The catalytic activity of trinuclear osmium clusters (mu-H)(2)Os-3(CO)
(10), (mu-H)Os-3(CO)(10)(mu-OH), (mu-H)Os-3(CO)(9)(PPh(3))(mu-OH), (mu
-H)Os-3(CO)(10){mu-O=CNHC(CH3)CO(2)Bu-t)}, and Os-3(CO)(12) is studied
in alkene oxidation reactions. Oxidants were oxygen donors, such as H
2O2, tert-BuOOH, and N-methylmorpholine N-oxide. Osmium clusters are f
ound to catalyze syn-hydroxylation at low temperatures and the oxidati
ve destruction of alkenes at room temperature. Osmium tetroxide is an
active catalytic species, which is formed by the destruction of cluste
rs in the oxidative medium.