Redetermination of potassium chloro­chromate, KCrO₃Cl

KCrO₃Cl, potassium trioxo­chloro­chromate(VI), has been redetermined from room-temperature single-crystal X-ray data. The Cr atom is tetrahedrally coordinated by three O atoms (average Cr-O bond length 1.597 Å) and one Cl atom at 2.1916 (8) Å, with nearly ideal tetrahedral angles. The K ion is coordinated by eight O and three Cl atoms. Isolated CrO₃Cl tetrahedra and K ions are connected via common ligands. All atoms are in general positions.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](Cr-O) = 0.002 Å
• R factor = 0.028
• wR factor = 0.079
• Data-to-parameter ratio = 19.7

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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Computing details

Data collection: COLLECT (Nonius, 2001); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ATOMS (Shape Software, 1999) and ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

potassium trioxochloro(I)chromate(VI)

Crystal data

KCrO3Cl	F(000) = 336
Mr = 174.55	Dx = 2.528 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1435 reflections
a = 7.838 (2) Å	θ = 2.0–30.0°
b = 7.493 (1) Å	µ = 3.84 mm^−1
c = 7.812 (2) Å	T = 293 K
β = 91.40 (3)°	Tabular, brown–orange
V = 458.66 (18) Å^3	0.20 × 0.10 × 0.02 mm
Z = 4

Data collection

Nonius KappaCCD diffractometer	1102 independent reflections
Radiation source: fine-focus sealed tube	924 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.015
ω scans	θmax = 27.9°, θmin = 2.6°
Absorption correction: multi-scan (HKL SCALEPACK; Otwinowski & Minor, 1997)	h = −10→10
Tmin = 0.514, Tmax = 0.927	k = −9→9
2117 measured reflections	l = −10→10

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.028	w = 1/[σ^2(Fo^2) + (0.04P)^2 + 0.08P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.079	(Δ/σ)max = 0.001
S = 1.16	Δρmax = 0.57 e Å^−3
1102 reflections	Δρmin = −0.38 e Å^−3
56 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.015 (2)

Special details

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
K	0.30127 (8)	0.63961 (7)	0.86872 (6)	0.03601 (19)
Cr	0.28241 (5)	0.12435 (4)	0.87486 (4)	0.02481 (16)
Cl	0.04765 (8)	0.28306 (8)	0.85952 (8)	0.0406 (2)
O1	0.4366 (2)	0.2626 (2)	0.8906 (3)	0.0479 (5)
O2	0.2965 (2)	0.0072 (2)	0.7049 (2)	0.0457 (5)
O3	0.2764 (3)	−0.0052 (2)	1.0374 (2)	0.0493 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
K	0.0489 (4)	0.0303 (3)	0.0287 (3)	−0.0019 (2)	−0.0029 (3)	−0.00078 (18)
Cr	0.0256 (3)	0.0236 (2)	0.0252 (2)	−0.00018 (13)	0.00016 (17)	−0.00001 (12)
Cl	0.0309 (3)	0.0416 (4)	0.0491 (4)	0.0069 (2)	−0.0001 (3)	−0.0004 (3)
O1	0.0342 (10)	0.0367 (10)	0.0724 (13)	−0.0082 (8)	−0.0048 (9)	−0.0026 (9)
O2	0.0501 (12)	0.0480 (11)	0.0388 (9)	0.0106 (9)	−0.0010 (8)	−0.0146 (8)
O3	0.0530 (12)	0.0519 (12)	0.0435 (10)	0.0119 (9)	0.0096 (9)	0.0195 (9)

Geometric parameters (Å, º)

