A Structural Study of Selenobenzamides: Crystal Structures and Dynamic 13C NMR
A Structural Study of Selenobenzamides: Crystal Structures and Dynamic 13C NMR
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硒代苯甲酰胺的结构研究：晶体结构和动态 13C NMR
DOI：
10.1002/cber.19971300108
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
A. D. Gen
中科院分区：
文献类型：
--
作者：
P. Otten;S. Gorter;A. D. Gen
用X射线衍射法测定了对溴硒苯甲酰基吗啉（2a）和[对二甲氨基硒苯甲酰基]吗啉（2b）的固态结构。两种分子都显示出平坦的硒代酰胺基团。携带对二甲氨基取代基的芳环对共振稳定的较大贡献由芳环与硒代酰胺基团之间的较小面间角Θ [53.3（1）° vs.81.1（1）°]和CSe键的较短长度[1.824（5）A vs.1.840（3）A]反映。用动态~（13）C NMR测定了5种对位取代（硒代苯甲酰基）吗啉类化合物的C-N键旋转活化吉布斯自由能（ΔG_（？）发现活化势垒的范围从61.6 kJ/mol（X = NNMe 2）到75.1 kJ/mol（X = H）。发现相应的（硫代苯甲酰基）吗啉的ΔG_（？）R值从3.2 kJ/mol（X = NMe_2）降低到5.0 kJ/mol（X = H）。在这两种情况下，ΔG Δ G与s+ p都表现出良好的线性Hammett相关性。
The solid-state structures of (p-bromoselenobenzoyl)morpholine (2a) and [p-(dimethylamino)selenobenzoyl]morpholine (2b) were determined by X-ray diffraction. Both molecules show a flat selenoamide group. The larger contribution of resonance stabilization by the aromatic ring carrying the p-dimethylamino substituent is reflected by the smaller interplanar angle Θ between the aromatic ring and the selenoamide group [53.3(1)° vs. 81.1(1)°] and by the shorter length of the CSe bond [1.824(5) A vs. 1.840(3) A]. The Gibbs free energy of activation of C-N bond rotation (ΔG≠rot) of five p-substituted (selenobenzoyl)morpholines was determined by dynamic 13C NMR. The activation barriers were found to range from 61.6 kJ/mol (X = NNMe2) to 75.1 kJ/mol (X = H). The ΔG≠rot values of the corresponding (thiobenzoyl)morpholines were found to be from 3.2 kJ/mol (X = NMe2) to 5.0 kJ/mol (X = H) lower. In both cases, ΔG≠rot showed an excellent linear Hammett correlation with s+p.