|Posted on May 1, 2015 at 2:00 PM|
Our article with Dr. Óscar Jiménez-Halla (Univ. Guanajuato, Mexico) was selected as one of the six hot articles published in Dalton Transactions in December 2014. In this paper, we performed a theoretical study of the aromaticity in the neutral an anionic borole systems synthesized in the group of Prof. Holger Braunschweig. The results show that the neutral borole structures with four π electrons are antiaromatic and become increasingly more aromatic by addition of one and two electrons, in agreement with Hückel’s rule. While the uptake of one electron to the borole leads to a nonaromatic system, addition of a second electron fully aromatizes the ring and reliefs the system from its inherent electron deficiency. It is also shown that the exocyclic substituent at the boron atom has a considerable influence on the degree of antiaromaticity in the borole ring. Substituents with π-donating abilities, such as an amino or thiophene group, seem to mitigate the destabilizing electron delocalization in the ring, whereas π-accepting groups result in an enhanced antiaromatic destabilization.
(Artwork by J. Óscar C. Jiménez Halla)