Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270107049943/ga3072sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270107049943/ga3072Isup2.hkl |
CCDC reference: 672395
Crystals of (I) were obtained from a solution of 2,6-Mes2C6H3Sb(SbMe2)2 (Mes = 2,4,6-Me3C6H2) and [Cr(CO)4(nbd)] in a 1:1 molar ratio in benzene, in a sealed NMR tube at ambient temperature. The synthesis has not been reproduced in preparative scale.
During the space-group determination using XPREP (Bruker, 1998), the reflections -2,0,3; 0,0,3 and -2,0,1 were removed. The hydrogen atoms were placed in calculated positions (C—H = 0.98 Å) using a riding model with thermal parameters set at 1.5 times those of the carbon atoms directly attached, Uiso(H)=1.5Ueq(C). The methyl groups were allowed to rotate. The largest residual electron density is located 1.22 Å from the hydrogen atom H4C and the deepest hole is located at 0.88 Å from the antimony atom Sb1.
Data collection: Stoe IPDS1 (Stoe, 1999); cell refinement: Stoe IPDS1 (Stoe, 1999); data reduction: Stoe IPDS1 (Stoe, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg & Putz, 2006); software used to prepare material for publication: WinGX (Farrugia, 1999) and publCIF (Westrip, 2007).
[Cr2Sb4(CH3)8(CO)8] | F(000) = 872 |
Mr = 935.35 | Dx = 2.32 Mg m−3 |
Monoclinic, C2/m | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2y | Cell parameters from 4362 reflections |
a = 13.125 (3) Å | θ = 1.7–26.1° |
b = 11.332 (2) Å | µ = 4.80 mm−1 |
c = 10.185 (2) Å | T = 173 K |
β = 117.91 (3)° | Prism, orange |
V = 1338.6 (6) Å3 | 0.2 × 0.2 × 0.1 mm |
Z = 2 |
Stoe IPDS-1 diffractometer | 1367 independent reflections |
Radiation source: fine-focus sealed tube | 1173 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.036 |
ϕ scans | θmax = 26.0°, θmin = 2.3° |
Absorption correction: part of the refinement model (ΔF) (Walker & Stuart, 1983) | h = −16→16 |
Tmin = 0.447, Tmax = 0.646 | k = −13→13 |
4676 measured reflections | l = −12→12 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.024 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.056 | H-atom parameters constrained |
S = 0.99 | w = 1/[σ2(Fo2) + (0.0352P)2] where P = (Fo2 + 2Fc2)/3 |
1367 reflections | (Δ/σ)max = 0.001 |
78 parameters | Δρmax = 1.07 e Å−3 |
0 restraints | Δρmin = −0.55 e Å−3 |
[Cr2Sb4(CH3)8(CO)8] | V = 1338.6 (6) Å3 |
Mr = 935.35 | Z = 2 |
Monoclinic, C2/m | Mo Kα radiation |
