Striking Reactivity of a Stable, Zwitterionic Silylene Towards Substituted Diazomethanes, Azides, and Isocyanides

The reactivity of the zwitter-ionic N-heterocyclic silylene (NHS) LSi: 1 (L=Ar-N-C(Me)=CH-C(=CH2)-N-Ar, Ar=2,6-iPr(2)C(6)H(3)), towards diphenyldiazomethane (Ph2CN2), trimethylsilyl azide (Me3SiN3) and cyclohexyl isocyanide (C6H11-NC) is reported. The addition of Ph2CN2 to 1 leads to the diiminylsilane LSi(N=CPh2)(2) 2 (80% yield), whereas the treatment of I with Me3SiN3 gives the spirobicyclic silatetrazoline LSi(NNSiMe3)(2) 3 (67% yield), and addition of C6H11-NC gives the silyl cyanide LSi(R)CN (R=cyclohexyl) 4 (32% yield) along with the unexpected azasilacyclobutane 5 (41 % yield). The novel compounds were fully characterized by H-1, C-13, and Si-29 NMR spectroscopy, ESIMS, elemental analysis, and single-crystal X-ray diffraction.