Synthesis of Heterobimetallic Complexes by Coordination of Rhodium(III) and Iridium(III) Poly-N,O-NHC Complexes to Silver(I), Copper(II), and Zinc(II)

The reaction of [RhCl2(Cp*)](2) with 2-trimethylsiloxyphenyl isocyanide (1) led to the mononuclear diisocyanide complex [RhCl(Cp*)(1)(2)]. Cleavage of the Si-O bonds of the coordinated isocyanide ligands with a catalytic amount of KF and H2O gave the neutral rhodium(III) complex [RhCl(Cp*)(NH,O-NHC)(N,O-NHC)] ([2]) bearing a C2-metalated N,O-benzoxazolinato ligand and an NH,O-benzoxazolin-2-ylidene ligand. In the presence of AgBF4 the same reaction sequence with [MCl2(Cp*)](2) (M = Rh, Ir) and 1 led to the removal of all halogeno ligands and formation of the complexes [M(Cp*)(NH,O-NHC)(N,O-NHC)(2)] (M = Rh, [3]; M = Ir, [4]) bearing one C-metalated NH,O-NHC benzoxazolin-2-ylidene and two C-metalated N,O-benzoxazolinato ligands. Deprotonation of the remaining N-H function in complexes [3] and [4] generated complexes with three amido donor functions which act as tripodal metalloligands for the coordination to additional transition metals such as Ag-I, Cu-II, and Zn-II, thus allowing the preparation of the polynuclear heterobimetallic complexes [5]-[10] bearing C/N-metalated benzoxazolinato ligands.