Some four- and five-co-ordinate cations of platinum(II) containing alkylphosphine and hydride ligands
Abstract
Hydrogen-1 and 31P n.m.r. spectroscopy have been used to study the equilibrium of trans-[PtH(I)(PEt3)2] with an additional phosphine L [mol ratio 1 : 1, L = PMe3-nHn(n= 0–3) or PEt3] in CD2Cl2 solution. The spectra are temperature dependent and the cation [PtH(PEt3)2L]+ is observed at –90 °C. These cations (except L = PH3) have been isolated as [BPh4]– salts from reactions in methanol. A mixture of trans-[PtH(I)(PEt3)2] and PMeH2(mol ratio 1 : 2) gives completely reversible temperature-dependent n.m.r. spectra from which the formation of [PtH(PMeH2)2(PEt3)2]+ is inferred. Reaction of [PtH(PEt3)3]+ with PMeH2, PMe2H, or PMe3 at –90 °C in CD2Cl2 gives well resolved spectra of [PtH(PEt3)L3]+. The spectra show the five-co-ordinate cations to have a trigonal-bipyramidal structure with the PEt3 groups in equatorial positions.