WHAT HAPPENS TO FORMAMIDE DURING C-N BOND ROTATION - ATOMIC AND MOLECULAR ENERGETICS AND MOLECULAR REACTIVITY AS A FUNCTION OF INTERNAL-ROTATION
WHAT HAPPENS TO FORMAMIDE DURING C-N BOND ROTATION - ATOMIC AND MOLECULAR ENERGETICS AND MOLECULAR REACTIVITY AS A FUNCTION OF INTERNAL-ROTATION
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DOI：
10.1139/v93-116
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发表时间：
1993-06-01
期刊：
影响因子：
--
通讯作者：
CAMERON, LM
中科院分区：
文献类型：
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作者：
LAIDIG, KE;CAMERON, LM
本文采用HF/6-31G**//HF/6-31G**理论，在分子和原子水平上研究了甲酰胺中C-N键的旋转动力学。在分子水平上，旋转障碍是由于旋转远离平面构象时总吸引能的减少，主要是由于C-N键的延长。在原子水平上，势垒是由于氮和它的键邻居之间的原子间吸引力的损失。我们利用反应性的拉普拉斯模型研究了甲酰胺对氮和氧的亲电攻击以及羰基碳的亲核攻击的敏感性作为C-N键旋转的函数。该模型预测羰基碳对亲核攻击的敏感性在O-C-N-H扭转角为60度时达到最大值。作为溶剂场的模拟，我们利用均匀电场研究了溶剂化对这些预测的影响。这种几何-反应性关系与提出的多肽酶催化活化模型有关。
We investigate the energetics of rotation about the C-N bond in formamide at the molecular and atomic levels using the HF/6-31G**//HF/6-31G** level of theory. At the molecular level, the barrier to rotation results from a decrease in overall attractive energies upon rotation away from the planar conformation, primarily due to the lengthening of the C-N bond. At the atomic level, the barrier is due to the loss in interatomic attraction between the nitrogen and its bonded neighbors. We investigate the susceptibility of formamide to electrophilic attack at nitrogen and oxygen as well as nucleophilic attack at carbonyl carbon as a function of C-N bond rotation using the Laplacian model of reactivity. The model predicts the susceptibility to nucleophilic attack at carbonyl carbon to reach a maximum with a O-C-N-H torsional angle of 60-degrees. As a mimic of solvent fields, we investigate the effect of solvation upon these predictions with the application of homogeneous electric fields. This geometry-reactivity relationship is related to proposed models of activation in the enzymatic catalysis of peptides.