Silver(i) complex of a new imino-N-heterocyclic carbene and ligand transfer to palladium(ii) and rhodium(i)

Abstract

A new imino-N-heterocyclic carbene ligand precursor [1-(2,4,6-Me₃C₆H₂)imidazolium-3-{CH₂C(t-Bu)N(i-Pr)}] bromide has been synthesised and structurally characterised. The silver(I) complex [Ag(C^⁁imine)₂]AgBr₂, where (C^⁁imine) = 1-(2,4,6-Me₃C₆H₂)imidazol-2-ylidene-3-{CH₂C(t-Bu)N(i-Pr)}, was readily prepared by reaction with Ag₂O. Transfer of the ligand from silver(I) to palladium(II) and rhodium(I) by reaction with [PdCl₂(MeCN)₂] and [Rh(cod)(THF)₂][BF₄] led to the tautomerisation of the imine moiety to the enamine affording the structurally characterised complex [PdCl₂(C^⁁enamine)] and [Rh(cod)(C^⁁enamine)][BF₄] respectively, where (C^⁁enamine) = 1-(2,4,6-Me₃C₆H₂)imidazol-2-ylidene-3-{CHC(t-Bu)NH(i-Pr)}.