Homo- and Heterodinuclear Head-to-Head or Head-to-Tail Complexes of Rhodium(I) and Iridium(1) with C-2,N-3 or C-8,N-9 Bridging Azolato Ligands

摘要

Reaction of in situ lithiated N-methylimidazole or 1,5,6-trimethylbenzimidazole with [M(cod)(mu-Cl)](2) (M = Rh, Ir) led to the exclusive formation of the homodinuclear head-to-head complexes [2]-[5], where the metal centers are bridged by two C,N-coordinated azolato ligands. The two metal centers are each coordinated by one cod ligand and either two carbon or two nitrogen donors of the azolato ligands. Access to a heterodinuclear Ir/Rh complex [6] was achieved via the lithiated iridium complex [7] and addition of an equimolar amount of [Rh(cod)(mu-Cl)](2). Deprotonation of caffeine with lithium diisopropylamide and addition of [M(cod)(mu-Cl)](2) (M = Rh, Ir) led to mixtures of the head-to-head (M = Ir: [8(H-H)]; M = Rh: [9(H-H)]) and head-to-tail isomers (M = Ir: [8(H-T)]; M = Rh: [9(H-T)]) of the homodinuclear complexes. The molecular structures of the homo- and heterodinuclear complexes [3], [5].2C(6)H(5)F, [6].2C(6)H(5)F, and [9(H-T)].C4H8O have been determined by X-ray diffraction studies.