取代杂氮硅三环的核磁共振及分子动力学研究

NMR and Molecular Dynamics Study on Some Substituted Silatranes

对取代的杂氮硅三环类化合物(Silatrane)-(3R,4S)-1-氯甲基杂氮硅三环-4-羧酸(1)和(3R,4S)-1-氯甲基-3-甲基杂氮硅三环-4-羧酸(2)及它们相应的三乙基铵盐(3)和(4)的结构采用~1H,^(13)C,^(29)Si NMR进行研究,其一维 ~1H NMR谱根据二维同核和异核相关谱进行了归属.从测得的偶合常数及化学位移分析,得出羧基及其铵盐的取代造成相邻另外两环上的—CH_2—CH_2—O—链上二面角发生扭拐,成为拐折旁式构象.分子动力学方法的模拟计算证明了这种构象变化.另外根据溶液中 ^(29)Si及~1H的化学位移实验结果,讨论了该类化合物环上取代对分子内配键(N—Si)的影响.

1H, 13C and 29Si NMR spectroscopy and molecular dynamics (MD) methods wereemployed to study the structure of the four synthesized silatrane compounds--(3R ,4S) - 1 -chloromethyl silatrane - 4 - carboxylic acid (1), (3R,4S) - 1 - chloromethyl - 3 - methyl -silatrane - 4 - carboxylic acid(2) ,and their corresponding triethylamine salts (3), (4). The 2D 1H -1H COSY and 13C- 1H COSY experiments and 1D spectrum simulation were carried out for assigning 1H NMR spectrum. From the NMR data, it was derived that the substitution of 4 -carboxylic acid group on the title compounds causes the atrane framework distorted, and the unsubstituted two adjacent -CH2-CH2-O- chains distorted as two staggered gauche conformations. The MD calculation supports the conclusion. Furthermore, no conformation transitions were found for the title compounds. The 29Si NMR data indicate that the N-Si dative bond is weakened slightly when the substitutions of the carboxyl group and corresponding salt group in the atrane framework happen, and the effect is stronger than that of the methyl substitution on the equatorial position of the atrane framework.