1: 2,2'-azobisisobutyronitrile / melt 2: chloroform View Scheme

in chloroform dropwise addn. of a soln. of Br2 in CHCl3 to a soln. of tin compd. in CHCl3 at 0°C, stirring for 24 h; evapn., recrystn. (hexane); elem. anal.;