HYDRIDOCYANOALKYL COMPLEXES OF PLATINUM(II) - INSERTION OF OLEFINS INTO THE PT-H BOND

The preparation and spectroscopic properties are described of some platinum(II) complexes having a hydride ligand cis or trans to an sp3 carbon, viz. trans-PtH(YCN)(PPh3)2 and cis-PtH(YCN)(LL) with YCN = C2H4CN, n-C3H6CN, o-CH2C6H4CN and LL = bis(diphenylphosphino)-ethene or -ethane. The complexes trans-PtH(YCN)(PPh3)2 can add a fifth ligand in solution; the resulting five-coordinate complex was observed by 31P NMR in the case of PtH(C3H6CN)(PPh3)3. Insertion of olefin (ethen, 1-cyanoethene, norbornadiene, allen) into the PtH bond of the trans-hydrido complexes occurs to give cis-dialkyl complexes, but the cis-hydrido complexes are unreactive. The mechanism of insertion is discussed in terms of the kinetics and the geometries of reactants and products. © 1979.