Syntheses and structures of half-sandwich iridium(III) and rhodium(III) complexes with organochalcogen (S, Se) ligands bearing N-methylimidazole and their use as catalysts for norbornene polymerization.

The organochalcogen ligands derived from 3-methyl-imidazole-2-thione/selone groups, Mbit, Mbis, Ebit and Ebis [Mbit = 1,1'-methylenebis(3-methyl-imidazole-2-thione); Mbis = 1,1'-methylenebis(3-methyl-imidazole-2-selone), Ebit = 1,1'-(1,2-ethanediyl)bis(3-methyl-imidazole-2-thione), Ebis = 1,1'-(1,2-ethanediyl)bis(3-methyl-imidazole-2-selone)] have been synthesized and characterized. Reactions of [CpIr(micro-Cl)Cl]2 and [CpRh(micro-Cl)Cl]2 (Cp* = eta5-pentamethylcyclopentadienyl) with Mbit, Mbis, Ebit and Ebis result in the formation of the complexes [CpIr(Mbit)Cl]Cl 1a x Cl), [CpIr(Mbis)Cl]Cl (3a x Cl), [CpIr(Ebit)Cl]Cl (1b x Cl), [CpIr(Ebis)Cl]Cl (2a x Cl), [CpRh(Mbit)Cl]Cl (2b x Cl), CpRh(Mbis)Cl][CpRhCl(3)] (3b x[CpRhCl(3)]), [CpRh(Ebit)Cl]Cl (4a x Cl) and [CpRh(Ebis)Cl]Cl (4b x Cl), respectively. All compounds have been characterized by elemental analysis, NMR and IR spectra. The molecular structures of 1b, 2b, 3a, 3b and 4a have been determined by X-ray crystallography. After activation with methylaluminoxane (MAO), the iridium complexes exhibit moderate activities for the vinyl polymerization of norbornene.