NMR AND MOLECULAR-DYNAMICS STUDY ON SOME SUBSTITUTED SILATRANES

H-1, C-13 and Si-29 NMR spectroscopy and molecular dynamics(MD) method s were employed to study the structure of the four synthesized silatra ne compounds - (3R,4S) - 1 - chloromethyl silatrane - 4 - carboxylic a cid(1), (3R,4S) - 1 - chloromethyl - 3 - methyl silatrane - 4 - carbox ylic acid (2), and their corresponding triethylamine salts (3), (4). T he 2D H-1 - H-1 COSY and C-13 - H-1 COSY experiments and 1D spectrum s imulation were carried out for assigning H-1 NMR spectrum. From the NM R data, it was derived that the substitution of 4 - carboxylic acid gr oup on the title compounds causes the atrane framework distorted, and the unsubstituted two adjacent -CH2-CH2-O- chains distorted as two sta ggered gauche conformations. The MD calculation supports the conclusio n. Furthermore, no conformation transitions were found for the title c ompounds. The Si-29 NMR data indicate that the N-Si dative bond is wea kened slightly when the substitutions of the carboxyl group and corres ponding salt group in the atrane framework happen, and the effect is s tronger than that of the methyl substitution on the equatorial positio n of the atrane framework.