 (16)
Rb1—Cl3	3.4680 (19)	Cl1—Rb2^xv	3.7397 (17)
Rb1—Cl3^iii	3.4680 (19)	Cl1—Rb2^xvi	3.7397 (17)
Rb1—Cl4	3.6292 (14)	Cl1—Cu1^xiv	2.3489 (16)
Rb1—Cl4^vii	3.6292 (14)	Cl2—Rb1^xv	3.579 (2)
Rb2—Cl1^viii	3.7397 (17)	Cl2—Rb2^xv	3.418 (2)
Rb2—Cl1^iv	3.7397 (17)	Cl2—Rb2^xvii	3.505 (2)
Rb2—Cl2^iv	3.418 (2)	Cl2—Cu1^xv	2.2372 (19)
Rb2—Cl2^ix	3.418 (2)	Cl3—Rb1^xii	3.4651 (19)
Rb2—Cl2^iii	3.505 (2)	Cl3—Rb2^xvii	3.339 (2)
Rb2—Cl2^x	3.505 (2)	Cl3—Cu1^xiv	2.2666 (19)
Rb2—Cl3^iii	3.339 (2)	Cl4—Rb1^xviii	3.6292 (14)
Rb2—Cl3^x	3.339 (2)	Cl4—Rb2^v	3.468 (4)
Rb2—Cl3^xi	3.800 (2)	Cl4—Rb2^xvi	3.585 (4)
Rb2—Cl3	3.800 (2)	Cl4—Cu1^xix	2.3303 (11)
Rb2—Cl4^xii	3.468 (4)	Cl4—Cu1^v	2.3303 (11)
Rb2—Cl4^viii	3.585 (4)
Cl1—Rb1—Cl1^i	174.07 (6)	Cl3^x—Rb2—Cl2^ix	93.90 (4)
Cl1^i—Rb1—Cl2^iv	123.22 (3)	Cl3^x—Rb2—Cl2^iv	124.78 (4)
Cl1—Rb1—Cl2^ii	123.22 (3)	Cl3^iii—Rb2—Cl2^x	86.47 (4)
Cl1—Rb1—Cl2^iv	54.77 (3)	Cl3^iii—Rb2—Cl2^ix	124.78 (4)
Cl1^i—Rb1—Cl2^ii	54.77 (3)	Cl3^x—Rb2—Cl2^iii	86.47 (4)
Cl1^i—Rb1—Cl4^vii	91.35 (5)	Cl3^x—Rb2—Cl2^x	63.15 (4)
Cl1^i—Rb1—Cl4	92.11 (5)	Cl3^iii—Rb2—Cl3^xi	171.95 (4)
Cl1—Rb1—Cl4	91.35 (5)	Cl3^xi—Rb2—Cl3	126.20 (6)
Cl1—Rb1—Cl4^vii	92.11 (5)	Cl3^x—Rb2—Cl3^iii	111.27 (7)
Cl2—Rb1—Cl1	64.01 (3)	Cl3^x—Rb2—Cl3	171.95 (4)
Cl2^iii—Rb1—Cl1	114.70 (3)	Cl3^iii—Rb2—Cl3	61.35 (5)
Cl2^iii—Rb1—Cl1^i	64.01 (3)	Cl3^x—Rb2—Cl3^xi	61.35 (5)
Cl2—Rb1—Cl1^i	114.70 (3)	Cl3^iii—Rb2—Cl4^viii	55.64 (3)
Cl2^iv—Rb1—Cl2^ii	147.60 (6)	Cl3^x—Rb2—Cl4^xii	124.36 (3)
Cl2^iii—Rb1—Cl2	157.25 (6)	Cl3^iii—Rb2—Cl4^xii	124.36 (3)
Cl2—Rb1—Cl2^ii	60.03 (3)	Cl3^x—Rb2—Cl4^viii	55.64 (3)
Cl2^iii—Rb1—Cl2^iv	60.03 (3)	Cl4^xii—Rb2—Cl1^viii	91.267 (16)
Cl2—Rb1—Cl2^iv	112.92 (3)	Cl4^viii—Rb2—Cl1^viii	88.733 (16)
Cl2^iii—Rb1—Cl2^ii	112.92 (3)	Cl4^xii—Rb2—Cl1^iv	91.267 (16)
