Molecular conformation ofN,N′-diarylthioureas: An assessment by1H NMR and infrared spectroscopy
作者:L. V. Sudha、S. Manogaran、D. N. Sathyanarayana
DOI:10.1002/mrc.1260230802
日期:1985.8
Several N,N′‐dipyridyl‐ and N‐phenyl‐N′‐pyridyl‐thioureas were examined in different solvents at various temperatures by 1H NMR in order to study their conformational properties. The influence of concentration and the methyl substituent in the pyridine ring on the chemical shifts of the NH and pyridine groups was investigated. The observed chemical shifts are analysed in terms of the conformational properties
通过 1H NMR 在不同溶剂中在不同温度下检测了几种 N,N'-二吡啶基和 N-苯基-N'-吡啶基硫脲,以研究它们的构象特性。研究了浓度和吡啶环中的甲基取代基对NH和吡啶基团化学位移的影响。根据分子的构象特性分析观察到的化学位移。已经确定了关于 CN 键的内部旋转的自由能障碍。已测量红外光谱以补充核磁共振研究。分子内氢键在吡啶硫脲的优选构象中起主要作用。数据进一步揭示了对称 N 中发生的有趣的动态交换现象,
Structural Features of Tetraazathiapentalenes Fused with Pyrimidine and/or Pyridine Rings. Experimental Evaluation of the Nature of Hypervalent N−S−N Bond by Restricted Internal Rotation of the Pyrimidine Ring
dimethylated (17) 10-S-3 sulfuranes, derivatives of tetraazathiapentalenes fused with pyrimidine and/or pyridine ring, were prepared. These molecules are planar, and bond energies of the hypervalent N−S−N bond were evaluated by the temperature dependent restrictedrotation of the pyrimidine ring caused by cleavage of one of the S−N bonds. The bond length is longer, and the energy is lower for the S−N bond
制备了一系列中性 (8-10)、单甲基化 (12-14) 和二甲基化 (17) 10-S-3 硫烷,四氮杂硫戊烯与嘧啶和/或吡啶环稠合的衍生物。这些分子是平面的,高价 NS-N 键的键能通过由 SN 键之一断裂引起的嘧啶环的温度依赖性限制旋转来评估。与更多吸电子杂环稠合的 SN 键的键长更长,能量更低。