in tetrahydrofuran (Ar); (CH3)2Zn (6.1 mmol) added to soln. of W compd. (0.51 mmol) at -78°C; soln. allowed to warm to ambient temp. and stirred for 10 h; soln. evapd. (vac.); CH2Cl2 added; filtration (Celite); EtOH added to the filtrate; ppt. filtered and washed sequentially (EtOH, diethyl ether,petroleum ether) to give microcrystals; elem. anal.;