Oxidation State Assignments in the Organoplatinum One-Electron Redox Series [(N^N)PtMes2]n, n = +,0, –,2-

Abstract

The neutral complexes [(N^N)PtMes2], N^N = bis(1-methyl-2-imidazolyl)ketone (bik) or N,N'-disubstituted 1,2-bis-iminoacenaphthenes (R-BIAN), Mes = mesityl, were obtained and characterized as PtII species with planar N2PtC2 configuration and charge transfer transitions in the visible. Reversible one-electron reduction produces radical anion complexes with the spin predominantly localized in the N^N ligand, according to EPR, UV/Vis-IR spectroelectrochemistry, DFT and TD-DFT studies. Reversible one-electron oxidation was also possible, attributed to the steric and electronic influence from the mesityl ligands. The EPR silent cation [(bik)PtMes2]+ was characterized by UV/Vis-NIR spectroscopy and TD-DFT calculations as a system with spin density contributions from Pt (31 %) and two mesityl groups (69 %).