Organo-silyl and -germyl complexes of platinum. Part II

Abstract

The reactions of trans-(Et₃P)₂Pt(X)MMe₃(M = Si, Ge and X = Cl, Ph, GePh₃) with HCl in ether and in benzene are described. A high degree of selectivity is observed and the reaction when M = Ge and X = GePh₃ provides a good synthetic route to trans-(Et₃P)₂Pt(Cl)GePh₃. The reversibility of the reaction of (Et₃P)₂Pt(Cl)GeMe₃ with hydrogen has been demonstrated and provides evidence for a hexaco-ordinate intermediate. The reactions of trans-(Et₃P)₂Pt(X)MMe₃(M = Si, Ge; X = Cl) with the diphosphine Ph₂P·CH₂·CH₂PPh₂ give ionic complexes [(Ph₂P·CH₂·CH₂·PPh₂)Pt(PEt₃)MMe₃]Cl. With hydrogen chloride in benzene, [(Ph₂P·CH₂·CH₂PPh₂)Pt(PEt₃)GeMe₃]Cl gives the isolable hexaco-ordinate complex [(Ph₂P·CH₂·CH₂·PPh₂)Pt(PEt_e)(H)(Cl)GeMe₃]Cl which decomposes in methanol to Me₃GeCl and the ionic platinum hydride [(Ph₂P·CH₂·CH₂·PPh₂)Pt(PEt₃)H]Cl; its decomposition in benzene is more complex. This platinum hydride is more readily prepared by the homogeneous hydrogenolysis of [(Ph₂P·CH₂·CH₂PPh₂)Pt(PEt₃)MMe₃]Cl, M = Si, Ge, in methanol. The ¹H n.m.r. and infrared spectra of some of the complexes are described and conductance data are reported. The salts are less rapidly hydrolysed than the neutral complexes and this is interpreted in terms of proton attack at platinum.