Department of Chemistry and Pharmaceutical Sciences, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
J Am Chem Soc. 2010 Dec 29;132(51):18127-40. doi: 10.1021/ja105306s. Epub 2010 Nov 17.
A general reaction mechanism describes the qualitative change in chemical topology along the reaction pathway. On the basis of this principle, we present a method to characterize intramolecular substituent permutation in pentavalent compounds. A full description of the geometry around five-coordinate atoms using internal coordinates enables the analysis of the structural changes along the stereomutational intrinsic reaction coordinate. The fluxional behavior of experimentally known pentavalent phosphoranes, silicates, and transition-metal complexes has been investigated by density functional theory calculations, and three principal mechanisms have been identified: Berry pseudorotation, threefold cyclic permutation, and half-twist axial-equatorial interchange. The frequently cited turnstile rotation is shown to be equivalent to the Berry pseudorotation. In combination with graph theory, this approach provides a means to systematically investigate the stereomutation of pentavalent molecules and potentially identify hitherto-unknown mechanisms.
一个普遍的反应机制描述了沿着反应途径的化学拓扑的定性变化。基于这一原理，我们提出了一种方法来描述五配位化合物中分子内取代基的置换。使用内部坐标对五配位原子周围的几何形状进行全面描述，可以分析沿着构象内在反应坐标的结构变化。通过密度泛函理论计算，研究了实验已知的五价膦、硅酸盐和过渡金属配合物的流变性，并确定了三种主要机制：贝里假旋转、三重循环置换和半扭转轴向-赤道交换。经常被引用的转门旋转被证明等同于贝里假旋转。结合图论，这种方法提供了一种系统研究五价分子构象变化并可能识别以前未知机制的手段。
