(η⁶-Bi­phenyl)­tri­carbonyl­chromium and μ-(η⁶:η⁶)-bi­phenyl-bis­(tricarbonyl­chromium)

The title compounds, [Cr(C₁₂H₁₀)(CO)₃] and [Cr₂(C₁₂H₁₀)(CO)₆], serve as a fundamental standard of comparison for other mono- and polysubstituted (η⁶-bi­phenyl)­tri­carbonyl­chromium compounds. (η⁶-Bi­phenyl)­tri­carbonyl­chromium has a typical piano-stool coordination about the Cr center, and the dihedral angle between the planes of the phenyl rings is 23.55 (5)°. The corresponding angle in μ-(η⁶:η⁶)-bi­phenyl-bis­(tri­carbonyl­chromium) is 0° because the mol­ecule occupies a crystallographic inversion center; the Cr atoms reside on opposite sides of the bi­phenyl ligand. Density functional theory and natural bonding orbital theory analyses were used to scrutinize the geometry of these and closely related compounds to explain important structural features.

S1. Comment

As part of an ongoing study of ortho-substituted (biphenyl)tricarbonylchromium compounds we became interested in (η⁶-biphenyl)tricarbonylchromium, (I), since it is the simplest unsubstituted version of all other mono- or polysubstituted compounds in the series. Recently, polysubstituted analogs of (I) have been used in stereoselective syntheses of biologically important molecules (Kamikawa et al., 2003; Fogel et al., 2001), and metal carbene benzannulation reactions (Kretschik et al., 1996), and the (η⁶-biphenyl)dicarbonylchromium fragment has been incorporated into Fischer carbene complexes (Merlic et al., 1992). Suprisingly, the solid-state structure of the unsubstituted analog (I) has not been reported to date, though several methods for its synthesis have been described previously (Fischer et al., 1959; Ercoli et al., 1959; Rieke et al., 1982). The importance of this compound as a fundamental standard of comparison for other mono- and polysubstituted (η⁶-biphenyl)tricarbonylchromium compounds prompted us to explore the solid-state structure of (I), which is reported here.

We first became interested in (I) because it relates to the structure of the brominated analog (η⁶-2-bromo-1,1'-biphenyl)tricarbonylchromium, (II), which we reported previously (Czerwinski et al., 2003). We found that (II) reacts with tert-butyl lithium at 195 K in ether in a metal–halogen exchange reaction that forms (I) in \sim10% yield after protonation with methanol. In an effort to prepare an authentic sample of (I) for comparison, a 1:1 mixture of biphenyl and chromium hexacarbonyl was refluxed in dibutyl ether/tetrahydrofuran (Nicholls & Whiting, 1959). Unexpectedly, the ¹H NMR spectrum of the resulting crude yellow solid showed that the product was a mixture containing 70% of the desired compound (I) and 30% of (η⁶:η⁶-biphenyl)bis(tricarbonylchromium), (III). Recrystallization from hexane/ether led to the formation of some single crystals of (III) but was not an efficient method for effecting complete separation of the two compounds. However, they have markedly different polarities and were readily separated using thin layer chromatography (Top & Jaouen, 1979). Slow evaporation of a hexane/ether solution of (I) led to single crystals suitable for crystallographic analysis.

We also report the structure of (III), which crystallizes in space group P2₁/c. We include atomic coordinates for the monoclinic cell that were not reported in a previous study, which showed that (II) crystallizes in two different space groups, P1 and P2₁/c (Corradini & Allegra, 1960). Compound (III) has attracted attention recently in electrochemical reactions leading to substituted biphenyl compounds (Rieke, 1992), and substituted variations of (III) have been the subject of crystallographic studies related to the electrochemistry (Pierce & Geiger, 1994) and novel coupling reactions (Rosemunch et al., 1991; Uemura et al., 1994) of (arene)tricarbonylchromium compounds.

Because of the importance of (I) and (III), we scrutinized their solid-state geometries and performed density functonal theory (DFT) studies of (I) and (III), referred to as (I-DFT) and (III-DFT), respectively, and of Cr(η-⁶C₆H₆)(CO)₃, (IV), with Gaussian98 (Frisch et al., 1998). Selected geometric parameters are presented in Table 1, while selected bond lengths and bond angles are tabulated in Tables 2 and 3. Literature data for the relevant bond distances in related complexes reported to the Cambridge Structural Database (Allen, 2002) were previously compiled and analyzed by us (Czerwinski et al. 2003).

The Cr—C(O), Cr—C(Ph) and Cr—centroid(Ph) distances in (I) and (III) are in excellent agreement with one another, the corresponding parameters in (II) and the literature data for related complexes. Interestingly, in the structures of (I-DFT), (III-DFT) and (IV) optimized at the B3LYP/LANL2DZ level of theory, the Cr—C(O) distances are shorter (by 0.01–0.02 Å) than those in (I) and (III), while the Cr—C(Ph) distances are longer (by almost 0.1 Å) than the respective bond lengths in (I) and (III), a very substantial difference. It is noteworthy that the natural atomic charges of the Cr centers in (I-DFT), (III-DFT) and (IV) were calculated to be −0.87 in all three cases, a result not intuitively obvious since the formal metal oxidation state in these compounds is zero. The natural bond theory analysis revealed that the hybridization of the Cr atoms is sd² in (I-DFT) and (III-DFT), and sp^0.5d^4.5 in (IV), indicating contribution of the p orbitals in the latter case. However, it is not clear why the hybridization states would differ in these compounds.

