Substituent Effect On Structure, Stability, and Electronic Properties of the Novel Bicyclic Silylenes at DFT

Abstract

The density functional theory (DFT) calculations are carried out to assay the effects of nitrogen atoms on the stability and reactivity of singlet (s) and triplet (t) forms of novel silylenes with one, two, and three silylene centers (1s-18s and 1t-18t, receptively) at B3LYP/6-311 + + G** level of theory. Every one of the 36 silylenes scrutinized appears as minimum on its energy surface, for showing no negative force constant. All of our silylenes have singlets ground state and the highest stability belongs to silylene 2 (ΔEs−t = 44.71.95 kcal/mol). This clearly demonstrates the effect of intermolecular interactions ( $$\sigma$$ (C(E and G)−H(exo))→LP*Si). The aim of the present work was to consider the influence of nitrogen substituents on the stability (ΔEs−t), band gap (ΔEHOMO−LUMO), nucleophilicity (N), electrophilicity (ω), and isodesmic reactions. Finally, our investigation offers new insights into the chemistry of novel bicyclic silylenes that can be applied as cumulated multi-dentate ligands. We have compared and contrasted the substituent effects on the stability and reactivity of singlet (s) and triplet (t) forms of novel silylenes with one, two, and three silylene centers (1s-18s and 1t-18t, receptively) at B3LYP/6-311 + + G** level of theory. All novel silylenes show singlet ground state and the highest stability belongs to silylene 2 (ΔEs−t = 44.71.95 kcal/mol). This stability can be related to its intermolecular interactions. The nonbonding electrons at the nitrogens (E or G) of silylenes 3s, 5s, 6s, 7s, 8s, 9s, 11s, 14s and 15s appear to have a tendency to interact with the empty p orbital of the silylene center and form a σ-bond.