Electrochemical reactions of dichlorobis(aryl isocyanide)platinum(II) complexes

Abstract

Electrochemical reduction of cis-[PtCl₂(RNC)₂][(1a), R = 2,4-Bu^t₂-6-Me₆H₂; (1c), R = 2,4,6-Bu^t₃C₆H₂] 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.