The C—C distances [1.412 (12) and 1.414 (11) Å, respectively] in the ligated ring of the solid-state structures of (I) and (III) are, as expected, longer than those of an ideal benzene molecule. The corresponding value in (IV) is 1.415 (11) Å, confirming that the Cr—C interactions in all three cases are similar. Calculating the average C—C distances in the coordinated rings in (I-DFT) and (IV) may be misleading since the theoretical geometries indicate alternating bond lengths (1.43 and 1.42 Å) in all three cases.

The ipso-C—ipso-C distances in (I), (II), (III), (I-DFT), (III-DFT) and the free biphenyl molecule optimized at the B3LYP/6–311++G** level of theory are 1.488 (2), 1.497 (3), 1.493 (3), 1.488, 1.486 and 1.486 Å, resepctively, and are not statistically different, despite the fact that the dihedral angles between the phenyl rings in these compounds are difference. The Ph–Ph dihedral angles in (I) and (I-DFT) differ dramatically (Table 1), but the value in (I-DFT) is closer to the theoretical value of the dihedral angle in free biphenyl (40.84°). In the solid-state structure of (III), the molecule occupies a crystallographic inversion center, which results in a 0° torsion angle between the phenyl rings.

S2. Experimental

A mixture of chromium hexacarbonyl (0.900 g, 4.09 mmol) and biphenyl (0.680 g, 4.02 mmol) in di-n-butyl ether (30 ml) and tetrahydrofuran (3 ml) was degassed and heated at reflux for 24 h under a nitrogen atmosphere. Tetrahydrofuran, di-n-butyl ether and the remaining unreacted chromium hexacarbonyl were removed by vacuum distillation. Purification of the remaining yellow residue by preparative thin layer chromatography (silica gel, 2:1 hexane:diethyl ether) gave a yellow band (Rf = 0.35) from which (I) was isolated as a yellow air-stable solid (0.722 g, 62% yield based on biphenyl) and an orange band (Rf = 0.15) from which (III) was isolated as a yellow air-stable solid (0.192 g, 11% yield based on biphenyl). Crystals of (I) were obtained by slow evaporation of a 3:1 hexane/ether solution and crystals of (III) were obtained by slow evaporation of a 1:1 hexane/ether solution.

S3. Refinement

All H atoms were included in the structure factor calculation at idealized positions and were allowed to ride on the neighboring atoms with relative isotropic displacement coefficients.

Computing details

For both compounds, data collection: SMART (Bruker, 2000–2003). Cell refinement: SAINT (Bruker, 2000–2003 for (I); SAINT (Bruker, 2000–2003) for (III). For both compounds, data reduction: SAINT. Program(s) used to solve structure: SHELXTL (Bruker, 2000–2003 for (I); SHELXTL (Bruker, 2000–2003) for (III). For both compounds, program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. The molecular structure of (I). Displacement ellipsoids are shown at 50% probability level.
	Fig. 2. The molecular structure of (III). Displacement ellipsoids are shown at 50% probability level.

(I) (η⁶-Biphenyl)tricarbonylchromium

Crystal data

[Cr(C12H10)(CO)3]	F(000) = 592
Mr = 290.23	Dx = 1.560 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 12.3982 (5) Å	Cell parameters from 8453 reflections
b = 7.1029 (3) Å	θ = 2.6–26.4°
c = 14.8428 (6) Å	µ = 0.92 mm^−1
β = 108.969 (1)°	T = 100 K
V = 1236.12 (9) Å^3	Block, yellow
Z = 4	0.38 × 0.32 × 0.28 mm

Data collection

Bruker SMART CCD area-detector diffractometer	2526 independent reflections
Radiation source: fine-focus sealed tube	2384 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.021
Detector resolution: n/a pixels mm^-1	θmax = 26.4°, θmin = 2.6°
ϕ and ω scans	h = −15→15
Absorption correction: multi-scan SADABS (Bruker-AXS, 2003)	k = −8→8
Tmin = 0.720, Tmax = 0.782	l = −18→18
13192 measured reflections

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)] = 0.025	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.072	H-atom parameters constrained
S = 1.07	w = 1/[σ^2(Fo^2) + (0.0425P)^2 + 0.6246P] where P = (Fo^2 + 2Fc^2)/3
2526 reflections	(Δ/σ)max = 0.001
172 parameters	Δρmax = 0.35 e Å^−3
0 restraints	Δρmin = −0.24 e Å^−3

Special details

Experimental. SADABS (Bruker-AXS, 2003)

