in benzene N2-atmosphere; slight excess of Fe-complex, 48 h; evapn. (room temp.), extn. into hexane, standing at -30°C for several d, removal of Fe3(CO)12 (-30°C), evapn. of filtrate, disssoln. in hexane, crystn. (-30°C, several weeks); elem. anal.;

(i), (ii) aq. HCl; Multistep reaction;