in toluene N2 atmosphere; addn. of soln. of (Me2BS)2 to soln. of N(BBr2)3 (room temp., stirring), heating (60°C, 12 h); removal of volatiles (vac.), washing (pentane, 0°C), sublimation (1.3 Pa, 80°C); elem. anal.;

in pentane N2 atmosphere; addn. of soln. of (Me2BS)2 to soln. of N(BBr2)3 (molar ratio 1:1., dropwise, -78°C, stirring), warming to room temp. (16 h); removal of solvent, distn. (1.33 Pa, 80°C);