K—O3^i	2.7798 (18)	Cr—O3	1.5997 (17)
K—O1^ii	2.847 (2)	Cr—Cl	2.1916 (8)
K—O2^iii	2.8485 (18)	Cr—K^viii	3.6356 (8)
K—O3^iv	2.979 (2)	Cr—K^ix	3.8191 (14)
K—O1	3.0210 (19)	Cl—K^x	3.4023 (13)
K—O2^iv	3.037 (2)	Cl—K^vii	3.5505 (14)
K—O1^v	3.063 (2)	O1—K^ii	2.847 (2)
K—Cl	3.3297 (9)	O1—K^ix	3.063 (2)
K—O2^v	3.368 (2)	O2—K^i	2.8485 (18)
K—Cl^vi	3.4023 (13)	O2—K^viii	3.037 (2)
K—Cl^vii	3.5505 (14)	O2—K^ix	3.368 (2)
K—Cr^iv	3.6356 (8)	O3—K^iii	2.7798 (18)
Cr—O1	1.5938 (18)	O3—K^viii	2.979 (2)
Cr—O2	1.5977 (16)
O3^i—K—O1^ii	137.83 (6)	O3^iv—K—Cl^vi	83.64 (4)
O3^i—K—O2^iii	135.75 (6)	O1—K—Cl^vi	126.99 (4)
O1^ii—K—O2^iii	61.06 (6)	O2^iv—K—Cl^vi	59.42 (4)
O3^i—K—O3^iv	137.05 (6)	O1^v—K—Cl^vi	95.86 (4)
O1^ii—K—O3^iv	62.07 (5)	Cl—K—Cl^vi	76.72 (2)
O2^iii—K—O3^iv	86.26 (5)	O2^v—K—Cl^vi	138.37 (4)
O3^i—K—O1	74.35 (6)	O3^i—K—Cl^vii	125.34 (5)
O1^ii—K—O1	87.52 (5)	O1^ii—K—Cl^vii	96.73 (5)
O2^iii—K—O1	66.37 (6)	O2^iii—K—Cl^vii	58.94 (5)
O3^iv—K—O1	146.86 (6)	O3^iv—K—Cl^vii	61.97 (4)
O3^i—K—O2^iv	86.36 (5)	O1—K—Cl^vii	113.16 (4)
O1^ii—K—O2^iv	92.64 (5)	O2^iv—K—Cl^vii	95.87 (4)
O2^iii—K—O2^iv	137.60 (5)	O1^v—K—Cl^vii	152.32 (4)
O3^iv—K—O2^iv	51.37 (5)	Cl—K—Cl^vii	71.08 (2)
O1—K—O2^iv	150.77 (6)	O2^v—K—Cl^vii	152.64 (4)
O3^i—K—O1^v	61.70 (6)	Cl^vi—K—Cl^vii	68.95 (2)
O1^ii—K—O1^v	82.78 (5)	O1—Cr—O2	110.70 (11)
O2^iii—K—O1^v	138.61 (6)	O1—Cr—O3	111.70 (11)
O3^iv—K—O1^v	94.36 (5)	O2—Cr—O3	109.29 (10)
O1—K—O1^v	94.50 (4)	O1—Cr—Cl	106.59 (7)
O2^iv—K—O1^v	56.63 (5)	O2—Cr—Cl	109.13 (7)
O3^i—K—Cl	70.18 (4)	O3—Cr—Cl	109.38 (7)
O1^ii—K—Cl	129.92 (4)	K—Cl—K^vii	108.92 (2)
O2^iii—K—Cl	71.87 (4)	K^x—Cl—K^vii	75.16 (3)
O3^iv—K—Cl	132.93 (5)	Cr—O1—K^ii	138.75 (11)
O1—K—Cl	57.28 (4)	Cr—O1—K	109.81 (9)
O2^iv—K—Cl	135.84 (4)	K^ii—O1—K	92.48 (5)
O1^v—K—Cl	129.57 (4)	Cr—O1—K^ix	105.85 (9)
O3^i—K—O2^v	77.22 (6)	K^ii—O1—K^ix	91.67 (6)
O1^ii—K—O2^v	61.64 (6)	K—O1—K^ix	118.96 (6)
O2^iii—K—O2^v	94.42 (6)	Cr—O2—K^i	168.85 (10)
O3^iv—K—O2^v	114.22 (6)	Cr—O2—K^viii	98.54 (8)
O1—K—O2^v	53.52 (5)	K^i—O2—K^viii	92.17 (5)
O2^iv—K—O2^v	101.37 (4)	Cr—O2—K^ix	93.68 (8)
O1^v—K—O2^v	47.90 (5)	K^i—O2—K^ix	85.58 (6)
Cl—K—O2^v	108.71 (4)	K^viii—O2—K^ix	109.70 (6)
O3^i—K—Cl^vi	65.76 (5)	Cr—O3—K^iii	162.97 (12)
O1^ii—K—Cl^vi	145.35 (4)	Cr—O3—K^viii	100.80 (8)
O2^iii—K—Cl^vi	125.22 (5)	K^iii—O3—K^viii	94.83 (5)

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