in benzene N2-atmosphere; 3 equiv. of ligand, 8-10°C, 1-2 days (to beginningof formation of tricarbonyl-complex); filtration, evapn. (below 5°C), dissoln. in cold Et2O, cooling to-80°C (crystn. of excess ligand), filtration, evapn. of filtrate , dissoln. in pentane (-20°C), crystn. (below 0°C); elem. anal.;

in benzene N2-atmosphere; equimolar amts., stirring (40°C, 8-10 h); filtration, evapn., recrystn. (CH2Cl2/hexane); elem. anal.;