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

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-2ylidene-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-{CH=C(t-Bu)NH(i-Pr)}.