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	0.484232 (18)	0.20290 (3)	0.278278 (15)	0.01388 (9)
O1	0.30699 (9)	0.07641 (16)	0.09698 (8)	0.0251 (2)
O2	0.65997 (9)	−0.03462 (16)	0.23383 (8)	0.0237 (2)
O3	0.43370 (10)	−0.13304 (16)	0.37952 (8)	0.0274 (3)
C1	0.46045 (12)	0.5032 (2)	0.22535 (10)	0.0164 (3)
C2	0.57766 (12)	0.4648 (2)	0.26722 (10)	0.0180 (3)
H2	0.6277	0.4859	0.2315	0.022*
C3	0.62240 (13)	0.3951 (2)	0.36162 (10)	0.0211 (3)
H3	0.7019	0.3720	0.3888	0.025*
C4	0.54983 (14)	0.3602 (2)	0.41500 (10)	0.0216 (3)
H4	0.5795	0.3131	0.4782	0.026*
C5	0.43164 (13)	0.3960 (2)	0.37354 (10)	0.0203 (3)
H5	0.3817	0.3724	0.4091	0.024*
C6	0.38778 (12)	0.4658 (2)	0.28074 (10)	0.0180 (3)
H6	0.3082	0.4887	0.2540	0.022*
C7	0.41420 (12)	0.5784 (2)	0.12666 (10)	0.0166 (3)
C8	0.48396 (13)	0.6779 (2)	0.08595 (11)	0.0188 (3)
H8	0.5621	0.6969	0.1215	0.023*
C9	0.44044 (14)	0.7494 (2)	−0.00613 (11)	0.0224 (3)
H9	0.4889	0.8163	−0.0330	0.027*
C10	0.32677 (15)	0.7233 (2)	−0.05865 (11)	0.0240 (3)
H10	0.2970	0.7725	−0.1214	0.029*
C11	0.25651 (13)	0.6249 (2)	−0.01921 (11)	0.0250 (3)
H11	0.1785	0.6066	−0.0552	0.030*
C12	0.29967 (12)	0.5530 (2)	0.07265 (11)	0.0213 (3)
H12	0.2507	0.4859	0.0990	0.026*
C13	0.37543 (12)	0.1237 (2)	0.16663 (10)	0.0181 (3)
C14	0.59135 (12)	0.0570 (2)	0.24974 (10)	0.0174 (3)
C15	0.45188 (12)	−0.0028 (2)	0.34008 (10)	0.0187 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cr	0.01313 (14)	0.01518 (15)	0.01401 (14)	−0.00096 (8)	0.00536 (10)	−0.00136 (8)
O1	0.0198 (5)	0.0286 (6)	0.0231 (5)	−0.0025 (4)	0.0017 (4)	−0.0070 (5)
O2	0.0181 (5)	0.0291 (6)	0.0252 (5)	0.0028 (4)	0.0087 (4)	−0.0033 (5)
O3	0.0322 (6)	0.0210 (6)	0.0355 (6)	0.0005 (5)	0.0199 (5)	0.0048 (5)
C1	0.0176 (6)	0.0138 (6)	0.0184 (7)	−0.0025 (5)	0.0069 (5)	−0.0040 (5)
C2	0.0167 (7)	0.0175 (7)	0.0198 (7)	−0.0041 (5)	0.0058 (6)	−0.0020 (5)
C3	0.0189 (7)	0.0195 (7)	0.0211 (7)	−0.0040 (6)	0.0013 (6)	−0.0024 (6)
C4	0.0294 (8)	0.0189 (7)	0.0145 (7)	−0.0021 (6)	0.0043 (6)	−0.0033 (6)
C5	0.0276 (8)	0.0170 (7)	0.0195 (7)	−0.0012 (6)	0.0120 (6)	−0.0037 (6)
C6	0.0184 (7)	0.0163 (7)	0.0204 (7)	0.0000 (5)	0.0080 (6)	−0.0033 (5)
C7	0.0190 (7)	0.0143 (6)	0.0176 (7)	0.0013 (5)	0.0072 (5)	−0.0019 (5)
C8	0.0203 (7)	0.0162 (7)	0.0211 (7)	−0.0006 (5)	0.0082 (6)	−0.0023 (5)
C9	0.0308 (8)	0.0172 (7)	0.0240 (8)	−0.0007 (6)	0.0152 (7)	−0.0006 (6)
C10	0.0335 (9)	0.0204 (8)	0.0175 (7)	0.0057 (6)	0.0077 (6)	0.0012 (6)
C11	0.0207 (7)	0.0282 (8)	0.0225 (7)	0.0024 (6)	0.0022 (6)	−0.0004 (6)
C12	0.0190 (7)	0.0236 (8)	0.0223 (7)	−0.0010 (6)	0.0079 (6)	0.0002 (6)
C13	0.0170 (7)	0.0168 (7)	0.0235 (7)	0.0010 (5)	0.0107 (6)	−0.0006 (6)
C14	0.0150 (6)	0.0208 (7)	0.0154 (6)	−0.0030 (6)	0.0037 (5)	−0.0005 (5)
C15	0.0171 (6)	0.0206 (7)	0.0206 (7)	0.0010 (6)	0.0090 (6)	−0.0038 (6)

Geometric parameters (Å, º)

