Decacarbonyldihydridotriosmium Explained

Decacarbonyldihydridotriosmium is an organoosmium compound with the formula H₂Os₃(CO)₁₀. This purple-violet crystalline air-stable cluster is noteworthy because it is electron-deficient and hence adds a variety of substrates.

Structure and synthesis

The trinuclear cluster features an isosceles triangular array of metals with one short edge (r_Os-Os = 2.68 Å), which is spanned by the two hydride ligands, and two longer edges (r_Os-Os = 2.81 Å).^[1] It can be described as Os(CO)₄[Os(CO)₃(μ-H)]₂. The bonding in the Os₂H₂ subunit has been compared to the 3-center, 2e bonding in diborane. The molecule forms a variety of adducts with loss of H₂.^[2]

It is prepared by purging a solution of Os₃(CO)₁₂ in octane (or other inert solvent of similar boiling point) with H₂.^[3]

Os₃(CO)₁₂ + H₂ → Os₃H₂(CO)₁₀ + 2 CO

Reactions

The cluster reacts with a wide range of reagents under mild conditions. Illustrative is its reaction with diazomethane to give Os₃(CO)₁₀(μ-H)(μ-CH₃), exhibiting an agostic interaction, the first identified in a metal cluster.^{[4] [5]}

References

1. Melvyn Rowen Churchill . Frederick J. Hollander . John P. Hutchinson . Structural studies on polynuclear osmium carbonyl hydrides. 5.Crystal structure and molecular geometry of di-μ-hydrido-decacarbonyltriosmium, (μ-H)₂Os₃(CO)₁₀ . 1977 . . 28 . 11. 2697–2700 . 10.1021/ic50177a006.
2. Keister, J. B.; Shapley, J. R. "Solution Structures and Dynamics of complexes of Decacarbonyldihydrotriosmium with Lewis Bases" Inorganic Chemistry 1982, volume 21, pages 3304–3310; .
3. Kaesz, H. D. . Decacarbonyldi-μ-Hydridotriosmium: Os₃(μ-H)₂(CO)₁₀ . 1990 . 28 . 238–39. 10.1002/9780470132593.ch60 . Inorganic Syntheses.
4. 10.1021/ja00457a077. Activation of Hydrocarbons by Unsaturated metal Cluster Complexes. 6. Synthesis and Characterization of Methyldecacarbonylhydridotriosmium, Methylenedecacarbonyldihydridotriosmium, and Methylidynenonacarbonyltrihydridotriosmium. Interconversion of Cluster-Bound Methyl and Methylene Ligands . 1977 . Calvert . R. Bruce . Shapley . John R. . Journal of the American Chemical Society . 99 . 15 . 5225–5226 .
5. 10.1021/ja00492a047. Decacarbonyl(methyl)hydrotriosmium: NMR Evidence for a Carbon^...Hydrogen^...Osmium Interaction . 1978 . Calvert . R. Bruce . Shapley . John R. . Journal of the American Chemical Society . 100 . 24 . 7726–7727 .