One-electron redox reactions involving chromium(0) and molybdenum(0) bis-1,3,5-trimethylbenzene derivatives

The reaction of M(η⁶-1,3,5-Me₃C₆H₃)₂, M = Cr, Mo, with the tetrahalides of Groups 4 and 5 elements proceeds with the monoelectronic oxidation of the metal bis-arene to the [M(η⁶-Me₃C₆H₃)₂]⁺ cation. In the case of MX₄, M = Ti, X = Cl, Br, M = V, X = Cl, and of Nb₂Cl₁₀ the reduction products are the titanium(III), vanadium(III) halides and the niobium(IV) chloride, isolated as the solvate anions [MCl₄(THF)₂]⁻ and [NbCl₄(CH₃CN)]⁻. The reaction of the tetrachloro complexes MCl₄(THF)₂, M = Zr, Hf, with Cr(η⁶-1,3,5-Me₃C₆H₃)₂ in THF produces the ionic [Cr(η⁶-1,3,5-Me₃C₆H₃)₂][MCl₅(THF)], which has been characterized by single-crystal X-ray diffraction in the case of hafnium.