Syntheses, Reactivity Studies and the Catalytic Properties of a Series of Tetraosmium−Gold Mixed‐Metal Clusters

Treatment of the mixture of [Os 4 (μ‐H) 4 (CO) 12 ] and [AuPPh 3 Cl] with excess triethylamine afforded three novel tetraosmium−gold mixed‐metal clusters, [Os 4 Au 2 (μ‐H) 2 (CO) 11 (PPh 3 ) 3 ] ( 4 ), [Os 4 Au 3 (μ‐H) 3 (CO) 11 (PPh 3 ) 3 ] ( 5 ), and [Os 4 Au 4 (μ‐H) 2 (CO) 11 (PPh 3 ) 4 ] ( 6 ) in moderate yields. Cluster [Os 4 Au(μ‐H) 3 (CO) 11 (NMe 3 )(PPh 3 )] ( 2 ) was also obtained in a similar reaction in the presence of trimethylamine N ‐oxide. They were fully characterized by different spectroscopic techniques, and the solid‐state structures were established by X‐ray analysis. These dimetallic clusters exhibit an osmium/gold ratio ranging from 1 to 4. Their electronic absorption properties, electrochemistry, and catalytic properties, as a result of the oxidative carbonylation of aniline, were investigated in terms of the Os/Au ratio. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)