Cr—C15	1.8374 (15)	C3—H3	0.9500
Cr—C14	1.8393 (15)	C4—C5	1.416 (2)
Cr—C13	1.8518 (15)	C4—H4	0.9500
Cr—C5	2.2148 (14)	C5—C6	1.397 (2)
Cr—C6	2.2240 (14)	C5—H5	0.9500
Cr—C3	2.2250 (14)	C6—H6	0.9500
Cr—C2	2.2252 (14)	C7—C12	1.397 (2)
Cr—C4	2.2259 (14)	C7—C8	1.397 (2)
Cr—C1	2.2592 (14)	C8—C9	1.392 (2)
O1—C13	1.1538 (18)	C8—H8	0.9500
O2—C14	1.1548 (18)	C9—C10	1.383 (2)
O3—C15	1.1555 (19)	C9—H9	0.9500
C1—C2	1.4090 (19)	C10—C11	1.386 (2)
C1—C6	1.4284 (19)	C10—H10	0.9500
C1—C7	1.488 (2)	C11—C12	1.390 (2)
C2—C3	1.418 (2)	C11—H11	0.9500
C2—H2	0.9500	C12—H12	0.9500
C3—C4	1.401 (2)
C15—Cr—C14	87.60 (6)	Cr—C2—H2	128.6
C15—Cr—C13	89.50 (6)	C4—C3—C2	120.25 (14)
C14—Cr—C13	89.61 (6)	C4—C3—Cr	71.69 (8)
C15—Cr—C5	90.94 (6)	C2—C3—Cr	71.43 (8)
C14—Cr—C5	151.70 (6)	C4—C3—H3	119.9
C13—Cr—C5	118.66 (6)	C2—C3—H3	119.9
C15—Cr—C6	116.97 (6)	Cr—C3—H3	129.4
C14—Cr—C6	155.40 (6)	C3—C4—C5	119.12 (13)
C13—Cr—C6	91.76 (6)	C3—C4—Cr	71.62 (8)
C5—Cr—C6	36.69 (5)	C5—C4—Cr	70.98 (8)
C15—Cr—C3	117.64 (6)	C3—C4—H4	120.4
C14—Cr—C3	89.46 (6)	C5—C4—H4	120.4
C13—Cr—C3	152.77 (6)	Cr—C4—H4	129.3
C5—Cr—C3	66.32 (6)	C6—C5—C4	120.56 (13)
C6—Cr—C3	78.27 (5)	C6—C5—Cr	72.02 (8)
C15—Cr—C2	154.79 (6)	C4—C5—Cr	71.84 (8)
C14—Cr—C2	91.25 (6)	C6—C5—H5	119.7
C13—Cr—C2	115.68 (6)	C4—C5—H5	119.7
C5—Cr—C2	78.33 (5)	Cr—C5—H5	128.7
C6—Cr—C2	66.11 (5)	C5—C6—C1	121.16 (13)
C3—Cr—C2	37.16 (5)	C5—C6—Cr	71.30 (8)
C15—Cr—C4	91.05 (6)	C1—C6—Cr	72.77 (8)
C14—Cr—C4	114.55 (6)	C5—C6—H6	119.4
C13—Cr—C4	155.84 (6)	C1—C6—H6	119.4
C5—Cr—C4	37.18 (6)	Cr—C6—H6	128.9
C6—Cr—C4	66.59 (5)	C12—C7—C8	118.27 (13)
C3—Cr—C4	36.69 (6)	C12—C7—C1	120.88 (13)
C2—Cr—C4	66.61 (5)	C8—C7—C1	120.84 (13)
C15—Cr—C1	154.08 (6)	C9—C8—C7	120.82 (14)
C14—Cr—C1	118.31 (6)	C9—C8—H8	119.6
C13—Cr—C1	90.06 (6)	C7—C8—H8	119.6
C5—Cr—C1	66.74 (5)	C10—C9—C8	120.20 (15)
C6—Cr—C1	37.15 (5)	C10—C9—H9	119.9
C3—Cr—C1	66.66 (5)	C8—C9—H9	119.9
C2—Cr—C1	36.62 (5)	C9—C10—C11	119.64 (14)
C4—Cr—C1	79.10 (5)	C9—C10—H10	120.2
C2—C1—C6	117.59 (13)	C11—C10—H10	120.2
C2—C1—C7	121.07 (12)	C10—C11—C12	120.34 (14)
C6—C1—C7	121.35 (13)	C10—C11—H11	119.8
C2—C1—Cr	70.38 (8)	C12—C11—H11	119.8
C6—C1—Cr	70.09 (8)	C11—C12—C7	120.73 (14)
C7—C1—Cr	130.25 (10)	C11—C12—H12	119.6
C1—C2—C3	121.31 (13)	C7—C12—H12	119.6
C1—C2—Cr	73.00 (8)	O1—C13—Cr	179.16 (13)
C3—C2—Cr	71.41 (8)	O2—C14—Cr	178.55 (12)
C1—C2—H2	119.3	O3—C15—Cr	178.70 (12)
C3—C2—H2	119.3
C15—Cr—C1—C2	134.54 (13)	C5—Cr—C4—C3	−131.07 (13)
C14—Cr—C1—C2	−46.89 (10)	C6—Cr—C4—C3	−102.13 (10)
C13—Cr—C1—C2	−136.47 (9)	C2—Cr—C4—C3	−29.20 (9)
C5—Cr—C1—C2	102.09 (9)	C1—Cr—C4—C3	−65.37 (9)
C6—Cr—C1—C2	130.69 (12)	C15—Cr—C4—C5	−90.17 (9)
C3—Cr—C1—C2	28.99 (8)	C14—Cr—C4—C5	−178.01 (9)
C4—Cr—C1—C2	65.26 (9)	C13—Cr—C4—C5	0.95 (19)
