Studies on metal–acetylene complexes. VII. The molecular structure of bis(tricyclohexylphosphine)(hexafluorobut-2-yne)platinum(0)

Abstract

The acetylene complex Pt(P(cyclo-C6H11)3)2 (F3CC≡CCF3) crystallizes in the monoclinic space group P21/c with four formula units in a cell of dimensions a = 10.902(2),b = 21.766(3), c = 19.808(3) Å, and β = 116.52(1)°. Three-dimensional X-ray data were collected on a four circle automatic diffractometer using Cu radiation. The structure was solved by the heavy atom method, and refined by full-matrix least-squares methods on F. A conventional agreement factor of 0.062 was achieved, employing 6678 observations for which I > 0. The coordination geometry at the platinum atom is essentially planar, for the acetylene triple bond makes an angle of 6.5(5)° with the plane formed by the Pt and the two P atoms. The triple bond length is 1.260(10) Å. The acetylene adopts a cis-bent geometry, with a mean bend-back angle of 45.5(8)°. The ligand is considerably perturbed upon coordination to the Pt atom, as is evident from the Δv(C≡C) value of 578 cm−1.