Synthesis, structural characterization and reactivities of hexaosmium carbonyl clusters with six-membered cyclic thioether and thioxane ligands

Abstract

Cluster complexes [Os 6(CO) 15{S(CH 2) 4CH 2} {μ-S(CH 2) 4CH 2}] 1 and [Os 5(CO) 15{S(CH 2) 4CH 2}] 2 were isolated from the reaction of [Os 6(CO) 16(MeCN) 2] with S(CH 2) 4CH 2 (L 1) in 24 and 22% yields respectively. Cluster degradation from 1 to 2 can be achieved by addition of a stoichiometric quantity of L 1 in CHCl 3 under reflux. Monosubstituted cluster complex [Os 6(CO) 16{μ-S(CH 2) 3SCH 2}] 3 containing a S(CH 2) 3SCH 2 (L 2) ligand bridging across an Os-Os edge via one of the sulfur atoms was isolated in good yield from a similar reaction. However, similar reaction between [Os 6(CO) 16(MeCN) 2] and S(CH 2) 2SCH 2CH 2 (L 3) gave [Os 6(CO) 16{S(CH 2) 2SCH 2CH 2} 2] 4 as the major product instead. The two thio ligands are found to co-ordinate in terminal fashion to two different vertices of the Os 6 core. Interaction of tridentate sulfur donor ligand SCH 2SCH 2SCH 2 (L 4) with [Os 6(CO) 16(MeCN) 2] afforded [Os 6(CO) 14-(μ-CO)(SCH 2SCH 2SCH 2)] 5 in which the ligand L 4 was found to cap over a triangular face of the Os 6 skeleton. Treatment of mixed-donor ligand S(CH 2) 2OCH 2CH 2 (L 5) yielded a pair of isomeric complexes [Os 6(CO) 15-{(S(CH 2) 2OCH 2CH 2} {μ-S(CH 2) 2OCH 2CH 2}] 6 and [Os 6(CO) 15{O(CH 2) 2SCH 2CH 2) {μ-S(CH 2) 2OCH 2CH 2}] 7. Carboxylation of 6 gave [Os 6(CO) 16{μ-S(CH 2) 2OCH 2CH 2}] 8 and [Os 6(CO) 18]. Hydrogenation of 6 led to the formation of dihydrido cluster [Os 6(CQ) 15(μ-H) 2{S(CH 2) 2OCH 2CH 2} {μ-S(CH 2) 2OCH 2CH 2}] 9. The metal skeleton of 9 can be described as two fused tetrahedra sharing a common edge. All new compounds were fully characterized by spectroscopic and analytical techniques. In addition the structures of 1, 2, 3, 4, 5, 6, 8 and 9 were established by X-ray crystallography.