High-Nuclearity Iridium Carbonyl Clusters Containing Phenylgermyl Ligands: Synthesis, Structures, and Reactivity

The reaction of Ir4(CO)12 with Ph3GeH at 97 °C has yielded the new tetrairidium cluster complexes Ir4(CO)7(GePh3)(μ-GePh2)2[μ3-η3-GePh(C6H4)](μ-H)2 (10) and Ir4(CO)8(GePh3)2(μ-GePh2)4 (11). The structure of 10 consists
of a tetrahedral Ir4 cluster with seven terminal CO groups, two bridging GePh2 ligands, an ortho-metallated bridging
μ3-η3-GePh(C6H4) group, a terminal GePh3 ligand, and two bridging hydrido ligands. Compound 11 consists of a
planar butterfly arrangement of four iridium atoms with four bridging GePh2 and two terminal GePh3 ligands. The
same reaction at 125 °C yielded the two new triiridium clusters Ir3(CO)5(GePh3)(μ-GePh2)3(μ3-GePh)(μ-H) (12)
and Ir3(CO)6(GePh3)3(μ-GePh2)3 (13). Compound 12 contains a triangular Ir3 cluster with three bridging GePh2,
one triply bridging GePh, and one terminal GePh3 ligand. The compound also contains a hydrido ligand that bridges
one of the Ir−Ge bonds. Compound 13 contains a triangular Ir3 cluster with three bridging GePh2 and three terminal
GePh3 ligands. At 151 °C, an additional complex, Ir4H4(CO)4(μ-GePh2)4(μ4-GePh)2 (14), was isolated. Compound
14 consists of an Ir4 square with four bridging GePh2, two quadruply bridging GePh groups, and four terminal
hydrido ligands. Compound 12 reacts with CO at 125 °C to give the compound Ir3(CO)6(μ-GePh2)3(μ3-GePh) (15).
Compound 15 is formed via the loss of the hydrido ligand and the terminal GePh3 ligand and the addition of one
carbonyl ligand to 12. All compounds were fully characterized by IR, NMR, single-crystal X-ray diffraction analysis,
and elemental analysis.