sodium ethoxide in benzene (N2); organic ligand, sodium ethoxide added in benzene to a Schlenk flask; stirred for 10 min; tri-n-butyltin chloride added to mixt. (in 1:1:1 molar ratio); stirred for 12 h at 40°C; filtered; filtrate gradually evapd.; recrystallized from ether-petroleum; elem. anal.;