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

Cluster complexes [Os-6(CO)(15){S(CH2)(4)CH2}{mu- S(CH2)(4)CH2}] 1 and [Os- 5(CO)(15){S(CH2)(4)CH2}] 2 were isolated from the reaction of [Os-6(CO)(16) (MeCN)(2)] with S(CH2)(4)CH2 (L-1) in 24 and 22% yields respectively. Clust er degradation from 1 to 2 can be achieved by addition of a stoichiometric quantity of L-1 in CHCl3 under reflux. Monosubstituted cluster complex [Os- 6(CO)(16){mu-S(CH2)(3)SCH2}] 3 containing a S(CH2)(3)SCH2 (L-2) ligand brid ging 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(CH2)(2)SCH2CH2 (L-3) gave [Os-6(CO)(16){S(CH2)(2)SCH2CH 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. I nteraction of tridentate sulfur donor ligand SCH2SCH2SCH2 (L-4) with [Os-6( CO)(16)(MeCN)(2)] afforded [Os-6(CO)(14)(mu-CO)(SCH2SCH2SCH2)] 5 in which t he ligand L-4 was found to cap over a triangular face of the Os-6 skeleton. Treatment of mixed-donor ligand S(CH2)(2)OCH2CH2 (L-5) yielded a pair of i someric complexes [Os-6(CO)(15){S(CH2)(2)OCH2CH2}{mu- S(CH2)(2)OCH2CH2}] 6 and [Os-6(CO)(15){O(CH2)(2)SCH2CH2}{mu- S(CH2)(2)OCH2CH2}] 7. Carboxylation of 6 gave [Os-6(CO)(16){mu-S(CH2)(2)OCH2CH2}] 8 and [Os-6(CO)(18)]. Hydrog enation of 6 led to the formation of dihydrido cluster [Os-6(CO)(15)(mu-H)( 2){S(CH2)(2)OCH2CH2}{mu- S(CH2)(2)OCH2CH2}] 9. The metal skeleton of 9 can be described as two fused tetrahedra sharing a common edge. All new compoun ds 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.