Tetra­samarium(II) oxide hexa­iodide, Sm₄OI₆

Black single crystals of tetra­samarium(II) oxide hexa­iodide, Sm₄OI₆, were obtained from a reaction of SmI₃, SmOI, NaI, and Na in a sealed tantalum container. Sm₄OI₆ crystallizes in space group P6₃mc and, like many M₄OX₆ type oxide halides of divalent metals, adopts the anti-K₆HgS₄/Na₆ZnO₄ type of structure, with K₆HgS₄ ≃ I₆OSm₄. A tetra­hedron of samarium(II) that incorporates an oxide ion is surrounded by 18 iodide ions which are connected further into a three-dimensional non-centrosymmetric structure. The O atom and one of the Sm atoms occupy sites with 3m symmetry, whereas the second Sm atom and both I atoms are located at sites with m symmetry.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](m-O) = 0.014 Å
• R factor = 0.042
• wR factor = 0.104
• Data-to-parameter ratio = 36.8

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT199_ALERT_1_C Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_C Check the Reported _diffrn_ambient_temperature .        293 K
PLAT731_ALERT_1_C Bond    Calc  3.4078(19), Rep   3.4078(8) ......       2.38 su-Rat
              SM1  -I1      1.555   5.655

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           32.20
           From the CIF: _reflns_number_total                957
           Count of symmetry unique reflns          548
           Completeness (_total/calc)            174.64%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       409
           Fraction of Friedel pairs measured     0.746
           Are heavy atom types Z>Si present        yes

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   3 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion

---

Computing details

Data collection: X-AREA (Stoe & Cie, 2001); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 2001); software used to prepare material for publication: SHELXL97.

tetrasamarium hexaiodine oxygen

Crystal data

Sm4OI6	Dx = 6.027 Mg m^−3
Mr = 1378.80	Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P63mc	Cell parameters from 16703 reflections
Hall symbol: P 6c -2c	θ = 2.3–32.2°
a = 10.4415 (8) Å	µ = 27.38 mm^−1
c = 8.0464 (7) Å	T = 293 K
V = 759.73 (11) Å^3	Column, black
Z = 2	0.50 × 0.10 × 0.10 mm
F(000) = 1148

Data collection

Stoe IPDS-II diffractometer	957 independent reflections
Radiation source: fine-focus sealed tube	917 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.087
ω and φ scans	θmax = 32.2°, θmin = 2.3°
Absorption correction: numerical [X-RED32 (Stoe & Cie, 2001) and X-SHAPE (Stoe & Cie, 1999)]	h = −15→15
Tmin = 0.029, Tmax = 0.118	k = −15→15
17645 measured reflections	l = −9→12

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.0404P)^2 + 30.1615P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.042	(Δ/σ)max < 0.001
wR(F^2) = 0.104	Δρmax = 2.38 e Å^−3
S = 1.09	Δρmin = −1.61 e Å^−3
957 reflections	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
26 parameters	Extinction coefficient: 0.0108 (6)
1 restraint	Absolute structure: Flack (1983), 412 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.02 (6)

Special details

Experimental. A suitable single-crystal was carefully selected under a polarizing microscope and mounted in a glass capillary. The scattering intensities were collected on an imaging plate diffractometer (IPDS II, Stoe & Cie) equipped with a fine focus sealed tube X-ray source (Mo Kα, λ = 0.71073 Å) operating at 50 kV and 40 mA. Intensity data for the title compound were collected at room temperature by ω-scans in 180 frames (0 < ω < 180°; φ = O°, 0 < ω < 180°; φ = 90°, Δω = 2°, exposure time of 4 min) in the 2 Θ range 2.9 to 64.8°. Structure solution and refinement were carried out using the programs SIR92 (Altomare et al., 1993) and SHELXL97 (Sheldrick, 1997). A numerical absorption correction (X-RED (Stoe & Cie, 2001) was applied after optimization of the crystal shape (X-SHAPE (Stoe & Cie, 1999)). The last cycles of refinement included atomic positions and anisotropic parameters for all atoms. The final difference maps were free of any chemically significant features. The refinement was based on F² for ALL reflections.

