A complete series of N-heterocyclic tetrylenes (Si–Pb) with a 1,1′-ferrocenediyl backbone enabled by 1,3,2-diazaborolyl N-substituents

Abstract

The use of bulky 1,3,2-diazaborolyl N-substituents has allowed the synthesis of the complete series of ferrocene-based N-heterocyclic tetrylenes fc[(N{B})₂E] (fc = 1,1′-ferrocenediyl, {B} = (HCNC₆H₃-2,6-ⁱPr₂)₂B, E = Si–Pb). The silylene fc[(N{B})₂Si] is inert towards NH₃, CO₂ or N₂O under ambient conditions and thus significantly less reactive than the N-aryl homologue fc[(NC₆H₃-2,6-ⁱPr₂)₂Si]. In accord with its higher reactivity, computational results indicate a more pronounced ambiphilicity of fc[(NC₆H₃-2,6-ⁱPr₂)₂Si]. Our computational investigation of the model compound fc[(NBMe₂)₂Si] suggests that silylenes of this type may be superior to fc[(NC₆H₃-2,6-ⁱPr₂)₂Si] in terms of ambiphilicity.