GENERAL DEFINITION OF RING PUCKERING COORDINATES
GENERAL DEFINITION OF RING PUCKERING COORDINATES
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DOI：
10.1021/ja00839a011
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发表时间：
1975-01-01
影响因子：
15
通讯作者：
POPLE, JA
中科院分区：
文献类型：
--
作者：
CREMER, D;POPLE, JA
定义了一般单圈褶环的唯一平均平面。相对于该平面的褶皱几何由振幅和相位坐标来描述，这些坐标是Kilpatrick、Pitzer和Spitzer为环戊烷引入的坐标的推广。与早期基于扭转角的治疗不同，该方法不涉及数学近似。对四元环、五元环和六元环的简要介绍说明了这一概念的实用性。尽管许多环状化合物中闭环的非平面性多年来得到了广泛的认识，但在其定量描述方面仍存在一些困难。基尔-帕特里克、皮策和斯皮策在1947年讨论环戊烷的分子结构时迈出了重要的第一步。1从平面正五边形的离面情绪的正常模式出发，2他们指出，y个碳原子垂直于平面的位移可以写成
A unique mean plane is defined for a general monocyclic puckered ring. The geometry of the puckering relative to this plane is described by amplitude and phase coordinates which are generalizations of those introduced for cyclopentane by Kilpatrick, Pitzer, and Spitzer. Unlike earlier treatments based on torsion angles, no mathematical approximations are involved. A shorttreatment of the four-, five-, and six-membered ring demonstrates the usefulness of this concept. Finally, an example is given of theanalysis of crystallographic structural data interms of these coordinates.Although the nonplanar character of closed rings in many cyclic compounds has been widely recognized for many years, there remain some difficulties in its quantitative specification. An importantfirst step was taken by Kil-patrick, Pitzer, and Spitzer intheir 1947 discussion of the molecular structure of cyclopentane. 1 Starting with the nor-mal modes of out-of-planemotions of a planar regular pentagon, 2 they pointed out that displacement of the y'th car-bon atom perpendicular to the plane could be written