Metallocenoids of platinum: Syntheses and structures of triangular triplatinum sandwich complexes of cycloheptatrienyl

Abstract

A series of bis-cycloheptatrienyl triangular triplatinum complexes are synthesized as a novel class of organoplatinum sandwich compounds. The tris-ethylene triplatinum sandwich complex and the monophenyl bis-ethylene sandwich complex of triangular triplatinum are structurally characterized by X-ray crystallographic analyses. The net assembling of three Pt⁰ atoms between two tropylium cations is initiated by complexation of a Pt⁰ moiety by a tropylium ligand, where the mononuclear cycloheptatrienyl Pt^II intermediate is detectable in situ by NMR. It is revealed that the choice of added ligands is crucial to the efficient formation as well as conversion of the key mononuclear cycloheptatrienyl Pt^II intermediate.