C15—Cr—C1—C6	3.85 (17)	C6—Cr—C4—C5	28.93 (9)
C14—Cr—C1—C6	−177.58 (8)	C3—Cr—C4—C5	131.07 (13)
C13—Cr—C1—C6	92.84 (9)	C2—Cr—C4—C5	101.86 (10)
C5—Cr—C1—C6	−28.60 (8)	C1—Cr—C4—C5	65.69 (9)
C3—Cr—C1—C6	−101.70 (9)	C3—C4—C5—C6	−0.2 (2)
C2—Cr—C1—C6	−130.69 (12)	Cr—C4—C5—C6	−55.17 (13)
C4—Cr—C1—C6	−65.43 (9)	C3—C4—C5—Cr	54.99 (12)
C15—Cr—C1—C7	−110.88 (16)	C15—Cr—C5—C6	−137.50 (9)
C14—Cr—C1—C7	67.70 (14)	C14—Cr—C5—C6	135.82 (13)
C13—Cr—C1—C7	−21.89 (13)	C13—Cr—C5—C6	−47.55 (11)
C5—Cr—C1—C7	−143.32 (14)	C3—Cr—C5—C6	102.54 (10)
C6—Cr—C1—C7	−114.72 (16)	C2—Cr—C5—C6	65.48 (9)
C3—Cr—C1—C7	143.57 (14)	C4—Cr—C5—C6	132.00 (13)
C2—Cr—C1—C7	114.58 (16)	C1—Cr—C5—C6	28.94 (8)
C4—Cr—C1—C7	179.84 (14)	C15—Cr—C5—C4	90.50 (9)
C6—C1—C2—C3	−1.3 (2)	C14—Cr—C5—C4	3.82 (17)
C7—C1—C2—C3	179.29 (13)	C13—Cr—C5—C4	−179.56 (9)
Cr—C1—C2—C3	−54.83 (13)	C6—Cr—C5—C4	−132.00 (13)
C6—C1—C2—Cr	53.54 (12)	C3—Cr—C5—C4	−29.47 (9)
C7—C1—C2—Cr	−125.88 (13)	C2—Cr—C5—C4	−66.52 (9)
C15—Cr—C2—C1	−132.98 (13)	C1—Cr—C5—C4	−103.07 (10)
C14—Cr—C2—C1	140.00 (9)	C4—C5—C6—C1	−0.2 (2)
C13—Cr—C2—C1	49.83 (10)	Cr—C5—C6—C1	−55.24 (12)
C5—Cr—C2—C1	−66.53 (8)	C4—C5—C6—Cr	55.08 (13)
C6—Cr—C2—C1	−30.05 (8)	C2—C1—C6—C5	0.9 (2)
C3—Cr—C2—C1	−132.54 (13)	C7—C1—C6—C5	−179.70 (13)
C4—Cr—C2—C1	−103.68 (9)	Cr—C1—C6—C5	54.56 (12)
C15—Cr—C2—C3	−0.44 (18)	C2—C1—C6—Cr	−53.69 (12)
C14—Cr—C2—C3	−87.46 (9)	C7—C1—C6—Cr	125.74 (13)
C13—Cr—C2—C3	−177.63 (9)	C15—Cr—C6—C5	49.28 (10)
C5—Cr—C2—C3	66.01 (9)	C14—Cr—C6—C5	−127.48 (14)
C6—Cr—C2—C3	102.49 (10)	C13—Cr—C6—C5	139.62 (9)
C4—Cr—C2—C3	28.86 (9)	C3—Cr—C6—C5	−65.93 (9)
C1—Cr—C2—C3	132.54 (13)	C2—Cr—C6—C5	−102.96 (10)
C1—C2—C3—C4	1.0 (2)	C4—Cr—C6—C5	−29.30 (9)
Cr—C2—C3—C4	−54.58 (13)	C1—Cr—C6—C5	−132.60 (13)
C1—C2—C3—Cr	55.56 (13)	C15—Cr—C6—C1	−178.11 (8)
C15—Cr—C3—C4	−48.07 (11)	C14—Cr—C6—C1	5.13 (18)
C14—Cr—C3—C4	−135.08 (10)	C13—Cr—C6—C1	−87.77 (9)
C13—Cr—C3—C4	136.82 (13)	C5—Cr—C6—C1	132.60 (13)
C5—Cr—C3—C4	29.84 (9)	C3—Cr—C6—C1	66.68 (8)
C6—Cr—C3—C4	66.40 (9)	C2—Cr—C6—C1	29.64 (8)
C2—Cr—C3—C4	132.14 (13)	C4—Cr—C6—C1	103.30 (9)
C1—Cr—C3—C4	103.55 (10)	C2—C1—C7—C12	156.35 (14)
C15—Cr—C3—C2	179.79 (8)	C6—C1—C7—C12	−23.1 (2)
C14—Cr—C3—C2	92.78 (9)	Cr—C1—C7—C12	66.56 (18)
C13—Cr—C3—C2	4.68 (17)	C2—C1—C7—C8	−24.3 (2)
C5—Cr—C3—C2	−102.31 (10)	C6—C1—C7—C8	156.31 (14)
C6—Cr—C3—C2	−65.75 (9)	Cr—C1—C7—C8	−114.08 (14)
C4—Cr—C3—C2	−132.14 (13)	C12—C7—C8—C9	−0.1 (2)
C1—Cr—C3—C2	−28.60 (8)	C1—C7—C8—C9	−179.51 (13)
C2—C3—C4—C5	−0.2 (2)	C7—C8—C9—C10	0.2 (2)
Cr—C3—C4—C5	−54.68 (12)	C8—C9—C10—C11	−0.2 (2)
C2—C3—C4—Cr	54.46 (13)	C9—C10—C11—C12	0.1 (2)
C15—Cr—C4—C3	138.76 (10)	C10—C11—C12—C7	0.0 (2)
C14—Cr—C4—C3	50.92 (11)	C8—C7—C12—C11	0.0 (2)
C13—Cr—C4—C3	−130.12 (15)	C1—C7—C12—C11	179.40 (14)

