Crystal and molecular structure of a platinum(0) complex of cyclooctyne

Abstract

The crystal and molecular structure of a platinum(0) complex of cyclooctyne, [(coct)Pt(PPh₃)₂], has been determined from three- dimensional X-ray data collected by counter methods. The complex crystallizes in the space group P2₁/n [a non-standard setting of space group P2₁/c (C_2h⁵, No. 14)], with a 20.660(9), b 12.299(5), c 15.470(7) Ǻ, β 110.26(2)°, Z 4. The structure was solved by conventional Patterson and Fourier methods and was refined by block-diagonal least-squares techniques to weighted and unweighted R-factors of 0.048 and 0.047 respectively, for the 4733 unique reflections with I/σ(I) ≥ 3.0. The molecule is essentially square planar about the 'central' platinum atom, with the triphenylphosphine groups occupying cis coordination sites. The Pt-C distances are equal within experimental error [2.034(9) and 2.037(9) Ǻ] and compare favourably with the corresponding distances in the platinum(0)-cyclohexyne and -cycloheptyne analogues. The acetylenic C=C distance is 1.279(13) Ǻ and shows the normal bond lengthening consequent upon coordination.