Electrochemical reactions of dichlorobis(aryl isocyanide)platinum(II) complexes
Abstract
Electrochemical reduction of cis-[PtCl2(RNC)2][(1a), R = 2,4-But2-6-Me6H2; (1c), R = 2,4,6-But3C6H2] produced [Pt2Cl2(RNC)4](2) or [Pt3(RNC)6](4), depending on the charge consumed and reduction potential. Potentiostatic reduction of [PtCl2(2,6-Me2C6H3NC)2](1b) gave [Hg{Pt3(2,6-Me2C6H3NC)6}2](3b)via a two-electron transfer process. [Pt2Cl2(RNC)4](2) was formed by the chemical reaction of cis-[Pt2Cl2(RNC)2] with zero-valent complexes (3) or (4) which were obtained by the above electrochemical process. The structure of compound (2) consists of two perpendicular PtCl(RNC)2 planes joined by a Pt–Pt bond; extended Hückel molecular orbital calculations on [Pt2Cl2(HNC)4] indicate that the perpendicular geometry is more stable than the planar one. Reaction of binuclear complexes (2) with isocyanide in the presence of [NH4][PF6] or NaClO4 gave [Pt2(RNC)6][X]2(8)(X = PF6 or ClO4). In the electronic spectra of the binuclear complexes (2) and (8) the absorption near 320 nm is assigned to a σ–σ* excitation.