(III) [µ-(η⁶:η⁶)-biphenyl]bis(tricarbonylchromium)

Crystal data

[Cr2(C12H10)(CO)6]	F(000) = 428
Mr = 426.26	Dx = 1.780 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 10.7256 (12) Å	Cell parameters from 4396 reflections
b = 10.6894 (12) Å	θ = 2–25°
c = 7.1789 (8) Å	µ = 1.40 mm^−1
β = 104.875 (2)°	T = 100 K
V = 795.48 (15) Å^3	Block, orange
Z = 2	0.37 × 0.32 × 0.31 mm

Data collection

Bruker CCD 1000 area detector diffractometer	1943 independent reflections
Radiation source: fine-focus sealed tube	1838 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.025
Detector resolution: n/a pixels mm^-1	θmax = 28.3°, θmin = 2.7°
0.2 degree ω scans	h = −14→14
Absorption correction: multi-scan SADABS (Bruker-AXS, 2003)	k = −14→13
Tmin = 0.625, Tmax = 0.671	l = −9→9
7141 measured reflections

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)] = 0.032	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.091	H-atom parameters constrained
S = 1.09	w = 1/[σ^2(Fo^2) + (0.0539P)^2 + 0.5575P] where P = (Fo^2 + 2Fc^2)/3
1943 reflections	(Δ/σ)max < 0.001
118 parameters	Δρmax = 0.51 e Å^−3
0 restraints	Δρmin = −0.35 e Å^−3

Special details

Experimental. SADABS (Bruker-AXS, 2003)

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
Cr1	0.25978 (2)	−0.01521 (3)	0.07603 (4)	0.01094 (12)
O1	0.11777 (15)	−0.25967 (14)	−0.0045 (2)	0.0278 (3)
O2	0.42707 (13)	−0.12917 (14)	0.43620 (19)	0.0230 (3)
O3	0.08368 (12)	0.06744 (13)	0.31644 (19)	0.0205 (3)
C1	0.43330 (16)	0.02590 (16)	−0.0326 (3)	0.0129 (3)
C2	0.33848 (17)	−0.03262 (17)	−0.1802 (2)	0.0146 (3)
H2	0.3604	−0.1051	−0.2415	0.018*
C3	0.21096 (18)	0.01520 (17)	−0.2385 (3)	0.0153 (4)
H3	0.1481	−0.0264	−0.3363	0.018*
C4	0.17704 (17)	0.12335 (17)	−0.1528 (3)	0.0173 (4)
H4	0.0920	0.1560	−0.1931	0.021*
C5	0.27163 (18)	0.18344 (17)	−0.0049 (3)	0.0173 (4)
H5	0.2496	0.2569	0.0539	0.021*
C6	0.39746 (17)	0.13539 (16)	0.0554 (3)	0.0157 (3)
H6	0.4593	0.1761	0.1557	0.019*
C7	0.17248 (17)	−0.16632 (18)	0.0270 (3)	0.0171 (3)
C8	0.36423 (16)	−0.08471 (16)	0.2978 (3)	0.0147 (3)
C9	0.15005 (17)	0.03455 (17)	0.2229 (3)	0.0146 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cr1	0.01208 (18)	0.01074 (17)	0.01055 (18)	−0.00057 (9)	0.00391 (12)	0.00034 (9)
O1	0.0341 (8)	0.0177 (7)	0.0298 (8)	−0.0092 (6)	0.0050 (6)	0.0013 (6)
O2	0.0253 (7)	0.0243 (7)	0.0182 (6)	0.0079 (6)	0.0035 (6)	0.0023 (5)
O3	0.0183 (6)	0.0262 (7)	0.0186 (6)	0.0023 (5)	0.0076 (5)	0.0000 (5)
C1	0.0139 (8)	0.0131 (8)	0.0136 (7)	−0.0012 (6)	0.0068 (6)	0.0010 (6)
C2	0.0179 (8)	0.0155 (8)	0.0124 (8)	−0.0014 (6)	0.0072 (7)	−0.0007 (6)
C3	0.0168 (8)	0.0190 (9)	0.0104 (8)	−0.0015 (6)	0.0042 (7)	0.0033 (6)
C4	0.0177 (8)	0.0173 (8)	0.0177 (8)	0.0023 (6)	0.0060 (7)	0.0072 (7)
C5	0.0214 (8)	0.0118 (8)	0.0206 (8)	0.0005 (7)	0.0090 (7)	0.0019 (7)
C6	0.0172 (8)	0.0120 (8)	0.0192 (8)	−0.0036 (6)	0.0069 (7)	−0.0013 (6)
C7	0.0183 (8)	0.0183 (8)	0.0147 (7)	0.0002 (7)	0.0039 (7)	0.0024 (7)
C8	0.0158 (8)	0.0130 (8)	0.0173 (8)	0.0008 (6)	0.0078 (6)	−0.0010 (6)
C9	0.0141 (8)	0.0148 (8)	0.0137 (7)	−0.0009 (6)	0.0015 (6)	0.0027 (6)

Geometric parameters (Å, º)

