CO in octane byproducts: benzene; Irradiation (UV/VIS); heating to 160°C under 3000 psi CO for 6 h; the solvent was collected by distn. in vac. and photolyzed for 2 h at room temp. to give Os3(CO)12; residue was chromd. on silica gel (hexane/CH2Cl2); recrystn. from hexane;