Reactivity of the Unsaturated Triosmium Cluster Os3(CO)8(μ3-η2-Ph2PCH2P(Ph)C6H4)(μ-H) with Benzothiophene: Activation of a P−C Bond in Diphosphine and a C−H Bond in Benzothiophene

Treatment of the electronically unsaturated cluster Os 3 (CO) 8 (μ 3 -η 2 -Ph 2 PCH 2 P(Ph)C 6 H 4 )(μ-H) ( 1 ) with benzothiophene in refluxing m -xylene afforded Os 3 (CO) 7 (μ-PPh 2 )(μ-PMePh)(μ 3 -η 2 -C 6 H 4 ) ( 2 ), Os 3 (CO) 7 (μ 3 -η 2 -PPh(C 6 H 4 )CH 2 PPh)(μ 3 -η 3 -SC 8 H 5 )(μ-H) ( 3 ), and Os 3 (CO) 8 (μ-CO)(μ 3 -η 2 -PPh(C 6 H 4 )CH 2 PPh) ( 4 ). Thermolysis of 1 in refluxing toluene for 35 h afforded only 4, whereas in refluxing m -xylene it gave both 4 and 2 . Compound 4 can also be obtained from the thermolysis of Os 3 (CO) 9 (μ 3 -η 2 -PPh(C 6 H 4 )CH 2 PPh 2 )(μ-H) ( 5 ) in refluxing toluene. All the complexes have been structurally characterized. Compound 3 contains a unique example of a μ 3 -η 2 benzothienyl ligand coordinated through the sulfur atom and the C−C double bond of the five-membered ring in a σ,π vinyl fashion. This coordination mode results in the rupture of one osmium−osmium bond, whereas the basic triangular metal framework is retained in the case of 2 and 4, which are derived from the activation of P−C and C−H bonds of 1 and do not contain any benzothiophene-derived ligand.