ammonia T=-60°C; 6 h;

in toluene soln. of Me2Si(tBuN)2Sn added dropwise to a soln. of the silylamine in toluene, stirring for two hours, refluxing for one hour, volatile substances removed in vacuum and the seconocubane-like intermediate pyrolysed in vacuo at 0.01 Torr and 250°C; product sublimed, elem. anal.;