Conformational analysis and intramolecular/intermolecular interactions of N,N′-dibenzylideneethylenediamine derivatives

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• 作者：Hossein A. Dabbagh ; Mehdi Zamani ; Hossein Farrokhpour ; Mohammad Hossein Habibi ; Kazem Barati
• 关键词：X-ray structure ; Conformational analysis ; DFT ; NBO ; MO
• 刊名：Journal of Molecular Structure
• 出版年：2010
• 出版时间：1 November 2010
• 年：2010
• 卷：983
• 期：1-3
• 页码：169-185
• 全文大小：2736 K

文摘

The molecular structures, conformational stability and molecular energy profile of three derivatives of RC₆H₄CHNCH₂CH₂NCHC₆H₄R including N,N′-dibenzylideneethylenediamine (1, R = H), N,N′-bis(4-trifluoromethoxybenzylidene)ethylenediamine (2, R = OCF₃), and N,N′-bis(4-dimethylaminobenzylidene)ethylenediamine (3, R = N(CH₃)₂) were obtained at B3LYP/6-31++G^** and HF/6-31++G^** levels of theory and compared with X-ray single crystal structures. The conformation of 1 and 2 is anti, while that of 3 is gauche in solid state (X-ray geometry). Based on calculations, there are seven energy minima in potential energy curves. A gauche conformer of 1, 2 and 3 has the lowest energy minimum (in the calculations modeling gas phase conditions) among all the other conformers. This is in contrast to X-ray findings (solid phase) for 1 and 2 but complements the X-ray finding for 3. These results were analyzed by natural bond orbital (NBO) and molecular orbital (MO) to determine the role of intra- and/or intermolecular interactions in the crystal structures.