Carbene Complexes of Rhodium and Iridium from Tripodal N-Heterocyclic Carbene Ligands: Synthesis and Catalytic Properties

Two tripodal trisimidazolium ligand precursors have been tested in the synthesis of new N-heterocyclic carbene rhodium and iridium complexes. [Tris(3-methylbenzimidazolium-1-yl)]methane sulfate gave products with coordination of the decomposed precursor. [1,1,1-Tris(3-butylimidazolium-1-yl)methyl]ethane trichloride (TIMEH3Bu) coordinated to the metal in a chelate and bridged-chelate form, depending on the reaction conditions. The crystal structures of two of the products are described. The compounds resulting from the coordination with TIMEBu were tested in the catalytic hydrosilylation of terminal alkynes.