Synthesis of chromium(0) and molybdenum(0) bis (η6-arene) derivatives and their monoelectronic oxidation to [M(η6-arene)2]+ cations

Abstract

M(η⁶-arene)₂ species (M = Cr, arene = 1,3,5-Me₃C₆H₃; M = Mo, arene = 1,3,5-Me₃C₆H₃, 1,3,5-ⁱPr₃C₆H₃), have been prepared by a modified Fischer–Hafner synthesis or by metal vapour techniques. The reaction of Cr(η⁶-1,3,5-Me₃C₆H₃)₂ with the fulvene derivatives pentacarbomethoxycyclopentadiene (pcmcpH), 1-benzoyl-6-hydroxy-6-phenylfulvene (dbcpH), or 1-benzoyl-3-nitro-6-hydroxy-6-phenylfulvene (dbncpH) proceeds with evolution of dihydrogen and formation of the ionic derivatives [Cr(η⁶-1,3,5-Me₃C₆H₃)₂][E], where E = pcmcp, dbcp, or dbncp. Mo(η⁶-arene)₂ derivatives (arene = toluene, 1,3,5-Me₃C₆H₃, 1,3,5-ⁱPr₃C₆H₃) are oxidized to [Mo(η⁶-arene)₂]⁺ by pcmcpH. The crystal and molecular structures of [M(η⁶-1,3,5-R₃C₆H₃)₂][pcmcp] (M = Cr, R = Me; M = Mo, R = Me, ⁱPr) have been solved by X-ray single crystal diffraction.