Structures and Bonding of η2-Bridging CO Ligands and Their Influence on the Structures and Rearrangements of Higher Nuclearity Metal Carbonyl Cluster Complexes

Abstract

Three products were obtained from the reaction of IrRu3(CO)13(μ3-H) with P(But)3 in a hexane solution at reflux for 30 min. These have been identified as IrRu3(CO)12[P(But)3](μ-H) (1; 15% yield), IrRu2(CO)9[P(But)3](μ-H) (2; 29% yield), and IrRu3(CO)10(μ3-η2-CO)[P(But)3]2(μ-H) (3; 19% yield). Compound 1 is simply a P(But)3 derivative of IrRu3(CO)13(μ3-H). Compound 2 is electronically unsaturated and has a vacant coordination site located on the iridium atom. Compound 3 contains a butterfly tetrahedral cluster of four metal atoms with a rare η2 triply bridging CO ligand. Compound 3 reacts with Ru(CO)5 to yield the higher nuclearity cluster complex IrRu4(CO)12(μ4-η2-CO)[P(But)3]2(μ3-H) (4), which contains five metal atoms arranged in the form of an iridium-capped butterfly tetrahedron of four ruthenium atoms. Compound 4 contains a η2-quadruply bridging CO ligand. Compound 4 reacts with CO to yield the compound IrRu4(CO)14P(But)3(μ4-η2-CO)(μ-H), 5 which contains five metal atoms in the form of a spiked-tetra...