Borasilylenes in Focus: Topological Effects of Nitrogen Atoms by DFT

DFT calculations in combination with appropriate isodesmic reactions are employed to assess topological effects of nitrogens on thermodynamic parameters of novel mono-, di-, tri-, tetra-, and pentaaza-7-boratricyclo[1,1,1,0^1,7,0^7,3,0^7,5]hexa-2-silylenes (1–20). Despite the enormous steric strain involved in their cubic structures, all our scrutinized singlet and triplet silylenes (1_s-20_s vs. 1_t-20_t, respectively) appear as minima on their energy surfaces, for showing singlet ground states. The highest stability (ΔE_s−t) is achieved by 1,3,5-triaza-7-boratricyclo[1,1,1,0^1,7,0^7,3,0^7,5]hexa-2-silylene (11), where all the three nitrogens are bonded to the central boron atom. All of our silylenes show the same trend for their calculated ΔΕ_s−t and band gap (ΔΕ_HOMO−LUMO). Isodesmic reactions are employed to compare and contrast nucleophilicity (N), electrophilicity (ω), and heat of hydrogenation (ΔE_H) for our 40 silylenes (1_s-20_s vs. 1_t-20_t). In fact, we introduce a novel generation of tridimensional silylenes which have the intrinsic potential of expanding the existing boundaries of semiconductors, cumulated multi-dentate ligands, etc. [Figure not available: see fulltext.].