magnesium; ethylene dibromide in tetrahydrofuran byproducts: ethylene; Ar atmosphere; to a suspn. of Mg in THF was added 1,2-dibromoethane, after evolution of C2H4 mixt. was stirred for 5 min and GeMe3Cl was added followed by slow addn. of the ligand in THF maintaining the temp. close to 40°C, stirred at room temp.; the solvent was removed in vac., the residue extd. with hexane, the filtrate was washed with HCl, dried (Na2CO3) and concd., distn.; elem. anal.;