magnesium in tetrahydrofuran byproducts: MgBrCl; Sonication; the mixt. of magnesium, germane and halogen-compound in THF was sonicated for 2 h (inert atm.); the mixt. was washed with satd. soln. of NaCl, extd. with diethyl ether,the organic layer was dried over MgSO4, the solvent was removed under r educed pressure, column chromy. (petroleum ether-diethyl ether 95/5);