Bimetallic osmium-tin complexes: Stannylene and hydrostannylene clusters upon addition of Ph_3SnH to unsaturated triosmium clusters [(μ-H)_2Os_3(CO)_8(μ-diphosphine)] (diphosphine = dppm, dppf)

摘要

Products of the addition of Ph3SnH to the unsaturated triosmium clusters [(μ-H)_2Os_3 (CO)_8(μ-dppm)] (1) and [(μ-H)_2Os_3(CO)_8(μ-dppf)] (2) are highly dependent on the nature of the diphosphine. With the rigid bis(diphenylphosphino)methane (dppm), the stannylene complex [H_2Os_3(CO)_7(μ-SnPh_2)_2(μ-dppm)] (3) is the major cluster product (35% yield), resulting from both Sn-H and Sn-C bond activation, while two previously reported triphenyltin complexes, [(μ-H)_2Os_3(CO)_8(SnPh_3)_2(μ-dppm)] (4) (10% yield) and [(μ-H)_2Os_3(CO)_8(SnPh_3){μ-Ph_2PCH_2P(Ph)C_6H_4}] (5) (11% yield) also result. Biphenyl is also a co-product of this reaction and it is postulated to be formed concomitantly with 3. A similar reaction with the highly flexible 1,1'-bis(diphenylphosphino)ferrocene (dppf) complex leads to the formation of four tin-containing complexes: two previously reported compounds [HOs(CO)_4(SnPh_3)] (6) (8% yield) and [Os_2(CO)_6(SnPh_3)_2(μ-SnPh_2)_2] (8) (5% yield), and the new triphenyltin and hydrostannylene clusters [H(μ-H)_2Os_3(CO)_8(SnPh_3)(μ-dppf)] (10) (22% yield) and [(μ-H)Os_2(CO)_4(SnPh_3)_2(μ-HSnPh_2)(μ-dppf)] (9) (12% yield) respectively, together with the dihydroxy cluster [Os_3(CO)_8(μ-OH)_2(μ-dppf)] (7). Two of these new clusters have been characterized by X-ray crystallography. Cluster 3 consists of a central Os_3 triangle with two stannylene groups, each bridging one Os-Os edge, a dppm ligand that bridges the third Os-Os edge, and two terminal hydride ligands. Cluster 10 consists of an Os_3 triangle with a terminal SnPh_3 group, one terminal and two bridging hydride ligands, and a bridging dppf ligand. The new compounds 3, 7, 9, and 10 have been investigated by electronic structure calculations, and the computed groundstate structures are discussed relative to the X-ray crystallographic structures.