Cl2^iv—Rb1—Cl4	61.82 (5)	Cl4^viii—Rb2—Cl1^iv	88.733 (16)
Cl2^iii—Rb1—Cl4	53.29 (4)	Cl4^xii—Rb2—Cl2^x	117.04 (3)
Cl2^ii—Rb1—Cl4^vii	61.82 (5)	Cl4^xii—Rb2—Cl2^iii	117.04 (3)
Cl2^ii—Rb1—Cl4	142.95 (6)	Cl4^xii—Rb2—Cl3	63.10 (3)
Cl2^iv—Rb1—Cl4^vii	142.95 (6)	Cl4^viii—Rb2—Cl3	116.90 (3)
Cl2—Rb1—Cl4	145.90 (5)	Cl4^xii—Rb2—Cl3^xi	63.10 (3)
Cl2^iii—Rb1—Cl4^vii	145.90 (5)	Cl4^viii—Rb2—Cl3^xi	116.90 (3)
Cl2—Rb1—Cl4^vii	53.29 (4)	Cl4^xii—Rb2—Cl4^viii	180.0
Cl3^vi—Rb1—Cl1^i	122.79 (4)	Rb1^xiii—Cu1—Rb1^xii	108.31 (3)
Cl3^v—Rb1—Cl1	122.79 (4)	Rb2^xiii—Cu1—Rb1^xii	74.14 (2)
Cl3^iii—Rb1—Cl1	118.36 (4)	Rb2—Cu1—Rb1^xii	72.33 (2)
Cl3—Rb1—Cl1^i	118.36 (4)	Rb2^xiii—Cu1—Rb1^xiii	69.19 (4)
Cl3^vi—Rb1—Cl1	63.10 (4)	Rb2—Cu1—Rb1^xiii	177.68 (3)
Cl3^iii—Rb1—Cl1^i	55.74 (4)	Rb2—Cu1—Rb2^xiii	113.10 (3)
Cl3—Rb1—Cl1	55.74 (4)	Cl1—Cu1—Rb1^xii	118.05 (5)
Cl3^v—Rb1—Cl1^i	63.10 (4)	Cl1—Cu1—Rb1^xiii	56.08 (3)
Cl3^iii—Rb1—Cl2^iii	61.70 (4)	Cl1—Cu1—Rb2^xiii	125.15 (4)
Cl3^v—Rb1—Cl2^iii	92.33 (4)	Cl1—Cu1—Rb2	121.61 (4)
Cl3^iii—Rb1—Cl2^ii	62.90 (4)	Cl2^iv—Cu1—Rb1^xii	126.15 (6)
Cl3^vi—Rb1—Cl2^iii	107.42 (4)	Cl2^iv—Cu1—Rb1^xiii	125.34 (6)
Cl3^vi—Rb1—Cl2^ii	126.50 (4)	Cl2^iv—Cu1—Rb2^xiii	126.41 (6)
Cl3^vi—Rb1—Cl2^iv	83.47 (4)	Cl2^iv—Cu1—Rb2	53.87 (5)
Cl3^vi—Rb1—Cl2	92.33 (4)	Cl2^iv—Cu1—Cl1	90.97 (6)
Cl3^v—Rb1—Cl2^iv	126.50 (4)	Cl2^iv—Cu1—Cl3^xiv	178.05 (8)
Cl3—Rb1—Cl2^iii	98.00 (4)	Cl2^iv—Cu1—Cl4^xii	89.27 (8)
Cl3—Rb1—Cl2^iv	62.90 (4)	Cl3^xiv—Cu1—Rb1^xii	54.31 (4)
Cl3^v—Rb1—Cl2^ii	83.47 (4)	Cl3^xiv—Cu1—Rb1^xiii	54.44 (5)
Cl3^iii—Rb1—Cl2^iv	88.95 (4)	Cl3^xiv—Cu1—Rb2^xiii	51.66 (5)
Cl3—Rb1—Cl2	61.70 (4)	Cl3^xiv—Cu1—Rb2	126.43 (5)
Cl3^iii—Rb1—Cl2	98.00 (4)	Cl3^xiv—Cu1—Cl1	90.30 (6)
Cl3^v—Rb1—Cl2	107.42 (4)	Cl3^xiv—Cu1—Cl4^xii	89.58 (7)
Cl3—Rb1—Cl2^ii	88.95 (4)	Cl4^xii—Cu1—Rb1^xii	58.43 (4)
