New platinum hydrido acetylides. Crystal and molecular structure of [PtHC≡C-C(OH)MeEt(PPh3)2]

The complex trans-[PtClH(PPh3)2] reacts with monosubstituted acetylenes HC≡CR (R = CH2OH, CH(OH)Me, C(OH)Me2, C(OH)MeEt, CH(OH)Ph, C6H10OH, Ph, or CMe=CH2) in the presence of NEt2H to give trans-[PtH(C≡CR)(PPh3)2], which have been characterized by i.r., u.v., and n.m.r. spectroscopy. An X-ray diffraction analysis was carried out on [PtH{C≡C-C(OH) MeEt}(PPh3)2]. Crystals are monoclinic, space group P21/n, with unit cell dimensions a = 15.560(3), b = 26.696(5), c = 9.038(2) Å, β = 98.51(2)°, Z = 4. A total of 3 855 observed reflections have been measured by single-crystal diffractometry and refined by blocked full-matrix least squares to R = 0.067. Co-ordination around platinum is distorted square planar and involves the acetylide ligand trans to hydrogen which was directly located. In some reaction conditions cationic intermediates have been demonstrated by conductivity measurements.