Addition von Silylenen an Iminoborane

Addition of Silylenes to Iminoboranes [1] Photolytically generated silylenes SiMe 2 and SiMes 2 are treated with iminoboranes XBN t Bu [X = t Bu, Me 3 Si( t Bu)N, i Pr 2 N: 1a–c ]. The products from SiMe 2 and 1a are the four‐and six‐membered rings [–B( t Bu)=N( t Bu)–SiMe 2 –SiMe 2 –] ( 3a ) and [–B( t Bu)N( t Bu)B( t Bu)N( t Bu)–SiMe 2 –SiMe 2 –] ( 4a ), depending on the conditions of the photolysis. SiMe 2 reacts with 1b to give the six‐membered ring [–BX=N( t Bu)–SiMe 2 –BX=N( t Bu)–SiMe 2 –] ( 4b ). From SiMes 2 and 1a,c the three‐membered rings [–BX=N( t Bu)–SiMes 2 –] are formed ( 2a : space group Pbca ; 2c : space group P1): SiMes 2 reacts with 1b to yield the unexpected four‐membered BNSiN ring [B(Mes)N( t Bu)–Si(Mes)(SiMe 3 )–N( t Bu)] ( 5 : space group P1).