a = 13.125 (3) Å | µ = 4.80 mm−1 |
b = 11.332 (2) Å | T = 173 K |
c = 10.185 (2) Å | 0.2 × 0.2 × 0.1 mm |
β = 117.91 (3)° |
Stoe IPDS-1 diffractometer | 1367 independent reflections |
Absorption correction: part of the refinement model (ΔF) (Walker & Stuart, 1983) | 1173 reflections with I > 2σ(I) |
Tmin = 0.447, Tmax = 0.646 | Rint = 0.036 |
4676 measured reflections |
R[F2 > 2σ(F2)] = 0.024 | 0 restraints |
wR(F2) = 0.056 | H-atom parameters constrained |
S = 0.99 | Δρmax = 1.07 e Å−3 |
1367 reflections | Δρmin = −0.55 e Å−3 |
78 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.6517 (5) | 0.5 | 0.9467 (6) | 0.0303 (12) | |
C2 | 0.8118 (4) | 0.6170 (5) | 0.9177 (5) | 0.0398 (11) | |
C3 | 0.7730 (5) | 0.5 | 0.6748 (7) | 0.0348 (13) | |
C4 | 0.6187 (5) | 0.8432 (4) | 0.6852 (6) | 0.0438 (11) | |
H4A | 0.6898 | 0.8505 | 0.7795 | 0.066* | |
H4B | 0.5596 | 0.8954 | 0.6863 | 0.066* | |
H4C | 0.634 | 0.8654 | 0.6031 | 0.066* | |
C5 | 0.4114 (4) | 0.6845 (4) | 0.6924 (6) | 0.0387 (10) | |
H5A | 0.437 | 0.6954 | 0.7987 | 0.058* | |
H5B | 0.3629 | 0.6138 | 0.6574 | 0.058* | |
H5C | 0.367 | 0.7536 | 0.6376 | 0.058* | |
Sb1 | 0.55915 (2) | 0.66384 (2) | 0.65639 (3) | 0.02674 (10) | |
Cr1 | 0.70963 (7) | 0.5 | 0.80719 (9) | 0.0272 (2) | |
O1 | 0.6229 (4) | 0.5 | 1.0357 (5) | 0.0463 (11) | |
O2 | 0.8752 (3) | 0.6908 (4) | 0.9881 (4) | 0.0592 (10) | |
O3 | 0.8167 (5) | 0.5 | 0.5997 (6) | 0.0500 (12) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.023 (3) | 0.030 (3) | 0.032 (3) | 0 | 0.009 (2) | 0 |
C2 | 0.034 (2) | 0.057 (3) | 0.032 (2) | −0.008 (2) | 0.0182 (19) | −0.003 (2) |
C3 | 0.035 (3) | 0.032 (3) | 0.035 (3) | 0 | 0.014 (3) | 0 |
C4 | 0.051 (3) | 0.029 (2) | 0.051 (3) | −0.008 (2) | 0.024 (2) | −0.005 (2) |
C5 | 0.037 (2) | 0.042 (3) | 0.045 (3) | 0.000 (2) | 0.025 (2) | −0.0007 (19) |
Sb1 | 0.02856 (15) | 0.02384 (14) | 0.02756 (15) | −0.00119 (12) | 0.01291 (11) | −0.00108 (10) |
Cr1 | 0.0252 (4) | 0.0311 (5) | 0.0246 (4) | 0 | 0.0111 (4) | 0 |
O1 | 0.047 (3) | 0.059 (3) | 0.040 (3) | 0 | 0.027 (2) | 0 |
O2 | 0.053 (2) | 0.077 (3) | 0.044 (2) | −0.034 (2) | 0.0202 (18) | −0.0204 (19) |
O3 | 0.061 (3) | 0.052 (3) | 0.055 (3) | 0 | 0.042 (3) | 0 |
C1—O1 | 1.134 (8) | C4—H4C | 0.98 |
C1—Cr1 | 1.900 (6) | C5—Sb1 | 2.148 (4) |
C2—O2 | 1.161 (6) | C5—H5A | 0.98 |
C2—Cr1 | 1.846 (5) | C5—H5B | 0.98 |
C3—O3 | 1.151 (8) | C5—H5C | 0.98 |
C3—Cr1 | 1.887 (7) | Sb1—Cr1 | 2.6205 (9) |
C4—Sb1 | 2.148 (4) | Sb1—Sb1i | 2.8157 (11) |
