in chloroform byproducts: C6H5I; a soln. of IBr is added dropwise with vigorous stirring to a soln. of Sn-compd. at room temp., after decolourisation the mixt. is refluxed for 2 h (N2); mixt. is concd. by distn. at reduced pressure (10 mmHg), to residue petroleum ether is added, kept at 0°C, ppt. is sepd. after 24 h, washed (petroleum ether) and dried at 20°C/10 mmHg, elem. anal.;