Stepwise Formation of Tetra- and Hexanuclear Iridium and Rhodium Complexes Containing Oxalato Ligands

The reactions of [Cp*2Ir2(μ-η2-η2-C2O4)Cl2] 2a and [Cp*2Rh2(μ-η2-η2-C2O4)Cl2] 2b with bidentate ligands such as 4,4‘-bipyridine (bpy) and 2,5-bis(4-pyridyl)-1,3,5-oxadiazole (bpo) in the presence of AgOTf gave the corresponding tetranuclear complexes [Cp*4M4(μ-L)2(μ-η2-η2-C2O4)2](OTf)4 (3a: M = Ir, L = bpy; 3b: M = Rh, L = bpy; 4a: M = Ir, L = bpo; 4b: M = Rh, L = bpo). The reactions of 2a and 2b with tridentate ligand 2,4,6-tri(4-pyridyl)-1,3,5-triazine (tpt) in the presence of AgOTf gave the corresponding hexanuclear complexes [Cp*6M6(μ-tpt)2(μ-η2-η2-C2O4)3](OTf)6 (5a: M = Ir; 5b: M = Rh).