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We examine the aromaticity of four benzoborepin isomers using magnetic, geometric, and delocalization criteria. We observe a trend in which the six-membered ring (6MR) exhibits higher aromaticity for isomers 1 and 2, while the seven-membered ring (7MR) exhibits a more pronounced aromatic character in isomers 3 and 4. Our CCSD(T)-level calculations demonstrate that isomers 1 and 2 are more stable (in that order), consistent with their higher aromaticity than isomers 3 and 4. The results of the three criteria mentioned above show a preference for forming the 6MR over the 7MR in the more stable isomers. Additionally, the 6MR in 1 shows a higher aromaticity when compared to 2 which explains its greater stability. For this reason, we conclude that the Glidewell–Lloyd rule governs aromaticity and relative stability in benzoborepines. [ABSTRACT FROM AUTHOR]

In this work, we have revisited the aromaticity of benzyne isomers at the unrestricted density functional theory level (UDFT) using the energetic, magnetic, and delocalization criteria. In addition, this last criterion has also been analyzed employing complete active space (CASSCF) calculations. The results show conservation of aromaticity in these monocycles. Additionally it is observed that this trend is maintained in polycyclic aromatic hydrocarbon derivatives such as biradical didehydrophenanthrenes. Do these results imply a violation of Baird's rule? The answer is No, because this conservation in aromaticity is due to the loss of hydrogen atoms affects only the electronic σ skeleton and exerts a minor influence on the π cloud. Additionally, we have analyzed the relative stability of benzyne isomers and their relationship with experimental ΔES‐T values. According to the literature, the stability of the benzynes in the singlet state is due to an effective interaction between the electrons of the biradical centers; however, this effect is completely reversed in the triplet state, which explains why the para isomer has the lowest ΔES‐T gap. [ABSTRACT FROM AUTHOR]

Herein the performance of a modification within the hybrid algorithm implemented in the AUTOMATON program is introduced and evaluated. For the creation of the initial population, AUTOMATON combines a probabilistic automata procedure with a genetic algorithm used to evolve this population. The proposed modification is addressed to efficiently identify the minimum energy structures of systems composed of more than one type of atom and with a low computational cost. The effectiveness of this approach is evaluated in the determination of the minimum energy structures of Be6B11−. The modification, aimed to explore the potential energy surface, consisted of filling the cells first with Be atoms in the process of creating the initial population. This order obeys the structural pattern established in the Be–B clusters reported to date. The results show that this variation not only identifies a more significant number of viable isomers but also to find a better putative global minimum than those previously reported in the literature. Therefore, it is recommended to be used as a complement to the standard searching process. [ABSTRACT FROM AUTHOR]