The application of Aj, BAC, I6, HOMA indexes for quantitative determination of aromaticity of metal complexes with benzoic, salicylic, nicotinic acids and benzene derivatives

The structural data from Cambridge structural database (CSD) were used to calculate the geometry-based aromaticity indexes (i.e. HOMA, BAC, Aj, I6) for metal benzoates, salicylates, nicotinates (46 compounds) and metal benzene derivatives (681 compounds). The perturbing or stabilising effect of metals on the π-electron system was studied. The obtained results were compared with our previous spectroscopic ones. The statistical analysis of the obtained results was performed. The application of the indexes for a quantitative measurement of aromaticity of the studied compounds was discussed. The values of the calculated indexes showed that among studied elements the following ones: Al, Cr, Mg, Ni and Zn stabilise the electronic charge distribution in benzene ring to the highest degree. The dependencies between the disturbance of the π-electron system and the distance between the central metal and the aromatic carbon atom, as well as ionic potential and atomic mass of metals were discussed.