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PCM study of the solvent and substituent effects on bond dissociation energies of the CNO bond
Author(s) -
Li XiaoHong,
Tang ZhengXin,
Yang XiangDong
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.21952
Subject(s) - substituent , chemistry , bond dissociation energy , computational chemistry , basis set , molecule , dissociation (chemistry) , quantum chemical , density functional theory , solvent , stereochemistry , organic chemistry
Quantum chemical calculations are used to estimate the equilibrium CNO bond dissociation energies (BDEs) for eight XNO molecule (X = CCl 3 , C 6 F 5 , CH 3 , CH 3 CH 2 , iC 3 H 7 , tC 4 H 9 , CH 2 CHCH 2 , and C 6 H 5 CH 2 ). These compounds are studied by employing the hybrid density functional theory (B3LYP, B3PW91, B3P86) methods together with 6‐31G** and 6‐311G** basis sets and the complete basis set (CBS‐QB3) method. The obtained results are compared with the available experimental results. It is demonstrated that B3P86/6‐31G** and CBS‐QB3 methods are accurate for computing the reliable BDEs for the XNO molecule. Considering the inevitably computational cost of CBS‐QB3 method and the reliability of the B3P86 calculations, B3P86 method with 6‐31G** basis set may be more suitable to calculate the BDEs of the CNO bond. The solvent effects on the BDEs of the CNO bond are analyzed and it is shown that the CNO BDEs in a vacuum computed by using B3PW91/6‐311G** method are the closest to the computed values in acetontrile and the average solvent effect is 1.48 kcal/mol. Subsequently, the substituent effects of the BDEs of the CNO bond are further analyzed and it is found that electron denoting group stabilizes the radical and as a result BDE decreases; whereas electron withdrawing group stabilizes the group state of the molecule and thus increases the BDE from the parent molecule. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009