Nucleophilic substitution at phosphorus (SN2@P): Disappearance and reappearance of reaction barriers

被引：0

作者：

Van Bochove, Marc A. ^{[1
]}

Swart, Marcel ^{[1
]}

Bickelhaupt, F. Matthias ^{[1
]}

机构：

[1] Afdeling Theoretische Chemie, Scheikundig Laboratorium, Vrije Universiteit, De Boelelaan 1083, NL-1081 HV Amsterdam, Netherlands

来源：

Journal of the American Chemical Society | 2006年 / 128卷 / 33期

关键词：

Pentacoordinate phosphorus species play a key role in organic and biological processes. Yet; their nature is still not fully understood; in particular; whether they are stable; intermediate transition complexes (TC) or labile transition states (TS). Through systematic; theoretical analyses of elementary SN2@C; SN2@Si; and SN2@P reactions; we show how increasing the coordination number of the central atom as well as the substituents' steric demand shifts the SN2@P mechanism stepwise from a single-well potential (with a stable central TC) that is common for substitution at third-period atoms; via a triple-well potential (featuring a pre- and post-TS before and after the central TC); back to the double-well potential (in which pre- and postbarrier merge into one central TS) that is well-known for substitution reactions at carbon. Our results highlight the steric nature of the SN2 barrier; but they also show how electronic effects modulate the barrier height. © 2006 American Chemical Society;

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摘要：

Journal article (JA)

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页码：10738 / 10744