Decacarbonyldihydridotriosmium is an organoosmium compound with the formula H<sub>2</sub>Os<sub>3</sub>(CO)<sub>10</sub>. This purple-violet crystalline air-stable cluster is noteworthy because it is electron-deficient and hence adds a variety of substrates.
The trinuclear cluster features an isosceles triangular array of metals with one short edge (r<sub>Os-Os</sub> = 2.68 à), which is spanned by the two hydride ligands, and two longer edges (r<sub>Os-Os</sub> = 2.81 à). It can be described as Os(CO)<sub>4</sub>[Os(CO)<sub>3</sub>(ü-H)]<sub>2</sub>. The bonding in the Os<sub>2</sub>H<sub>2</sub> subunit has been compared to the 3-center, 2e bonding in diborane. The molecule forms a variety of adducts with loss of H<sub>2</sub>.
It is prepared by purging a solution of Os<sub>3</sub>(CO)<sub>12</sub> in octane (or other inert solvent of similar boiling point) with H<sub>2</sub>.
The cluster reacts with a wide range of reagents under mild conditions. Illustrative is its reaction with diazomethane to give Os<sub>3</sub>(CO)<sub>10</sub>(ü-H)(ü-CH<sub>3</sub>), exhibiting an agostic interaction, the first identified in a metal cluster.