in neat (no solvent) heating for 3 h at 120-130°C; the mixt. was distd. in vac.; elem. anal.;

hydrogen bromide in dichloromethane to soln. of Sn compd. added slowly (2 h) soln. of 2.1 equiv of HBr at -78°C, slowly warmed to 25°C, reacted for 8-10 h; evapd. (vac.), chromd. (MeCN or MeCN/THF);