Hexa­carbonyl­chromium(0) at 11 K

The crystal structure of hexa­carbonyl­chromium(0), [Cr(CO)₆], has been refined with an accurate and extensive X-ray data set collected at 11 K. This data set should be suitable for charge-density analysis studies. The structure is made up of isolated Cr(CO)₆ mol­ecules of very near octahedral symmetry, containing a crystallographic mirror plane.

Key indicators

• Single-crystal X-ray study
• T = 11 K
• Mean [sigma](O-C) = 0.001 Å
• R factor = 0.020
• wR factor = 0.054
• Data-to-parameter ratio = 61.9

checkCIF/PLATON results

No syntax errors found



Alert level C
CELLK01_ALERT_1_C  Check that the cell measurement temperature is in Kelvin.
            Value of measurement temperature given =    11.000
PLAT040_ALERT_1_C No H-atoms in this Carbon Containing Compound ..          ?
PLAT230_ALERT_2_C Hirshfeld Test Diff for    O4     -   C4      ..       5.43 su

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

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 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
   0 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: Local diffractometer control software; cell refinement: Local diffractometer control software; data reduction: PROFIT (Streltsov & Zavodnik, 1989); program(s) used to solve structure: SHELXTL (Bruker, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Hexacarbonylchromium(0)

Crystal data

[Cr(CO)6]	Dx = 1.890 Mg m^−3
Mr = 220.06	Melting point: not measured K
Orthorhombic, Pnma	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2n	Cell parameters from 14 reflections
a = 11.474 (1) Å	θ = 31.4–38.7°
b = 10.894 (1) Å	µ = 1.47 mm^−1
c = 6.1885 (4) Å	T = 11 K
V = 773.55 (11) Å^3	Prism, pale yellow
Z = 4	0.46 × 0.40 × 0.40 mm
F(000) = 432

Data collection

Huber 512 goniometer diffractometer	4125 reflections with I > 2σ(I)
Radiation source: normal-focus sealed tube	Rint = 0.023
None monochromator	θmax = 50.1°, θmin = 3.6°
ω–2θ scans	h = −24→24
Absorption correction: gaussian (Xtal3.7; ,Hall et al., 2000)	k = −23→23
Tmin = 0.564, Tmax = 0.639	l = −13→13
27649 measured reflections	3 standard reflections every 100 reflections
4212 independent reflections	intensity decay: 1%

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)] = 0.020	w = 1/[σ^2(Fo^2) + (0.0244P)^2 + 0.21P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.054	(Δ/σ)max = 0.001
S = 1.14	Δρmax = 0.84 e Å^−3
4212 reflections	Δρmin = −1.00 e Å^−3
68 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.069 (2)

Special details

Experimental. The correction for the absorption by the beryllium shield was performed by PROFIT (Streltsov & Zavodnik, 1989) program.

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
Cr	0.372617 (6)	0.2500	0.061768 (12)	0.00389 (2)
O1	0.22594 (4)	0.2500	0.47381 (8)	0.01039 (6)
O2	0.51645 (4)	0.2500	−0.35446 (7)	0.01016 (6)
O3	0.53222 (3)	0.44722 (3)	0.25104 (6)	0.01015 (4)
O4	0.21774 (3)	0.45103 (3)	−0.13004 (6)	0.01033 (4)
C1	0.28088 (4)	0.2500	0.31970 (8)	0.00716 (6)
C2	0.46326 (4)	0.2500	−0.19848 (8)	0.00715 (6)
C3	0.47212 (3)	0.37382 (3)	0.18108 (6)	0.00707 (4)
C4	0.27474 (3)	0.37558 (3)	−0.05848 (6)	0.00710 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cr	0.00430 (3)	0.00355 (3)	0.00383 (3)	0.000	−0.00003 (2)	0.000
O1	0.01062 (14)	0.01285 (15)	0.00771 (12)	0.000	0.00275 (11)	0.000
O2	0.01084 (14)	0.01226 (15)	0.00737 (12)	0.000	0.00274 (11)	0.000
O3	0.01047 (10)	0.00890 (10)	0.01109 (10)	−0.00290 (8)	−0.00135 (8)	−0.00117 (8)
O4	0.01011 (10)	0.00887 (10)	0.01202 (10)	0.00248 (8)	−0.00109 (8)	0.00252 (8)
C1	0.00746 (14)	0.00738 (14)	0.00666 (14)	0.000	0.00037 (11)	0.000
C2	0.00761 (14)	0.00734 (14)	0.00649 (14)	0.000	0.00042 (11)	0.000
C3	0.00736 (10)	0.00656 (10)	0.00730 (10)	−0.00044 (8)	−0.00025 (8)	−0.00021 (8)
C4	0.00736 (10)	0.00665 (10)	0.00730 (10)	0.00040 (8)	−0.00004 (8)	0.00051 (8)

Geometric parameters (Å, º)

Cr—C1	1.9121 (5)	Cr—C4^i	1.9201 (4)
Cr—C2	1.9171 (5)	C1—O1	1.1432 (7)
Cr—C3	1.9152 (4)	C2—O2	1.1421 (7)
Cr—C3^i	1.9152 (4)	C3—O3	1.1412 (5)
Cr—C4	1.9201 (4)	C4—O4	1.1399 (5)
Cr—C1—O1	179.94 (5)	C2—Cr—C3^i	90.03 (2)
Cr—C2—O2	179.45 (5)	C2—Cr—C4	89.53 (2)
Cr—C3—O3	179.38 (4)	C2—Cr—C4^i	89.53 (2)
Cr—C4—O4	179.19 (3)	C3—Cr—C3^i	89.54 (2)
C1—Cr—C2	179.45 (2)	C3—Cr—C4	89.79 (2)
C1—Cr—C3	90.36 (2)	C3—Cr—C4^i	179.20 (2)
C1—Cr—C3^i	90.36 (2)	C3^i—Cr—C4^i	89.79 (2)
C1—Cr—C4	90.09 (2)	C3^i—Cr—C4	179.20 (2)
C1—Cr—C4^i	90.09 (2)	C4^i—Cr—C4	90.88 (2)
C2—Cr—C3	90.03 (2)

Symmetry code: (i) x, −y+1/2, z.