Synthesis, Reactivities, and Catalytic Properties of Iodo-Bridged Polymeric Iridium Complexes with Flexible Carbon Chain-Bridged Bis(tetramethylcyclopentadienyl) Ligands

Dinuclear iridium complexes [(C5Me4)­(CH2)n­(C5Me4)]­[Ir­(COD)]2 (2a: n = 2; 2b: n = 3; 2c: n = 4) are obtained from the reactions of the corresponding dilithium salts Li2[(C5Me4)­(CH2)n­(C5Me4)] (n = 2–4) with [Ir­(μ-Cl)­(COD)]2. Further oxidation of 2 affords iodo-bridged polymeric iridium complexes [(C5Me4)­(CH2)n­(C5Me4)­(IrI2)2]m (3a: n = 2; 3b: n = 3; 3c: n = 4). Dinuclear iridium complexes [(C5Me4)­(CH2)n­(C5Me4)]­[IrI2(PPh3)]2 (4a: n = 2; 4b: n = 3; 4c: n = 4) and [(C5Me4)­(CH2)n­(C5Me4)]­[IrI2(CO)]2 (5b: n = 3; 5c: n = 4) are obtained from the reactions of 3 with PPh3 and CO, respectively. Dinuclear dicarbonyl iridium complexes [(C5Me4)­(CH2)n­(C5Me4)]­[Ir­(CO)2]2 (6b: n = 3; 6c: n = 4) are obtained from the reactions of 3 with Zn and CO. Additionally, the cyclometalated dinuclear iridium complexes 7b,c, 8b,c, 9b,c, and 10b,c are obtained from the reactions of 3 with the corresponding nitrogen ligands in the presence of KOH. The molecular structures of complexes 2a, 4a, 5b, 6c, and 7b have been determined by single-crystal X-ray diffraction analysis. Moreover, we found that complexes 3 and 4 are efficient catalysts for the selective amine cross-coupling reaction.