Structure and properties of B 2 N 2 C 14 isomers containing C2 bridge: a DFT study

The influence of insertion of C2 bridge between the two B-N bonds (-NBNB- [compound A], -NBBN- [compound B] and -BNNB- [compound C]) of B2N2C14 isomers on their electronic structures, aromaticity, reactivity and UV-Vis spectra have been investigated. DFT (density functional theory) calculation results at the level of ωB97XD/def2-TZVP indicate that all of the involved B2N2C14 isomers are anti-aromatic before and after the insertion of C2 bridge. Compared to the B2N2C14 isomers which contains -NBBN- unit, C2 bridge can blue-shift the λmax of compound A 125.9 nm, and slightly red-shift the λmax of compound B (3.0 nm) and compound C (9.7 nm). Among the three compounds, compound A has the strongest nucleophilicity, while electrophilicity of compound C is the strongest, and the reactive sites are located at B-C bonds and C-C bond (the C atoms here are all C atoms of C2 bridge). All of compound A, B and C can be used as adsorbent, especially for adsorbing polar molecules.