Cr1—C9	1.8484 (18)	C1—C2	1.412 (2)
Cr1—C8	1.8507 (18)	C1—C6	1.429 (2)
Cr1—C7	1.8549 (19)	C1—C1^i	1.493 (3)
Cr1—C3	2.2070 (18)	C2—C3	1.419 (3)
Cr1—C5	2.2137 (18)	C2—H2	0.9500
Cr1—C6	2.2150 (17)	C3—C4	1.401 (3)
Cr1—C2	2.2201 (17)	C3—H3	0.9500
Cr1—C4	2.2207 (18)	C4—C5	1.420 (3)
Cr1—C1	2.2384 (17)	C4—H4	0.9500
O1—C7	1.150 (2)	C5—C6	1.404 (2)
O2—C8	1.151 (2)	C5—H5	0.9500
O3—C9	1.152 (2)	C6—H6	0.9500
C9—Cr1—C8	87.62 (7)	C6—C1—C1^i	120.7 (2)
C9—Cr1—C7	89.69 (8)	C2—C1—Cr1	70.83 (10)
C8—Cr1—C7	88.76 (8)	C6—C1—Cr1	70.40 (10)
C9—Cr1—C3	121.50 (8)	C1^i—C1—Cr1	129.30 (16)
C8—Cr1—C3	150.61 (7)	C1—C2—C3	121.03 (16)
C7—Cr1—C3	87.61 (7)	C1—C2—Cr1	72.24 (10)
C9—Cr1—C5	87.79 (7)	C3—C2—Cr1	70.80 (10)
C8—Cr1—C5	123.22 (7)	C1—C2—H2	119.5
C7—Cr1—C5	147.74 (7)	C3—C2—H2	119.5
C3—Cr1—C5	66.72 (7)	Cr1—C2—H2	130.1
C9—Cr1—C6	111.22 (7)	C4—C3—C2	120.48 (17)
C8—Cr1—C6	94.73 (7)	C4—C3—Cr1	72.09 (10)
C7—Cr1—C6	158.89 (7)	C2—C3—Cr1	71.81 (10)
C3—Cr1—C6	79.15 (7)	C4—C3—H3	119.8
C5—Cr1—C6	36.98 (6)	C2—C3—H3	119.8
C9—Cr1—C2	158.42 (7)	Cr1—C3—H3	128.6
C8—Cr1—C2	113.84 (7)	C3—C4—C5	119.05 (16)
C7—Cr1—C2	92.89 (7)	C3—C4—Cr1	71.03 (10)
C3—Cr1—C2	37.38 (7)	C5—C4—Cr1	71.06 (10)
C5—Cr1—C2	78.66 (7)	C3—C4—H4	120.5
C6—Cr1—C2	66.65 (6)	C5—C4—H4	120.5
C9—Cr1—C4	92.17 (7)	Cr1—C4—H4	129.8
C8—Cr1—C4	160.51 (7)	C6—C5—C4	120.70 (16)
C7—Cr1—C4	110.73 (7)	C6—C5—Cr1	71.56 (10)
C3—Cr1—C4	36.88 (7)	C4—C5—Cr1	71.59 (10)
C5—Cr1—C4	37.35 (7)	C6—C5—H5	119.6
C6—Cr1—C4	67.20 (7)	C4—C5—H5	119.6
C2—Cr1—C4	66.90 (7)	Cr1—C5—H5	129.7
C9—Cr1—C1	148.25 (7)	C5—C6—C1	120.63 (16)
C8—Cr1—C1	90.27 (7)	C5—C6—Cr1	71.46 (10)
C7—Cr1—C1	121.94 (7)	C1—C6—Cr1	72.18 (10)
C3—Cr1—C1	67.34 (7)	C5—C6—H6	119.7
C5—Cr1—C1	67.13 (6)	C1—C6—H6	119.7
C6—Cr1—C1	37.42 (6)	Cr1—C6—H6	129.1
C2—Cr1—C1	36.94 (6)	O1—C7—Cr1	179.53 (18)
C4—Cr1—C1	79.71 (6)	O2—C8—Cr1	178.63 (16)
C2—C1—C6	118.10 (15)	O3—C9—Cr1	178.49 (16)
C2—C1—C1^i	121.24 (19)
C9—Cr1—C1—C2	−142.31 (14)	C1—Cr1—C3—C2	28.33 (10)
C8—Cr1—C1—C2	131.78 (11)	C2—C3—C4—C5	−0.9 (3)
C7—Cr1—C1—C2	43.07 (13)	Cr1—C3—C4—C5	54.30 (15)
C3—Cr1—C1—C2	−28.66 (10)	C2—C3—C4—Cr1	−55.19 (15)
C5—Cr1—C1—C2	−101.87 (11)	C9—Cr1—C4—C3	−145.14 (12)
C6—Cr1—C1—C2	−130.77 (15)	C8—Cr1—C4—C3	125.9 (2)
C4—Cr1—C1—C2	−65.03 (11)	C7—Cr1—C4—C3	−54.65 (12)
C9—Cr1—C1—C6	−11.54 (19)	C5—Cr1—C4—C3	131.36 (16)
C8—Cr1—C1—C6	−97.44 (11)	C6—Cr1—C4—C3	102.71 (12)
C7—Cr1—C1—C6	173.85 (11)	C2—Cr1—C4—C3	29.45 (10)