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

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

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

	x	y	z	Uiso*/Ueq
Sm1	0.58957 (9)	0.79479 (4)	0.08851 (13)	0.0227 (2)
Sm2	0.3333	0.6667	−0.3024 (2)	0.0293 (4)
I1	0.73093 (13)	0.86546 (7)	−0.29042 (17)	0.0271 (3)
I2	0.06919 (13)	0.53459 (6)	−0.60632 (16)	0.0243 (3)
O1	0.3333	0.6667	−0.005 (3)	0.021 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Sm1	0.0207 (4)	0.0225 (3)	0.0243 (4)	0.01033 (19)	−0.0013 (4)	−0.00063 (19)
Sm2	0.0343 (5)	0.0343 (5)	0.0193 (7)	0.0172 (3)	0.000	0.000
I1	0.0313 (6)	0.0234 (4)	0.0292 (6)	0.0156 (3)	0.0037 (5)	0.0018 (2)
I2	0.0251 (5)	0.0249 (4)	0.0231 (6)	0.0125 (3)	0.0016 (4)	0.0008 (2)
O1	0.024 (6)	0.024 (6)	0.016 (10)	0.012 (3)	0.000	0.000

Geometric parameters (Å, º)

Sm1—O1	2.436 (7)	Sm2—I2^viii	3.4184 (19)
Sm1—I1	3.3061 (17)	Sm2—I1^viii	3.5966 (13)
Sm1—I2^i	3.4013 (13)	Sm2—I1	3.5966 (13)
Sm1—I2^ii	3.4013 (13)	Sm2—I1^vii	3.5966 (13)
Sm1—I1^iii	3.4078 (8)	Sm2—Sm1^viii	3.9068 (18)
Sm1—I1^iv	3.4078 (8)	Sm2—Sm1^vii	3.9068 (18)
Sm1—I2^v	3.5554 (11)	I1—Sm1^ix	3.4078 (8)
Sm1—I2^vi	3.5554 (11)	I1—Sm1^x	3.4078 (8)
Sm1—Sm2	3.9068 (18)	I2—Sm1^xi	3.4013 (13)
Sm1—Sm1^vii	4.0133 (14)	I2—Sm1^xii	3.4013 (13)
Sm1—Sm1^viii	4.0133 (14)	I2—Sm1^xiii	3.5554 (11)
Sm2—O1	2.39 (2)	I2—Sm1^xiv	3.5554 (11)
Sm2—I2	3.4184 (19)	O1—Sm1^viii	2.436 (7)
Sm2—I2^vii	3.4184 (19)	O1—Sm1^vii	2.436 (7)
O1—Sm1—I1	94.7 (5)	O1—Sm2—I1^viii	88.46 (4)
O1—Sm1—I2^i	84.8 (4)	I2—Sm2—I1^viii	70.73 (2)
I1—Sm1—I2^i	142.50 (2)	I2^vii—Sm2—I1^viii	70.73 (2)
O1—Sm1—I2^ii	84.8 (4)	I2^viii—Sm2—I1^viii	135.86 (6)
I1—Sm1—I2^ii	142.51 (2)	O1—Sm2—I1	88.46 (4)
I2^i—Sm1—I2^ii	74.91 (5)	I2—Sm2—I1	135.86 (6)
O1—Sm1—I1^iii	141.68 (5)	I2^vii—Sm2—I1	70.73 (2)
I1—Sm1—I1^iii	88.89 (3)	I2^viii—Sm2—I1	70.73 (2)
I2^i—Sm1—I1^iii	114.29 (4)	I1^viii—Sm2—I1	119.929 (4)
I2^ii—Sm1—I1^iii	70.08 (3)	O1—Sm2—I1^vii	88.46 (4)
O1—Sm1—I1^iv	141.68 (5)	I2—Sm2—I1^vii	70.73 (2)
I1—Sm1—I1^iv	88.89 (3)	I2^vii—Sm2—I1^vii	135.86 (6)
I2^i—Sm1—I1^iv	70.08 (3)	I2^viii—Sm2—I1^vii	70.73 (2)
I2^ii—Sm1—I1^iv	114.29 (4)	I1^viii—Sm2—I1^vii	119.929 (4)
I1^iii—Sm1—I1^iv	76.39 (5)	I1—Sm2—I1^vii	119.929 (4)
O1—Sm1—I2^v	74.4 (2)	O1—Sm2—Sm1^viii	36.38 (2)
I1—Sm1—I2^v	69.35 (3)	I2—Sm2—Sm1^viii	111.64 (2)
I2^i—Sm1—I2^v	144.23 (3)	I2^vii—Sm2—Sm1^viii	111.64 (2)
