Stereomutation of Pentavalent Compounds: Validating the Berry Pseudorotation, Redressing Ugi’s Turnstile Rotation, and Revealing the Two- and Three-Arm Turnstiles

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• 作者：Erik P. A. Couzijn ; J. Chris Slootweg ; Andreas W. Ehlers ; Koop Lammertsma
• 刊名：Journal of the American Chemical Society
• 出版年：2010
• 出版时间：December 29, 2010
• 年：2010
• 卷：132
• 期：51
• 页码：18127-18140
• 全文大小：795K
• 年卷期：v.132,no.51(December 29, 2010)
• ISSN：1520-5126

文摘

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.p>