Cl3^vi—Rb1—Cl3^iii	168.98 (5)	Cl4^xii—Cu1—Rb1^xiii	127.05 (8)
Cl3^vi—Rb1—Cl3	118.85 (3)	Cl4^xii—Cu1—Rb2	55.24 (7)
Cl3^vi—Rb1—Cl3^v	60.89 (6)	Cl4^xii—Cu1—Rb2^xiii	57.87 (8)
Cl3^v—Rb1—Cl3^iii	118.85 (3)	Cl4^xii—Cu1—Cl1	175.37 (6)
Cl3—Rb1—Cl3^iii	63.78 (6)	Rb1—Cl1—Rb1^xiii	174.07 (6)
Cl3^v—Rb1—Cl3	168.98 (5)	Rb1^xiii—Cl1—Rb2^xv	89.44 (2)
Cl3^v—Rb1—Cl4^vii	54.27 (4)	Rb1—Cl1—Rb2^xv	86.91 (3)
Cl3^vi—Rb1—Cl4	54.27 (4)	Rb1—Cl1—Rb2^xvi	89.44 (2)
Cl3—Rb1—Cl4^vii	114.96 (4)	Rb1^xiii—Cl1—Rb2^xvi	86.91 (3)
Cl3^iii—Rb1—Cl4	114.96 (4)	Rb2^xv—Cl1—Rb2^xvi	104.02 (5)
Cl3^iii—Rb1—Cl4^vii	124.72 (4)	Cu1^xiv—Cl1—Rb1^xiii	94.08 (3)
Cl3^v—Rb1—Cl4	64.99 (4)	Cu1—Cl1—Rb1	94.08 (3)
Cl3—Rb1—Cl4	124.72 (4)	Cu1^xiv—Cl1—Rb1	90.42 (3)
Cl3^vi—Rb1—Cl4^vii	64.99 (4)	Cu1—Cl1—Rb1^xiii	90.42 (3)
Cl4^vii—Rb1—Cl4	108.55 (4)	Cu1—Cl1—Rb2^xvi	87.18 (4)
Cl1^iv—Rb2—Cl1^viii	177.47 (3)	Cu1—Cl1—Rb2^xv	168.77 (5)
Cl1^iv—Rb2—Cl3	123.26 (4)	Cu1^xiv—Cl1—Rb2^xvi	168.77 (5)
Cl1^viii—Rb2—Cl3^xi	123.26 (4)	Cu1^xiv—Cl1—Rb2^xv	87.18 (4)
Cl1^iv—Rb2—Cl3^xi	58.10 (4)	Cu1^xiv—Cl1—Cu1	81.64 (7)
Cl1^viii—Rb2—Cl3	58.10 (4)	Rb1—Cl2—Rb1^xv	169.18 (5)
Cl2^x—Rb2—Cl1^viii	53.56 (4)	Rb2^xv—Cl2—Rb1	92.19 (5)
Cl2^x—Rb2—Cl1^iv	125.02 (4)	Rb2^xvii—Cl2—Rb1^xv	92.51 (5)
Cl2^ix—Rb2—Cl1^viii	62.81 (4)	Rb2^xvii—Cl2—Rb1	86.55 (4)
Cl2^iii—Rb2—Cl1^viii	125.02 (4)	Rb2^xv—Cl2—Rb1^xv	87.03 (4)
Cl2^iii—Rb2—Cl1^iv	53.56 (4)	Rb2^xv—Cl2—Rb2^xvii	170.86 (6)
Cl2^iv—Rb2—Cl1^iv	62.81 (4)	Cu1^xv—Cl2—Rb1	95.98 (6)
Cl2^ix—Rb2—Cl1^iv	118.82 (4)	Cu1^xv—Cl2—Rb1^xv	94.84 (7)
Cl2^iv—Rb2—Cl1^viii	118.82 (4)	Cu1^xv—Cl2—Rb2^xvii	94.93 (6)
Cl2^ix—Rb2—Cl2^x	61.77 (3)	Cu1^xv—Cl2—Rb2^xv	94.21 (6)
Cl2^iv—Rb2—Cl2^ix	111.13 (7)	Rb1^xii—Cl3—Rb1	168.98 (5)
Cl2^x—Rb2—Cl2^iii	125.91 (6)	Rb1—Cl3—Rb2	82.93 (4)
