in n-heptane under N2, reflux for 22 h (98. degree.C); solvent was removed in vac., chromy. on silica, elution with hexane/CH2Cl2 (7:3, v/v), first band was Os3(CO)12, compd. from third band was recrystd. from hexane/CH2Cl2 at -20 °C, elem. anal.;

in dichloromethane under N2, Me3NO in CH2Cl2 was added dropwise to CH2Cl2 soln. of Os-complex (molar ratio was 2:1), stirring at room temp. for 20 h; solvent was removed in vac., chromy. on silica, elution with hexane/CH2Cl2 (7:3, v/v), recrystd. from hexane/CH2Cl2 at -20 °C;