Reactions of the unsaturated triosmium cluster [(μ-H)Os 3(CO) 8(Ph 2PCH 2P(Ph)C 6H 4)] with HX (X = Cl, Br, F, CF 3CO 2,CH 3CO 2): X-ray structures of [(μ-H)Os 3(CO) 7(η 1-Cl)(μ-Cl) 2(μ-dppm)],[(μ-H) 2Os 3(CO) 8(Ph 2PCH 2P(Ph)C 6H 4)] +[CF 3O] − and the two isomers of [(μ-H)Os 3(CO) 8(μ-Cl)(μ-dppm)

Abstract

Treatment of the electronically unsaturated cluster [(μ-H)Os 3(CO) 8(Ph 2PCH 2P(Ph)C 6H 4)] ( 1) with HCl gas at ambient temperature in dichloromethane afforded (μ-H)Os 3(CO) 8(μ-Cl)(μ-dppm) ( 2) and [(μ-H)Os 3(CO) 7(η 1-Cl)(μ-Cl) 2(μ-dppm)] ( 3). Thermolysis of 2 at 110 °C led to an isomer of 2, 4. A similar reaction of 1 with HBr gas gave [(μ-H)Os 3(CO) 8(μ-Br)(μ-dppm)] ( 5) as the only product which does not isomerize at 110 °C. In sharp contrast, treatment of 1 with HF gas gave the protonated species [(μ-H) 2Os 3(CO) 8(Ph 2PCH 2P(Ph)C 6H 4)] + ( 6). Treatment of 1 with CF 3CO 2H also gave cation 6 whereas CH 3CO 2H yielded [(μ-H)Os 3(CO) 8(μ-η 2-CH 3CO 2)(μ-dppm)] ( 7). Structures of 2, 3, 4 and 6 were established crystallographically. In 2, both the chloride and the hydride ligands simultaneously bridge the same Os–Os edge and the dppm spans another Os–Os bond whereas in 4, all the three ligands bridge the same Os–Os edge. Compound 3 is comprised of an open Os 3 arrangement in which one chloride bridges the open Os⋯Os edge, another chloride and a hydride mutually bridge an Os–Os bond and the third chloride is terminally coordinated to one of the Os atoms of the dppm bridged edge. The cation 6 consists of a triangle of osmium atoms in which the shortest Os–Os edge is bridged by a hydride and the metallated phenyl ring and the longest edge is bridged by another hydride and the diphosphine ligand.