Synthesis of metal-tetraazadiene complexes via Ar2N4, ligand transfer. Evidence for a stable tetraazadiene bridged intermediate

Abstract

Tetraazadiene ligands (Ar{2}N{4}, Ar = 4-MeC{6}H{4} or 3, 5-Me{2}C{6}H{3}) have been transferred under mild conditions from [Ni(Ar{2}N{4}){2}] to another nickel or platinum centre to yield [M(Ar{2}N{4})(t-BuNC){2}] complexes. No transfer was observed to a palladium centre, and neither was it observed to Ni or Pt in the presence of coligands other than t-BuNC. The reactions proceed via dinuclear intermediates of the type [Ni(Ar{2}N{4}){2}M(L){2}]. These complexes have aslo been isolated in cases when further transfer reactions did not take place (i.e. M = palladium or L = PEt{3}). One of the Ar{2}N{4} ligands in these dinuclear complexes is assumed to be bridging between nickel and M in a mode analogous to the @s-N, @s-N' bridge bonding mode found in platinum and palladium complexes of the 1,4-diaza-1,3-butadiene ligand.