A priori assessment of the stereoelectronic profile of phosphines and phosphites
A priori assessment of the stereoelectronic profile of phosphines and phosphites
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DOI：
10.1021/ja021254i
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发表时间：
2003-04-09
影响因子：
15
通讯作者：
Zhao, Y
中科院分区：
文献类型：
--
作者：
Cooney, KD;Cundari, TR;Zhao, Y
这项研究已经证明了一种经过严格校准的分子力学/半经验量子力学协议用于开发膦配体的立体电子(Tolman)图的实用性。对常用的烷基和芳基膦的计算分析表明，这些配体在立体电子结构上非常相似。对于大的、电子贫乏的磷化氢，观察到普通磷化氢的托尔曼图谱上有一个明显的差距。确定了几个符合这些标准的候选者，其中最有希望的是P(t-C4F9)(3)。磷参与环的膦具有非常有趣的立体电子性质，特别是那些连接的磷是三元环的一部分。在空间性质方面，在结晶学研究的基础上，用PM3(Tm)以足够的精度计算了Orpens及其同事提出的对称形变坐标，从而对新型膦化合物的预测具有很好的置信度。为了量化膦的电子性质，我们分析了改变辅助膦配体时CO伸缩频率的变化。
This research has demonstrated the utility of a rigorously calibrated, molecular mechanics/semiempirical quantum mechanical protocol for developing stereoelectronic (Tolman) maps for phosphine ligands. A computational analysis of alkyl and aryl phosphines in common usage suggests that these ligands are quite similar stereoelectronically. A noticeable gap in the Tolman map for common phosphines is observed for large, electron-poor phosphines. Several candidates meeting these criteria were identified, the most promising of which is P(t-C4F9)(3). Phosphines in which the phosphorus participates in a ring, which comprise a very small subset of reported phosphines, have very interesting stereoelectronic properties, particularly those in which the ligating phosphorus is part of a three-membered ring. In terms of steric properties, the symmetric deformation coordinate proposed by Orpen and co-workers on the basis of crystallographic studies is calculated with sufficient accuracy using PM3(tm) to allow good confidence in predictions of novel phosphines. For quantification of the electronic properties of phosphines, we analyzed changes in the CO stretching frequency upon changing the ancillary phosphine ligands.