Abu-Zaied Mamdouh A, Nawwar Galal A, Elgemeie Galal H, Jones Peter G
Green Chemistry Department, Chemical Industries Research Institute, National Research Centre, Dokki, Giza 12622, Egypt.
Chemistry Department, Faculty of Science, Helwan University, Cairo, Egypt.
Acta Crystallogr E Crystallogr Commun. 2024 Jul 9;80(Pt 8):829-839. doi: 10.1107/S2056989024006455. eCollection 2024 Aug 1.
The compounds 2',3',4',6'-tetra--acetyl-β-d-gluco-pyranosyl '-cyano--phenyl-carbamimido-thio-ate (CHNOS, ), 2',3',4',6'-tetra--acetyl-β-d-galacto-pyranosyl '-cyano-phenyl-carbamimido-thio-ate, (CHNOS, ), 2',3',4',6'-tetra--acetyl-β-d-galacto-pyranosyl '-cyano--methyl-carbamimido-thio-ate (CHNOS, ), and 2',3',4',6'-tetra--acetyl-β-d-galacto-pyranosyl '-cyano---tolyl-carbamimido-thio-ate (CHNOS, ) all crystallize in 222 with = 4. For all four structures, the configuration across the central (formal) C=N(CN) double bond of the carbamimido-thio-ate group is . The torsion angles C5-O1-C1-S (standard sugar numbering) are all close to 180°, confirming the β position of the substituent. Compound involves an intra-molecular hydrogen bond N-H⋯O1; in this contact is the weaker branch of a three-centre inter-action, whereas in and the H⋯O distances are much longer and do not represent significant inter-actions. The C-N bond lengths at the central carbon atom of the carbamimido-thio-ate group are almost equal. All C-O-C=O torsion angles of the acetyl groups correspond to a synperiplanar geometry, but otherwise all four mol-ecules display a high degree of conformational flexibility, with many widely differing torsion angles for equivalent groups. In the crystal packing, , and form layer structures involving the classical hydrogen bond N-H⋯N and a variety of 'weak' hydrogen bonds C-H⋯O or C-H⋯S. The packing of is almost featureless and involves a large number of borderline 'weak' hydrogen bonds. In an appendix, a potted history of wavelength preferences for structure determination is presented and it is recommended that, even for small organic crystals in non-centrosymmetric space groups, the use of Mo radiation should be considered.
化合物2',3',4',6'-四乙酰基-β-D-吡喃葡萄糖基'-氰基-苯基-氨基硫代甲酸酯（CHNOS ）、2',3',4',6'-四乙酰基-β-D-吡喃半乳糖基'-氰基-苯基-氨基硫代甲酸酯（CHNOS ）、2',3',4',6'-四乙酰基-β-D-吡喃半乳糖基'-氰基-甲基-氨基硫代甲酸酯（CHNOS ）和2',3',4',6'-四乙酰基-β-D-吡喃半乳糖基'-氰基-对甲苯基-氨基硫代甲酸酯（CHNOS ）均以空间群222结晶，晶胞参数a = 4。对于所有这四种结构，氨基硫代甲酸酯基团中心（形式上的）C=N(CN)双键两侧的构型均为反式。扭转角C5-O1-C1-S（标准糖编号）均接近180°，证实了取代基的β位。化合物 涉及分子内氢键N-H⋯O1；在 中，这种接触是三中心相互作用中较弱的分支，而在 和 中，H⋯O距离长得多，并不代表显著的相互作用。氨基硫代甲酸酯基团中心碳原子处的C-N键长几乎相等。乙酰基的所有C-O-C=O扭转角均对应于顺叠式几何构型，但除此之外，所有四个分子均表现出高度的构象灵活性，等效基团的扭转角差异很大。在晶体堆积中， 、 和 形成层状结构，涉及经典氢键N-H⋯N以及各种“弱”氢键C-H⋯O或C-H⋯S。 的堆积几乎没有特征，涉及大量临界“弱”氢键。在附录中，给出了结构测定波长偏好的简要历史，并建议即使对于非中心对称空间群中的小有机晶体，也应考虑使用钼辐射。
