Superloading of Tin Ligands into Rhodium and Iridium Carbonyl Cluster Complexes

The reactions of Rh4(CO)12 and Ir4(CO)12 with Ph3SnH have yielded the new Rh−Sn and Ir−Sn cluster complexes M3(CO)6(μ-SnPh2)3(SnPh3)3, 1 (M = Rh) and 2 (M = Ir). Both compounds contain triangular M3 clusters with three bridging SnPh2 and three terminal SnPh3 ligands. The M−M bonds are unusually long. Molecular orbital calculations indicate that this is due to the importance of M−Sn bonding and weak direct M−M interactions. Reaction of 1 with Ph3SnH at reflux in 1,2-dichlorobenzene solvent yielded the complex Rh3(CO)3(SnPh3)3(μ-SnPh2)3(μ3-SnPh)2, 3, which contains eight tin ligands: three terminal SnPh3, three edge-bridging SnPh2, and two triply bridging SnPh ligands.