The reaction of triphenylphosphine selenide with triosmium clusters: A facile cluster coupling through a selenium atom

Abstract

The room temperature reactions of Ph3PSe with the triosmium clusters Os3(CO)11(CH3CN), Os3(CO)10(CH3CN)2 and Os3(μ-H)2(CO)10 have been investigated. The reaction with an equimolar amount of Os3(CO)11(CH3CN) afforded the known clusters Os3(μ3-Se)2(CO)9, 1, and Os3(CO)11(PPh3), 2, and the new cluster Os3(μ3-Se)(CO)9(PPh3), 3. The analogous reaction with Os3(CO)10(CH3CN)2 gave 1 and 2; reaction with 0.5 equivalent of the cluster gave 1 quantitatively. The reaction with Os3(μ-H)2(CO)10 gave two new clusters, viz. Os3(μ3-Se)(μ-H)2(CO)8 (PPh3), 4a, and Os6(μ3-Se)(H)(μ-H)3 (CO)18(PPh3)2, 5a. Single crystal structures of 3, 4a and 5a have been obtained. Cluster 3 possesses bridging carbonyls; these appear to have been lost on elongation of the osmium-osmium bonds by bridging hydrides in 4a. The structure of 5a is novel and comprises a naked μ3-Se atom bridging two triosmium moieties; an Os3(μ-H)(CO)10 unit and an Os3(H)(μ-H)2(CO)8 (PPh3)2 unit.