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Theoretical Studies on Energetic Property and Stability of Pyrazine and Pyridine Derivatives
Author(s) -
Fan Xiaowei,
Gu Chenggang,
Chen Gong,
Ju Xuehai
Publication year - 2010
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.201190005
Subject(s) - chemistry , pyrazine , homolysis , pyridine , isodesmic reaction , bond dissociation energy , hydrogen bond , intramolecular force , computational chemistry , heterolysis , density functional theory , dissociation (chemistry) , photochemistry , medicinal chemistry , organic chemistry , molecule , radical , catalysis
Density functional calculations at the B3LYP level with 6‐311G** and aug‐cc‐pVDZ basis sets were performed to predict the heats of formation (HOFs) for two pyrazine derivatives and eight pyridine derivatives. In the isodesmic reactions designed for the computation of heats of formation (HOFs), pyrazine and pyridine were chosen as reference compounds. The N ‐oxidations for the ring nitrogen of pyrazine and pyridine derivatives decrease the HOF values when N ‐oxide oxygen is neighboring with amino groups, but increase when it neighbors with nitro groups. Thermal stability was evaluated via bond dissociation energies (BDE) at the UB3LYP/6‐311G** level. As a whole, the homolysis of C–NO 2 bonds is the main step for bond dissociation of the title compounds. The BDE values of title compounds are influenced by intramolecular hydrogen bonds. The hydrogen bond effects associated with the length of the H···O bonds were analyzed by the electron density at the critical points and natural bond orbital.