Cl2^iv—Rb2—Cl2^iii	61.77 (3)	Rb1^xii—Cl3—Rb2	86.91 (4)
Cl2^ix—Rb2—Cl2^iii	170.86 (5)	Rb2^xvii—Cl3—Rb1	90.11 (4)
Cl2^iv—Rb2—Cl2^x	170.86 (5)	Rb2^xvii—Cl3—Rb1^xii	97.55 (4)
Cl2^iii—Rb2—Cl3	92.43 (4)	Rb2^xvii—Cl3—Rb2	111.14 (5)
Cl2^ix—Rb2—Cl3	88.46 (4)	Cu1^xiv—Cl3—Rb1^xii	93.60 (6)
Cl2^iv—Rb2—Cl3	61.00 (4)	Cu1^xiv—Cl3—Rb1	93.44 (5)
Cl2^x—Rb2—Cl3^xi	92.43 (4)	Cu1^xiv—Cl3—Rb2	152.40 (6)
Cl2^x—Rb2—Cl3	111.66 (4)	Cu1^xiv—Cl3—Rb2^xvii	96.18 (7)
Cl2^iii—Rb2—Cl3^xi	111.66 (4)	Rb1^xviii—Cl4—Rb1	179.24 (10)
Cl2^ix—Rb2—Cl3^xi	61.00 (4)	Rb2^v—Cl4—Rb1^xviii	89.62 (5)
Cl2^iv—Rb2—Cl3^xi	88.46 (4)	Rb2^v—Cl4—Rb1	89.62 (5)
Cl2^ix—Rb2—Cl4^viii	124.44 (3)	Rb2^xvi—Cl4—Rb1^xviii	90.38 (5)
Cl2^ix—Rb2—Cl4^xii	55.56 (3)	Rb2^xvi—Cl4—Rb1	90.38 (5)
Cl2^iv—Rb2—Cl4^viii	124.44 (3)	Rb2^v—Cl4—Rb2^xvi	180.0
Cl2^x—Rb2—Cl4^viii	62.96 (3)	Cu1^xix—Cl4—Rb1^xviii	88.41 (4)
Cl2^iii—Rb2—Cl4^viii	62.96 (3)	Cu1^v—Cl4—Rb1	88.41 (4)
Cl2^iv—Rb2—Cl4^xii	55.56 (3)	Cu1^v—Cl4—Rb1^xviii	91.61 (4)
Cl3^x—Rb2—Cl1^viii	116.40 (4)	Cu1^xix—Cl4—Rb1	91.61 (4)
Cl3^iii—Rb2—Cl1^iv	116.40 (4)	Cu1^xix—Cl4—Rb2^v	91.26 (7)
Cl3^x—Rb2—Cl1^iv	61.99 (4)	Cu1^v—Cl4—Rb2^xvi	88.74 (7)
Cl3^iii—Rb2—Cl1^viii	61.99 (4)	Cu1^v—Cl4—Rb2^v	91.26 (7)
Cl3^iii—Rb2—Cl2^iv	93.90 (4)	Cu1^xix—Cl4—Rb2^xvi	88.74 (7)
Cl3^iii—Rb2—Cl2^iii	63.15 (4)	Cu1^xix—Cl4—Cu1^v	177.49 (14)

Symmetry codes: (i) x−1, y, z; (ii) x−1/2, −y+1/2, −z+1; (iii) −x, y, −z+1/2; (iv) −x+1/2, −y+1/2, z−1/2; (v) x−1/2, y+1/2, z; (vi) −x+1/2, y+1/2, −z+1/2; (vii) −x, −y+1, z+1/2; (viii) x−1/2, y−1/2, z; (ix) −x+1/2, y−1/2, −z+1/2; (x) −x, −y, z−1/2; (xi) x, −y, −z; (xii) x+1/2, y−1/2, z; (xiii) x+1, y, z; (xiv) −x+1, y, −z+1/2; (xv) −x+1/2, −y+1/2, z+1/2; (xvi) x+1/2, y+1/2, z; (xvii) −x, −y, z+1/2; (xviii) −x, −y+1, z−1/2; (xix) x−1/2, −y+1/2, −z.