C3—Cr1—C1—C6	102.12 (11)	C1—Cr1—C4—C3	65.77 (11)
C5—Cr1—C1—C6	28.90 (10)	C9—Cr1—C4—C5	83.50 (11)
C2—Cr1—C1—C6	130.77 (15)	C8—Cr1—C4—C5	−5.5 (3)
C4—Cr1—C1—C6	65.74 (11)	C7—Cr1—C4—C5	173.99 (11)
C9—Cr1—C1—C1^i	102.5 (2)	C3—Cr1—C4—C5	−131.36 (16)
C8—Cr1—C1—C1^i	16.6 (2)	C6—Cr1—C4—C5	−28.65 (10)
C7—Cr1—C1—C1^i	−72.1 (2)	C2—Cr1—C4—C5	−101.91 (11)
C3—Cr1—C1—C1^i	−143.8 (2)	C1—Cr1—C4—C5	−65.59 (11)
C5—Cr1—C1—C1^i	143.0 (2)	C3—C4—C5—C6	−0.1 (3)
C6—Cr1—C1—C1^i	114.1 (3)	Cr1—C4—C5—C6	54.17 (15)
C2—Cr1—C1—C1^i	−115.1 (2)	C3—C4—C5—Cr1	−54.28 (15)
C4—Cr1—C1—C1^i	179.8 (2)	C9—Cr1—C5—C6	130.80 (11)
C6—C1—C2—C3	−0.5 (3)	C8—Cr1—C5—C6	45.10 (13)
C1^i—C1—C2—C3	178.43 (19)	C7—Cr1—C5—C6	−143.28 (14)
Cr1—C1—C2—C3	53.44 (15)	C3—Cr1—C5—C6	−103.34 (12)
C6—C1—C2—Cr1	−53.97 (14)	C2—Cr1—C5—C6	−66.08 (11)
C1^i—C1—C2—Cr1	125.0 (2)	C4—Cr1—C5—C6	−132.71 (16)
C9—Cr1—C2—C1	119.0 (2)	C1—Cr1—C5—C6	−29.23 (10)
C8—Cr1—C2—C1	−54.61 (12)	C9—Cr1—C5—C4	−96.49 (11)
C7—Cr1—C2—C1	−144.53 (11)	C8—Cr1—C5—C4	177.81 (10)
C3—Cr1—C2—C1	133.21 (15)	C7—Cr1—C5—C4	−10.57 (19)
C5—Cr1—C2—C1	66.87 (10)	C3—Cr1—C5—C4	29.37 (11)
C6—Cr1—C2—C1	30.08 (10)	C6—Cr1—C5—C4	132.71 (16)
C4—Cr1—C2—C1	104.13 (11)	C2—Cr1—C5—C4	66.63 (11)
C9—Cr1—C2—C3	−14.2 (2)	C1—Cr1—C5—C4	103.48 (12)
C8—Cr1—C2—C3	172.18 (11)	C4—C5—C6—C1	0.8 (3)
C7—Cr1—C2—C3	82.25 (11)	Cr1—C5—C6—C1	54.99 (15)
C5—Cr1—C2—C3	−66.34 (11)	C4—C5—C6—Cr1	−54.18 (15)
C6—Cr1—C2—C3	−103.13 (11)	C2—C1—C6—C5	−0.5 (3)
C4—Cr1—C2—C3	−29.08 (10)	C1^i—C1—C6—C5	−179.43 (19)
C1—Cr1—C2—C3	−133.21 (15)	Cr1—C1—C6—C5	−54.65 (15)
C1—C2—C3—C4	1.2 (3)	C2—C1—C6—Cr1	54.18 (14)
Cr1—C2—C3—C4	55.32 (15)	C1^i—C1—C6—Cr1	−124.8 (2)
C1—C2—C3—Cr1	−54.09 (15)	C9—Cr1—C6—C5	−54.24 (12)
C9—Cr1—C3—C4	42.05 (14)	C8—Cr1—C6—C5	−143.52 (11)
C8—Cr1—C3—C4	−146.56 (15)	C7—Cr1—C6—C5	117.6 (2)
C7—Cr1—C3—C4	130.23 (12)	C3—Cr1—C6—C5	65.52 (11)
C5—Cr1—C3—C4	−29.72 (10)	C2—Cr1—C6—C5	102.53 (12)
C6—Cr1—C3—C4	−66.30 (11)	C4—Cr1—C6—C5	28.92 (11)
C2—Cr1—C3—C4	−131.86 (16)	C1—Cr1—C6—C5	132.25 (16)
C1—Cr1—C3—C4	−103.53 (12)	C9—Cr1—C6—C1	173.52 (11)
C9—Cr1—C3—C2	173.91 (10)	C8—Cr1—C6—C1	84.24 (11)
C8—Cr1—C3—C2	−14.7 (2)	C7—Cr1—C6—C1	−14.6 (2)
C7—Cr1—C3—C2	−97.91 (11)	C3—Cr1—C6—C1	−66.73 (11)
C5—Cr1—C3—C2	102.14 (11)	C5—Cr1—C6—C1	−132.25 (16)
C6—Cr1—C3—C2	65.56 (11)	C2—Cr1—C6—C1	−29.71 (10)
C4—Cr1—C3—C2	131.86 (16)	C4—Cr1—C6—C1	−103.32 (12)

Symmetry code: (i) −x+1, −y, −z.