SOLID-GAS REACTIONS OF THE LIGHTLY STABILIZED OS-3(CO)(11)L(L=NCCH3, C2H4) CLUSTERS WITH CO, NH3, AND H-2

The solid-gas reactions of the ''lightly stabilized'' Os-3(CO)(11)L (L = NCCH3 (1), L = C2H4 (2)) clusters with gaseous reactants as CO, NH3, and H-2 have been investigated. At 80 degrees C polycrystalline samples (ca. 50 mg) of 1 and 2 undergo substitution of the axially bound acetonitrile ligand and the equatorially coordinated ethene ligand by the gaseous reactants. 1 and 2 react with (CO)-C-13 to form Os-3(CO)(11)((CO)-C-13) (3a), but no site selectivity is observed for the labeled carbonyl ligand (as shown by C-13 MAS NMR). On reaction with NH3 both 1 and 2 afford OS3(CO)(11)(NH3) (4) with the ammonia ligand coordinated in an axial position. The observed stereochemistry of the reaction products of 1 and 2 with CO and NH3 suggests the presence of an unsaturated intermediate Os-3(CO)(11), which displays an intramolecular axial-equatorial exchange of the vacant coordination site. Reaction with dihydrogen of solid OS3-(CO)(11)(NCCH3) (1) or Os-3(CO)(11)(C2H4) (2) gives H2Os3(CO)(11) as first product, which under the experimental conditions affords Os-3(CO)(12) and H2Os3(CO)(10).