Application of Free-Wilson matrices to the analysis of the tautomerism and aromaticity of azapentalenes: a DFT study

The tautomerism and aromaticity of 44 neutral and the corresponding 60 protonated azapentalenes were studied. The tautomerism was based on the calculated relative energies of the different tautomers, from two to three and nine nitrogen atoms. The aromaticity was estimated from the NICS values of both rings of azapentalenes. The possible relationship between both properties was assessed. The calculation was carried out at the B3LYP/6-311++G^∗∗ computational level. MEP and NBO analysis were carried out on the studied compounds.