Mixed-metal cluster chemistry. 39. Syntheses and X-ray structures of Mo3Ir3(μ4-η2-CO)(μ3-CO)(CO)10(η5-C5H5)3 and Mo3RhIr3(μ-CO)4(CO)7(η5-C5H5)3(η5-C5Me5)

Abstract

Thermolysis of tetrahedral Mo2Ir2(μ-CO)3(CO)7(η5-C5H5)2 in refluxing toluene affords small amounts of Mo3Ir3(μ4-η2-CO)(μ3-CO)(CO)10(η5-C5H5)3 (1). Reaction of 1 with Rh(CO)2(η5-C5Me5) in refluxing dichloromethane gives Mo3RhIr3(μ-CO)4(CO)7(η5-C5H5)3(η5-C5Me5) (2) in moderate yield. X-ray diffraction studies show the metal cores adopt edge-bridged trigonal bipyramidal and bicapped trigonal bipyramidal structures, respectively. Cluster 2 is electron precise with 96 CVE, in contrast to the only precedent group 6-group 9 mixed-metal cluster with an identical core geometry, the 94 CVE W3Ir4(μ-H)(CO)12(η5-C5H5)3 (3). DFT studies have been employed to rationalize the contrasting behavior of 2 and 3. Time-dependent DFT has been employed to assign the key transitions in the linear optical absorption spectrum of 2.