Bis(μ-di­phenyl­phosphan­yl)bis­[(tri­methyl­phosphane)cobalt(I)](Co—Co)

Robert Beck; Hans-Friedrich Klein

doi:10.1107/S1600536813027384

. 2013 Oct 16;69(Pt 11):m604. doi: 10.1107/S1600536813027384

Bis(μ-diphenylphosphanyl)bis[(trimethylphosphane)cobalt(I)](Co—Co)

Robert Beck ^a,^*, Hans-Friedrich Klein ^a

PMCID: PMC3884259 PMID: 24454035

Abstract

The title compound, [Co₂{P(C₆H₅)₂}₂(C₃H₉P)₄], was obtained by the addition of diphenylphosphane to a solution of Co(CH₃)(C₃H₉P)₄. The dinuclear complex molecule exhibits inversion symmetry with the inversion centre located between the two Co^I atoms. The short Co—Co distance of 2.3670 (8) Å lies within the range of metal–metal double bonds. As a result of inversion symmetry, the four-membered Co₂P₂ core is rigorously planar, and the two bridging P(C₆H₅)₂-ligands and the terminal C₃H₉P ligands are arranged in a pseudo-tetrahedral fashion about the Co^I atom.

Related literature

For related homobimetallic cobalt complexes, see: Harley et al. (1983 ▶); Jones et al. (1983 ▶); Winterhalter et al. (2001 ▶): For related salt metathesis reactions, see: Klein et al. (1988 ▶, 2003 ▶); Klein & Karsch (1975 ▶). graphic file with name e-69-0m604-scheme1.jpg

Experimental

Crystal data

[Co₂(C₁₂H₁₀P)₂(C₃H₉P)₄]
M _r = 792.49
Monoclinic,
a = 10.318 (2) Å
b = 19.262 (4) Å
c = 10.721 (2) Å
β = 113.32 (3)°
V = 1956.8 (7) Å³
Z = 2
Mo Kα radiation
μ = 1.12 mm⁻¹
T = 173 K
0.12 × 0.10 × 0.08 mm

Data collection

Bruker APEX CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2003 ▶) T _min = 0.912, T _max = 0.940
37952 measured reflections
5413 independent reflections
3251 reflections with I > 2σ(I)
R _int = 0.062

Refinement

R[F ² > 2σ(F ²)] = 0.037
wR(F ²) = 0.083
S = 0.81
5413 reflections
205 parameters
H-atom parameters constrained
Δρ_max = 0.45 e Å⁻³
Δρ_min = −0.86 e Å⁻³

Data collection: SMART (Bruker, 2001 ▶); cell refinement: SAINT (Bruker, 2001 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012 ▶); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I. DOI: 10.1107/S1600536813027384/wm2765sup1.cif

e-69-0m604-sup1.cif^{(18.2KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813027384/wm2765Isup2.hkl

e-69-0m604-Isup2.hkl^{(265.1KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

Financial support of this work by the Fonds der Chemischen Industrie is gratefully acknowledged.

supplementary crystallographic information

1. Comment

The synthesis of bimetallic complexes with bridging anionic PR₂ ligands (R = aryl or alkyl) are long time established (Harley et al., 1983), and numerous variants of synthetic approaches were developed (Jones et al., 1983). During the course of our investigations into the chemistry of cyclometallation of triphenylphosphane derivatives (Winterhalter et al., 2001), we isolated, structurally and spectroscopically characterized a series of ortho-metallated cobalt complexes (Klein et al., 2003). Using previous method allowed to synthesize a related bimetallic cobalt complex via salt metathesis of CoCl(PMe₃)₃ with LiPPMe₂ in high yield (Klein et al., 1988).

The molecular structure of the bimetallic title complex, (I), [Co(C₃H₉P)₂(µ₂-P(C₆H₅)₂)]₂, is shown in Fig. 1. The complex exhibits a crystallographically imposed inversion centre in the middle of the molecule. Each Co^I atom has a distorted tetrahedral coordination geometry with a short Co—Co distance of 2.3670 (8) Å, slightly longer than found for other Co═Co distances of homobimetallic cobalt complexes. Each set of terminal ligands is trans with respect to the Co═Co bond. Both bridging µ₂-PPh₂ and PMe₃-ligands are bent away from the central Co₂P₂ core with the distortion from idealized tetrahedral geometry being greater for the larger PPh₂ group with 115.13 (3)°.

The crystal packing of compound (I) can be described as being composed of rods of single molecules stacked along [100] and [001], with the Co₂P₂ cores arranged in alternating directions (Fig. 2).

2. Experimental

Standard vacuum techniques were used in manipulations of volatile and air sensitive material. Literature methods were applied for the preparation of Co(CH₃)(PMe₃)₄ (Klein & Karsch, 1975). Other chemicals were used as purchased. The title compound bis(µ₂-diphenylphosphino)tetrakis(trimethylphosphane) dicobalt(I) was synthesized by combining stoichiometric amounts of diphenylphosphane (118 mg, 0.63 mmol) in 20 ml of n-pentane at 203 K with a sample of Co(CH₃)(PMe₃)₄ (240 mg, 0.63 mmol) in 20 ml of n-pentane, effecting a change of color from red to dark brown. After warm-up, the mixture was kept stirring at 293 K for 16 h, and then the volatiles were removed in vacuo to give a dark brown, waxy solid. This was dissolved in a mixture of 10 ml of n-pentane / diethyl ether (3:1) and crystallized at 253 K to give brown rhombic crystals, which were suitable for X-ray diffraction. Isolated yield 145 mg (58%); m. p. 391–393 K (dec.). ¹H NMR (300 MHz, THF-d₈, 293 K, p.p.m.): δ = 0.88 (s(br), 36H, PCH₃); 7.03 - 7.11 (m, 12H, Ar—H); 7.51 – 7.56 (m, 8H, Ar—H); - ³¹P{¹H} NMR (121 MHz, THF-d₈, 297 K, p.p.m.): δ = 4.66 (s(br), 4P, PCH₃), 12.3 (s(br), 2P, PPh₂). Anal. Calcd. for C₃₆H₅₆Co₂P₆ (792.5): C, 54.56; H, 7.12; P, 23.45: Found: C, 54.88; H, 6.72; P 23.98%.