in hexane A soln. of Ru(CO)5 is added dropwise to a refluxing soln. of Ru4(CO)12(CNMe2)(H) over a period of 3 h.; concn., chromy. on Florisil (hexane, hexane/CH2Cl2), further purification by TLC on silica gel (hexane, CH2Cl2); elem. anal.;