constants and DeltaG(J)(av) values showed that the diequatorial conformer is predominant in the conformational equilibrium of the compounds studied at low temperature. However, DeltaG(PC)(av) data show that compounds 6 and 7 constitute an exception, since they are almost equally populated by ee and aa at room temperature, due to stabilization of their aa conformer by an intramolecular hydrogen bond. DeltaG(Ad)
3-X-
环己醇的构象平衡[X = F(1),Cl(2),Br(3),I(4),Me(5),NMe(2)(6)和MeO(7)]和3-X-甲氧基
环己烷[X = F(8),Cl(9),Br(10),I(11),Me(12),NMe(2)(13)和MeO(14)]顺式异构体由低温NMR光谱和PCMODEL计算的偶联常数确定。从这些数据(分别是DeltaG(J)(av)和DeltaG(PC)(av))以及通过可加性原理从单取代
环己烷(DeltaG(Ad))的数据中获得aa和ee构象异构体之间的能量差。 。H-1和H-3氢邻位偶合常数和DeltaG(J)(av)值表明,在低温下研究的化合物的构象平衡中,赤道构象异构体占主导地位。但是,DeltaG(PC)(av)数据表明,化合物6和7是一个例外,因为在室温下,由于ee和aa分子的氢键稳定了它们的aa构象异构体,因此它们在ee和aa上的分布几乎相等。根据