C4—H4A | 0.98 | Cr1—C2ii | 1.846 (5) |
C4—H4B | 0.98 | Cr1—Sb1ii | 2.6205 (9) |
O1—C1—Cr1 | 176.4 (5) | C4—Sb1—Sb1i | 97.32 (14) |
O2—C2—Cr1 | 179.1 (4) | C5—Sb1—Sb1i | 97.44 (14) |
O3—C3—Cr1 | 176.8 (6) | Cr1—Sb1—Sb1i | 121.89 (3) |
Sb1—C4—H4A | 109.5 | C2—Cr1—C2ii | 91.8 (3) |
Sb1—C4—H4B | 109.5 | C2—Cr1—C3 | 89.91 (19) |
H4A—C4—H4B | 109.5 | C2ii—Cr1—C3 | 89.91 (19) |
Sb1—C4—H4C | 109.5 | C2—Cr1—C1 | 88.55 (18) |
H4A—C4—H4C | 109.5 | C2ii—Cr1—C1 | 88.55 (18) |
H4B—C4—H4C | 109.5 | C3—Cr1—C1 | 177.8 (3) |
Sb1—C5—H5A | 109.5 | C2—Cr1—Sb1ii | 177.44 (14) |
Sb1—C5—H5B | 109.5 | C2ii—Cr1—Sb1ii | 88.94 (16) |
H5A—C5—H5B | 109.5 | C3—Cr1—Sb1ii | 92.55 (14) |
Sb1—C5—H5C | 109.5 | C1—Cr1—Sb1ii | 89.01 (12) |
H5A—C5—H5C | 109.5 | C2—Cr1—Sb1 | 88.94 (16) |
H5B—C5—H5C | 109.5 | C2ii—Cr1—Sb1 | 177.44 (14) |
C4—Sb1—C5 | 100.00 (19) | C3—Cr1—Sb1 | 92.55 (13) |
C4—Sb1—Cr1 | 117.64 (15) | C1—Cr1—Sb1 | 89.01 (12) |
C5—Sb1—Cr1 | 118.02 (13) | Sb1ii—Cr1—Sb1 | 90.23 (4) |
C4—Sb1—Cr1—C2 | 11.4 (2) | C4—Sb1—Cr1—C1 | 100.0 (2) |
C5—Sb1—Cr1—C2 | −108.7 (2) | C5—Sb1—Cr1—C1 | −20.08 (19) |
Sb1i—Sb1—Cr1—C2 | 131.09 (13) | Sb1i—Sb1—Cr1—C1 | −140.34 (12) |
C4—Sb1—Cr1—C3 | −78.5 (2) | C4—Sb1—Cr1—Sb1ii | −171.03 (16) |
C5—Sb1—Cr1—C3 | 161.5 (2) | C5—Sb1—Cr1—Sb1ii | 68.92 (15) |
Sb1i—Sb1—Cr1—C3 | 41.22 (14) | Sb1i—Sb1—Cr1—Sb1ii | −51.34 (4) |
Symmetry codes: (i) −x+1, y, −z+1; (ii) x, −y+1, z. |
Experimental details
Crystal data | |
Chemical formula | [Cr2Sb4(CH3)8(CO)8] |
Mr | 935.35 |
Crystal system, space group | Monoclinic, C2/m |
Temperature (K) | 173 |
a, b, c (Å) | 13.125 (3), 11.332 (2), 10.185 (2) |
β (°) | 117.91 (3) |
V (Å3) | 1338.6 (6) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 4.80 |
Crystal size (mm) | 0.2 × 0.2 × 0.1 |
Data collection | |
Diffractometer | Stoe IPDS1 diffractometer |
Absorption correction | Part of the refinement model (ΔF) (Walker & Stuart, 1983) |
Tmin, Tmax | 0.447, 0.646 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4676, 1367, 1173 |
Rint | 0.036 |
(sin θ/λ)max (Å−1) | 0.616 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.024, 0.056, 0.99 |
No. of reflections | 1367 |
No. of parameters | 78 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 1.07, −0.55 |
Computer programs: Stoe IPDS1 (Stoe, 1999), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), DIAMOND (Brandenburg & Putz, 2006), WinGX (Farrugia, 1999) and publCIF (Westrip, 2007).
