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A quantum chemistry study: A new kind of boron nitrides
Author(s) -
Li Qian Shu,
Xu Yu
Publication year - 2007
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.20558
Subject(s) - diradical , dication , antiaromaticity , chemistry , singlet state , crystallography , density functional theory , dimer , computational chemistry , valence (chemistry) , aromaticity , molecule , excited state , atomic physics , physics , organic chemistry
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) 3 + , (BNN) 4 , (BNN) 4 2+ , (BNN) 4 2− , B 4 (NN) 2 , (BNN) 5 − , (BNN) 6 , (BNN) 7 + , and (BNN) 8 2+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) 3 + , (BNN) 4 2− , (BNN) 5 − , (BNN) 6 , (BNN) 7 + , (BNN) 7 3− , (BNN) 8 2+ , and (BNN) 8 2−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 NN 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