in toluene N2; mixt. of Os complexes in toluene heated at 60°C for 66 h; the solvent removed in vac., the residue dissolved in CH2Cl2, chromy. silica gel; eluate C6H14/CH2Cl2 (1:4), third fraction collected, concd., cooled to -25°C to give crystals of product, elem. anal.;