I2^ii—Sm1—I2^v	74.513 (12)	I2^viii—Sm2—Sm1^viii	172.05 (5)
I1^iii—Sm1—I2^v	71.35 (3)	I1^viii—Sm2—Sm1^viii	52.09 (3)
I1^iv—Sm1—I2^v	140.95 (3)	I1—Sm2—Sm1^viii	105.95 (4)
O1—Sm1—I2^vi	74.4 (2)	I1^vii—Sm2—Sm1^viii	105.95 (4)
I1—Sm1—I2^vi	69.35 (3)	O1—Sm2—Sm1	36.38 (2)
I2^i—Sm1—I2^vi	74.513 (12)	I2—Sm2—Sm1	172.05 (5)
I2^ii—Sm1—I2^vi	144.23 (3)	I2^vii—Sm2—Sm1	111.64 (2)
I1^iii—Sm1—I2^vi	140.95 (3)	I2^viii—Sm2—Sm1	111.64 (2)
I1^iv—Sm1—I2^vi	71.35 (3)	I1^viii—Sm2—Sm1	105.95 (4)
I2^v—Sm1—I2^vi	124.89 (5)	I1—Sm2—Sm1	52.09 (3)
O1—Sm1—Sm2	35.6 (5)	I1^vii—Sm2—Sm1	105.95 (4)
I1—Sm1—Sm2	59.12 (3)	Sm1^viii—Sm2—Sm1	61.81 (3)
I2^i—Sm1—Sm2	112.67 (3)	O1—Sm2—Sm1^vii	36.38 (2)
I2^ii—Sm1—Sm2	112.67 (3)	I2—Sm2—Sm1^vii	111.64 (2)
I1^iii—Sm1—Sm2	131.63 (3)	I2^vii—Sm2—Sm1^vii	172.05 (5)
I1^iv—Sm1—Sm2	131.63 (3)	I2^viii—Sm2—Sm1^vii	111.64 (2)
I2^v—Sm1—Sm2	64.03 (2)	I1^viii—Sm2—Sm1^vii	105.95 (4)
I2^vi—Sm1—Sm2	64.03 (2)	I1—Sm2—Sm1^vii	105.95 (4)
O1—Sm1—Sm1^vii	34.5 (2)	I1^vii—Sm2—Sm1^vii	52.09 (3)
I1—Sm1—Sm1^vii	109.56 (2)	Sm1^viii—Sm2—Sm1^vii	61.81 (3)
I2^i—Sm1—Sm1^vii	53.846 (19)	Sm1—Sm2—Sm1^vii	61.81 (3)
I2^ii—Sm1—Sm1^vii	91.04 (2)	Sm1—I1—Sm1^ix	109.22 (3)
I1^iii—Sm1—Sm1^vii	160.59 (3)	Sm1—I1—Sm1^x	109.22 (3)
I1^iv—Sm1—Sm1^vii	108.96 (2)	Sm1^ix—I1—Sm1^x	141.18 (5)
I2^v—Sm1—Sm1^vii	108.795 (18)	Sm1—I1—Sm2	68.79 (4)
I2^vi—Sm1—Sm1^vii	55.640 (17)	Sm1^ix—I1—Sm2	99.31 (3)
Sm2—Sm1—Sm1^vii	59.094 (17)	Sm1^x—I1—Sm2	99.31 (3)
O1—Sm1—Sm1^viii	34.5 (2)	Sm1^xi—I2—Sm1^xii	72.31 (4)
I1—Sm1—Sm1^viii	109.56 (2)	Sm1^xi—I2—Sm2	105.29 (3)
I2^i—Sm1—Sm1^viii	91.04 (2)	Sm1^xii—I2—Sm2	105.29 (3)
I2^ii—Sm1—Sm1^viii	53.846 (19)	Sm1^xi—I2—Sm1^xiii	103.75 (3)
I1^iii—Sm1—Sm1^viii	108.96 (2)	Sm1^xii—I2—Sm1^xiii	154.64 (5)
I1^iv—Sm1—Sm1^viii	160.59 (3)	Sm2—I2—Sm1^xiii	99.92 (4)
I2^v—Sm1—Sm1^viii	55.640 (17)	Sm1^xi—I2—Sm1^xiv	154.64 (5)
I2^vi—Sm1—Sm1^viii	108.795 (18)	Sm1^xii—I2—Sm1^xiv	103.75 (3)
Sm2—Sm1—Sm1^viii	59.094 (17)	Sm2—I2—Sm1^xiv	99.92 (4)
Sm1^vii—Sm1—Sm1^viii	60.0	Sm1^xiii—I2—Sm1^xiv	68.72 (3)
O1—Sm2—I2	135.67 (3)	Sm2—O1—Sm1^viii	108.0 (5)
O1—Sm2—I2^vii	135.67 (3)	Sm2—O1—Sm1	108.0 (5)
I2—Sm2—I2^vii	74.48 (5)	Sm1^viii—O1—Sm1	110.9 (5)
O1—Sm2—I2^viii	135.67 (3)	Sm2—O1—Sm1^vii	108.0 (5)
I2—Sm2—I2^viii	74.48 (5)	Sm1^viii—O1—Sm1^vii	110.9 (5)
I2^vii—Sm2—I2^viii	74.48 (5)	Sm1—O1—Sm1^vii	110.9 (5)

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