Preparation and crystal structure of trans-carbonylhydridotris(triphenylphosphine)cobalt(I): a quantitative assessment of trigonal bipyramidal geometry

Abstract

trans-Carbonylhydridotris(triphenylphosphine)cobalt(I) has been prepared in 80% yield via carbonylation of [CoH₃(PPh₃)₃]. [Co(CO)H(PPh₃)₃] is monoclinic, space group P2₁/c, with four molecules per unit cell, dimensions a= 17.07(1), b= 11.41(1). c= 25.04(2)Å, β= 107.41(7)°. Its crystal structure has been refined by rigid-body full-matrix isotropic-anisotropic least squares on 1 900 independent counter data to a final R′ of 0.038 and R of 0.087. The molecule is a distorted trigonal bipyramid with the hydride and carbonyl ligands in axial positions. Bond lengths in the cobalt co-ordination sphere are: Co–H = 1.41(9). Co–C = 1.70(2), Co–P(av.)= 2.188(8)Å. A new quantitive measure of distortion from trigonal bipyramidal geometry is introduced : the half-open cone angle in [Co(CO)H(PPh₃)₃] is 81.6° and the exterior bond-cone axis angle is 1.5°.