byproducts: LiC5Me4H; (Ar); course of react. invariant of react. conditions (including lowering temp. to -100°C);

in toluene byproducts: (CH3)2SnCl2; (N2); using Schlenk techniques; addn. of Me2Sn(C5Me4H-1)2 to ZrCl4 in toluene; stirring under reflux for 24 h; evapn.; addn. of hexane; filtration, concn.; cooling; crystn., elem. anal.;