C1—O1 | 1.134 (8) | C3—Cr1 | 1.887 (7) |
C1—Cr1 | 1.900 (6) | C4—Sb1 | 2.148 (4) |
C2—O2 | 1.161 (6) | C5—Sb1 | 2.148 (4) |
C2—Cr1 | 1.846 (5) | Sb1—Cr1 | 2.6205 (9) |
C3—O3 | 1.151 (8) | Sb1—Sb1i | 2.8157 (11) |
C4—Sb1—C5 | 100.00 (19) | Cr1—Sb1—Sb1i | 121.89 (3) |
C4—Sb1—Sb1i | 97.32 (14) | Sb1ii—Cr1—Sb1 | 90.23 (4) |
C5—Sb1—Sb1i | 97.44 (14) | ||
Sb1i—Sb1—Cr1—Sb1ii | −51.34 (4) |
Symmetry codes: (i) −x+1, y, −z+1; (ii) x, −y+1, z. |
Distibines act as donor ligands through the lone pairs of the antimony atoms to one or two transition metal complex fragments (Breunig & Fichtner, 1979, 1981; Breunig & Knobloch, 1980; von Seyerl & Huttner, 1980; Breunig et al., 1981, 2003; Bernal et al., 1984; Weber, Huttner et al., 1985; Weber, Zsolnai et al., 1985; Dickson et al., 1993; Breunig & Pawlik, 1995; Sharma et al., 1995; Balázs et al., 2003; Lorenz et al., 2005). From the reaction of [Cr(CO)4(nbd)] [nbd = norbornadiene (C7H8)] and tetramethyldistibine, a polymeric complex [Cr(CO)4(µ-Sb2Me4)]n with a trans arrangement of the distibine ligands was obtained (Breunig & Knobloch, 1980). We report here the structure of {[Cr(CO)4]2(µ-Sb2Me4)2} (I), the first complex featuring two bridging distibine ligands between transition metal complex fragments. (I) is a cyclic isomer of the polymer [Cr(CO)4(µ-Sb2Me4)]n (Breunig & Knobloch, 1980).
A thermal ellipsoid representation of the crystal structure of (I) is shown in Fig. 1. The centre of the molecule is located on a special position of 2/m symmetry. The Sb—Sb bond lengths in (I) are in the range of values found in the analogous complexes {[Cr(CO)5]2(µ-Sb2Me4)} [2.8097 (9) Å] (Breunig et al., 2003) and {[Cr(CO)5]2(µ-Sb2Ph4)} [2.865 (4) Å] (von Seyerl & Huttner, 1980). In addition, the Sb—Cr bond lengths are of the same magnitude as other reported values: 2.621 (8) and 2.629 (9) Å in {[Cr(CO)5]2(µ-Sb2Me4)} (Breunig et al., 2003) and 2.626 (1) Å in {[Cr(CO)5]2(µ-Sb2Ph4)} (von Seyerl & Huttner, 1980).
The geometries of the Cr(CO)4 fragments are normal, the bond angles being close to the ideal value of 90°. The C—Sb—Sb, C—Sb—C bond angles are larger than in the uncoordinated distibine Me4Sb2 [mean C—Sb—Sb 93.6 (6), mean C—Sb—C 93.5 (15)°] (Ashe et al., 1984), and are in the range of values found for the corresponding angles in {[Cr(CO)5]2(µ-Sb2Me4)} [C—Sb—Sb 96.41 (11)—102.44 (11); C—Sb—C 99.20 (18)–100.34 (16)°] (Breunig et al., 2003). The geometrical parameters of antimony are consistent with the known transition from being close to a p3 configuration to an sp3 hybridization of the coordinating atoms in pnicogen ligands by complexation.
The distibine fragments in (I) adopt a synclinal conformation, with a torsion angle Cr—Sb—Sb—Cr of 66.88 (4)° [cf. ideal antiperiplanar conformation with Cr—Sb—Sb—Cr 180° in {[Cr(CO)5]2(µ-Sb2Me4)} (Breunig et al., 2003) and {[Cr(CO)5]2(µ-Sb2tBu2Cl2)} (Weber, Zsolnai et al., 1985); anticlinal conformation with Cr—Sb—Sb—Cr 130.98 (36)° in {[Cr(CO)5]3(Sb2tBu2)} (Weber, Huttner et al., 1985)]. The antimony and chromium atoms form a six-membered heterocycle in a chair conformation. There are transannular contacts [3.7133 (9) Å] between the antimony atoms of the parallel distibine units shorter than the sum of the van der Waals radii [ΣrvdW(Sb,Sb) = 4.0 Å] (Bondi, 1964).
The crystals consist of stacks of molecules of (I), which are directed along the a axis, each stack being surrounded by six neighbouring stacks. There are contacts of 2.73 and 2.74 Å between the carbonyl oxygen atoms and the hydrogen atoms of the methyl groups of neighbouring molecules, both inside and between stacks.