-Cleavage of Phenyl Groups from GePh3 Ligands in Iridium Carbonyl Cluster Complexes. A Mechanism and Its Role in the Synthesis of Bridging Germylene Ligands
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abstract
At 110 C, the compound HIr(CO) 3(GePh 3) 2 (1) was decarbonylated and transformed into five polynuclear iridium compounds, Ir 2(CO) 6(-GePh 2) (GePh 3) 2 (2), Ir 3(CO) 6( 1-Ph) 2(-GePh 2) 3(GePh 3) (3), Ir 3(CO) 6( 1-Ph)(- GePh 2) 3(GePh 3) 2 (4), Ir 3(CO) 6(-CO)(-GePh 2) 2(GePh 3) 3 (5), and Ir 3(CO) 6( 1-Ph)(-GePh 2) 2(GePh 3) 2[-Ge(Ph)(OH)] (6), by a combination of condensation and phenyl-cleavage processes. The triiridium compounds 3-6 are all new and have been characterized by single-crystal X-ray diffraction analyses. Each new compound consists of a closed triangular cluster of three iridium atoms with two or three diphenylgermylene ligands bridging the Ir-Ir bonds. Separately, compound 5 was converted to 4 in 68% yield by decarbonylation and cleavage of a phenyl group from one of its GePh 3 ligands by heating a toluene solution to reflux (110 C) for 1 h. A computational study has revealed that the mechanism of transformation of 5 to 4 occurs by elimination of the bridging carbonyl ligand followed by a "deinsertion" -cleavage of a phenyl group from one of the GePh 3 ligands. 2011 American Chemical Society.