Aromaticity of benzenoid hydrocarbons with inserted -B=B- and -BH-BH- groups: A comparison

Structures of selected polycyclic conjugated hydrocarbons with -B=B- and -BH-BH- moieties inserted in different places were calculated at the B3LYP/6-311++Glevel and their aromatic properties evaluated. HOMA, NICS(0), NICS(1)zz, Λ and PDI indices were used for studying their aromatic properties. Both optimized planar (as in parent hydrocarbons) and non-planar structures were taken into account. It is shown that insertion of both types of boron groups disturbs and decreases the aromaticity of the corresponding hydrocarbons. The decreasing effect of the -BH-BH- group is much stronger. What is quite intriguing is that it appears that non-planar structures of the studied compounds have a little higher aromaticity than the strictly planar ones. Mutual correlations between results obtained by different aromaticity indices are calculated and thoroughly discussed.We thank the Ministerio de Ciencia e Innovación (Project No. CTQ2012-35513-C02-02) and the Comunidad Autónoma de Madrid (Project MADRISOLAR2, ref. S2009/PPQ-1533) for their continuing support. Thanks are also given to “ICM” Warsaw (Project Number G17-8) and to the CTI (CSIC) computer centers for an allocation of computer time.Peer Reviewe