Studies on metal-acetylene complexes X. Spectroscopic studies of hexafluorobut-2-yne complexes, and the X-ray structure of an acetylene compound containing a chiral, chelating diphosphine

The acetylene complex ()-(N,N-bis(diphenylphosphino)-1-phenethylamine) (hexafluorobut-2-yne)platinum(O) has been prepared, and its structure determined by X-ray analysis. Crystals are monoclinic, space group P21, with a cell of dimensions a = 11.177(2), b = 15.690(3), c = 19.655(4) Å and β = 94.46(1)°. Intensity data collected on an automated four-circle diffractometer was used for full-matrix least-squares refinement on F, which converged at R = 0.059, 5851 observations. There are two molecules in the asymmetric unit. The coordination at the Pt atoms is essentially planar, and the CC bond distances are 1.26(2) and 1.25(2) Å. The deviations from linearity of the alkyne ligand upon coordination are 38(2)° and 46(2)° in one molecule, while values of 40(2)° and 39(2)° are found in the other. IR, 19F NMR and 31P NMR spectra are reported and discussed for this species and for the series of hexafluorobut-2-yne complexes of general formula ML2-(acetylene) which we have studied by X-ray techniques.