Natural bond orbital analysis of some S‐nitrosothiols biological molecules |
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Authors: | Li Xiao‐Hong Tang Zheng‐Xin Zhang Xian‐Zhou |
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Institution: | 1. College of Science, Henan University of Science and Technology, Luoyang 471003, China;2. College of Physics and Information Engineering, Henan Normal University, Xinxiang 453007, China |
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Abstract: | Theoretical study of several S‐nitrosothiols biological molecules has been performed using quantum computational ab initio RHF and density functional B3LYP and B3PW91 methods with 6‐31G(d,p) basis set. Geometries obtained from DFT calculations were used to perform natural bond orbital (NBO) analysis. It is noted that the weakness in the S? N sigma bond is due to nO1→σ delocalization and is responsible for the longer S? N bond length in S‐nitrosothiols. It is also noted that decreased occupancy of the localized σSN orbital in the idealized Lewis structure or increased occupancy of σ of the non‐Lewis orbital, and their subsequent impact on molecular stability and geometry (bond lengths) are related with the resulting p character of the corresponding sulfur natural hybrid orbital of σSN bond orbital. In addition, the charge transfer energy decreases with the increasing of the Hammett constants of substituent groups, and the partial charge distribution on the skeletal atoms shows that the electrostatic repulsion or attraction between atoms can give a significant contribution to the intramolecular and intermolecular interaction. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 |
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Keywords: | natural bond orbital S‐nitrosothiols second‐order delocalization energies natural hybrid orbital |
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