in acetone under Ar to soln. bis(((dimethylsilyl)methyl)diphenylstannyl)methane in acetone at 0°C was added soln. HgCl2 in acetone and stirred at room temp. for 14 h; soln. was filtered, solvent was removed in vacuo, residue was suspended in hot hexane, soln. was filtered, filtrate was kept overnight at 5°C; elem. anal.;