in dichloromethane inert atmosphere; -78°C, then warming to room temp., stirring (8 h); volatiles removal (vac.), sublimation (80°C, 0.05 Torr); elem. anal.;

in pentane; benzene byproducts: ZnCl2; N2, Zn-compound added to a soln. of TaCl5 at room temp.; filtered, fractional recrystd. (hexane/toluene or pentane/benzene);