Molecular structure and conformations of para-methylbenzene sulfonamide and ortho-methylbenzene sulfonamide:: Gas electron diffraction and quantum chemical calculations study
Molecular structure and conformations of para-methylbenzene sulfonamide and ortho-methylbenzene sulfonamide:: Gas electron diffraction and quantum chemical calculations study
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DOI：
10.1021/jp710532z
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发表时间：
2008-04-03
影响因子：
2.9
通讯作者：
Ivanov, Sergey N.
中科院分区：
文献类型：
--
作者：
Petrov, Vjacheslav M.;Girichev, Georgiy V.;Ivanov, Sergey N.
用气体电子衍射（GED）和量子化学方法（B3 LYP/6-311+G** 和MP2/6- 31 G **）研究了对甲苯磺酰胺（4-MBSA）和邻甲苯磺酰胺（2-MBSA）的分子结构和构象性质.量子化学计算预测4-MBSA存在两种构象，S-N键垂直于苯平面，NH 2基团覆盖或交错S-O键。的SO2组。两种构象都具有C-S对称性。在Delta E = 0.63 kcal/mol（B3 LYP）或1.00 kcal/mol（MP2）时，预计会出现重叠形式。计算结果表明，2-MBSA中的S-N键可以具有与甲基相反的平面方向（φ（C2 C1 SN）= 180 °）或非平面方向（φ（C2 C1 SN）约为60 °）。在这两种情况下，NH 2基团可以采用重叠或交错取向，导致总共四种稳定的构象。非平面重叠构象（C-1对称性）和平面重叠构象（C-S对称性）被预测是有利的。根据GED分析，在T = 151（3）° C下固体4-MBSA上的饱和蒸气由重叠（78（19）%）和交错（22（19）%）形式的混合物组成。在T = 157（3）℃下，固体2-MBSA上的饱和蒸气由非平面遮蔽（69（11）%）和平面遮蔽（31（11）%）形式的混合物组成。
The molecular structure and conformational properties of para-methylbenzene sulfonamide (4-MBSA) and ortho-methylbenzene sulfonamide (2-MBSA) have been studied by gas electron diffraction (GED) and quantum chemical methods (B3LYP/6-311+G** and MP2/6-31G**). Quantum chemical calculations predict the existence of two conformers for 4-MBSA with the S-N bond perpendicular to the benzene plane and the NH2 group either eclipsing or staggering the S-O bonds. of the SO2 group. Both conformers possess C-S symmetry. The eclipsed form is predicted to be favored by Delta E = 0.63 kcal/mol (B3LYP) or 1.00 kcal/mol (MP2). According to the calculations, the S-N bond in 2-MBSA can possess planar direction opposite the methyl group (phi C2C1SN) = 180 degrees) or nonplanar direction (phi(C2C1SN) approximate to 60 degrees). In both cases, the NH2 group can'adopt eclipsed or staggered orientation, resulting in a total of four stable conformers. The nonplanar eclipsed conformer (C-1 symmetry) and the planar eclipsed form (C-S symmetry) are predicted to be favored. According to the GED analysis, the saturated vapor over solid 4-MBSA at T = 151(3) degrees C consists as mixture of the eclipsed (78(19) %) and staggered (22(19) %) forms. The saturated vapor over solid 2-MBSA at T = 157(3) degrees C consists as a mixture of the nonplanar eclipsed (69(11) %) and planar eclipsed (31(11) %) forms.