科研之友
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摘要
Two isomeric coronene-borazine hybrids C18B3N3H12, in which a central or outer C6-cycle is formally replaced by an alternating B3N3 cycle, are assessed for aromaticity on the ring-current criterion. Calculations for the B3LYP/6-31G** optimized structures (of D3h and Cs symmetry, respectively) at the coupled-Hartree-Fock ipsocentric level for treatment of magnetic response properties show distinct patterns of p-current: central substitution isolates a strongly diatropic C18 perimeter, whereas outer substitution leaves a phenanthrene-like circulation in the carbon-only region of the molecule. Circulations within the B3N3 moiety are limited to localized lone-pair circulations on the nitrogen centres. In the limit of the replacement strategy, where all C6 cycles are replaced, as in hexaborazino-coronene (B12N12H12, D3h), all p-currents become localized on nitrogen centers.
- 出版日期2013-2-1
