Trimethylphophinecobalt(I) complexes: crystal and molecular structure of [Co(CO) 2(PMe 3) 3]BPh 4

Abstract

Crystals of dicarbonyltris)trimethylphophine)cobalt(I) tetraphenylborate belong to the monoclinic space group P2 1/ c with a 10.135(4), b 12.630(4), c 29.35(1) Å, β 106.11(3)° and Z = 4. The structure was refined on 2969 nonzero Cu-K α reflections to R = 0.043. The unit-cell contains discrete BPh 4 − anions and [Co(CO) 2(PMe 3) 3 + cations. The coordination geometry of the cation lies roughly halfway between a trigonal bipyramid (with equatorial CO ligands) and a square pyramid (with trans basal CO ligands), defining an intermediate configuration along the interconversion pathway in the Berry process. The Co-P distance (2.246 Å) to the unique PMe 3 ligand (apical in the square pyramid or equatorial in the trigonal bipyramid) is longer than the other two (2.209 and 2.211 Å). The CoCO bond lenghts are 1.740 and 1.766 Å. the v(CO) infrared bands indicate that the same geometry is retained in CH 2Cl 2 and acetone.