A quantum chemistry study: A new kind of boron nitrides

✍ Scribed by Qian Shu Li; Yu Xu

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 1002 KB
• Volume: 28
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/jcc.20558

✦ Synopsis

Abstract

At the B3LYP/6‐311+G** and the BP86/6‐311+G** levels of theory, BNN, H~3~BNN, NNBH~2~‐BH~2~NN, (BNN)~2~H~2~, NNBBNN, (BNN), (BNN)~4~, (BNN), (BNN), B~4~(NN)~2~, (BNN), (BNN)~6~, (BNN), and (BNN) are investigated. Neutral (BNN)~4~ is aromatic with its triplet state but antiaromatic with its singlet state. (BNN)~4~ dication favors D~2__d__~ structure, while (BNN)~4~ dianion favors a planar D~4__h__~ structure. (BNN), (BNN), (BNN), (BNN)~6~, (BNN), (BNN), (BNN), and (BNN) are all aromatic with planar monocyclic conformation, following the 4__n__ + 2 rule. Moreover, according to the CASSCF and MRCI calculations, the planar B~4~(NN)~2~ of D~2__h__~ symmetry prefers to be a σ‐π diradical in spite of open‐shell singlet or triplet and is also aromatic. Akin to the σ‐π back interaction in compounds containing transition metal, there exists the σ‐π back interaction between boron and N~2~ ligand among some species reported herein, which strengthens B^−^N bond but activates NN bond, especially in ^4^Σ^−^ BNN. The T‐shaped structure lies lowest in energy among seven isomers of the (BNN)~2~H~2~ dimer, and the parallel‐displaced structure is favored between two isomers of the (BNN)~6~ dimer. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007