Mambourg Kalina, Bodart Laurie, Tumanov Nikolay, Lanners Steve, Wouters Johan
Departement of Chemistry, University of Namur, Rue de Bruxelles 61, Namur 5000, Belgium.
Acta Crystallogr C Struct Chem. 2020 Mar 1;76(Pt 3):205-211. doi: 10.1107/S2053229620000996. Epub 2020 Feb 7.
The condensation reaction of 2-mercapto-3-methoxybenzaldehyde with 3-aminopyridine afforded an unexpected N-alkylated [1,5]dithiocine instead of the N-salicylideneaniline. The proposed mechanism for this condensation involves a strong intramolecular hydrogen bond between the thiol and the amine groups, leading to a second condensation. The corresponding product, i.e. 4,10-dimethoxy-13-(pyridin-3-yl)-6H,12H-6,12-epiminodibenzo[b,f][1,5]dithiocine methanol 0.463-solvate, CHNOS·0.463CHOH, was characterized by single-crystal X-ray diffraction analysis. The supramolecular structure shows π-π stacking and S...S interactions in the crystal packing. Within the asymmetric unit, two geometries of the N atom are observed. Although a planar geometry should be expected, a pyramidal one is observed due to the crystal packing. The presence of the two geometries was further supported by density functional theory (DFT) calculations that show an electronic energy difference of less than 2 kJ mol between the two conformers.
2-巯基-3-甲氧基苯甲醛与3-氨基吡啶的缩合反应得到了意想不到的N-烷基化[1,5]二硫辛因，而不是N-水杨醛苯胺。该缩合反应的 proposed 机制涉及硫醇和胺基之间的强分子内氢键，导致第二次缩合。相应的产物，即4,10-二甲氧基-13-(吡啶-3-基)-6H,12H-6,12-亚氨基二苯并[b,f][1,5]二硫辛因甲醇0.463溶剂化物，CHNOS·0.463CHOH，通过单晶X射线衍射分析进行了表征。超分子结构在晶体堆积中显示出π-π堆积和S...S相互作用。在不对称单元内，观察到N原子的两种几何构型。尽管应该预期为平面几何构型，但由于晶体堆积，观察到的是金字塔形。密度泛函理论(DFT)计算进一步支持了两种几何构型的存在，计算表明两种构象之间的电子能量差小于2 kJ mol。
