Dehydrogenation of LGeH by a Lewis N-heterocyclic carbene borane pair under the formation of L'Ge and its reactions with B(C(6)F(5))(3) and trimethylsilyl diazomethane: an unprecedented rearrangement of a diazocompound to an isonitrile.

Herein we report the dehydrogenation of LGeH (1) [L = CH{(CMe)(2,6-iPr(2)C(6)H(3)N)}(2)] by a frustrated Lewis NHC borane pair under the formation of an imidazolium borate salt (2) and the heterocyclic germylene L'Ge (3) [L' = CH{(C horizontal lineCH(2))(CMe)(2,6-iPr(2)C(6)H(3)N)(2)}]. The reaction of 3 with B(C(6)F(5))(3) in toluene results in the formation of a zwitterion containing a germylene moiety, [B(C(6)F(5))(3)L''Ge] (4) [L'' = CH{(CCH(2))(CMe)(2,6-iPr(2)C(6)H(3)N)(2)}]. Subsequent treatment of 4 with 1 equiv of 1,3-di-tert-butylimidazol-2-ylidene (NHC) gives B(C(6)F(5))(3)L'''Ge (5) [L''' = CH{(C horizontal lineCH(2))(CCH(2)B(C(6)F(5))(3))(2,6-iPr(2)C(6)H(3)N)(2)}] under formation of the imidazolium cation. Moreover compound 3 reacts with trimethylsilyl diazomethane (N(2)CHSiMe(3)) to form the diazogermylene LGeC(N(2))SiMe(3) (6) under C-H bond cleavage. Compound 6 slowly rearranges to the isonitriletrimethylsilyl germanium(II) amide LGeN(SiMe(3))NC (6a). All compounds were characterized by microanalysis and multinuclear NMR spectroscopy. Compounds 4, 6, and 6a were unequivocally identified by single crystal X-ray structure analysis.