:OsO4 + 4 H2 → Os (s) + 4 H2OOsO4 undergoes "reductive carbonylation" with carbon monoxide in methanol at 400 K and 200 bar of pressure to produce the triangular cluster Os3(CO)12::3 OsO4 + 24 CO → Os3(CO)12 + 12 CO2====Oxofluorides====Osmium forms several oxofluorides, all of which are very sensitive to moisture.
Using primary amine tert-BuNH2 one obtains the corresponding imido derivative:: OsO4 + 4 (Me3CNH2 → Os(NCMe3)4 + 4 H2OOsO4 undergoes «reductive carbonylation» in methanol at 400 K and 200 bar of pressure to produce the triangular cluster Os3(CO)12:: 3 OsO4 + 24 CO → Os3(CO)12 + 12 CO2In this reaction osmium changes oxidation state by eight units.