An Expanded Nucleophilicity Range of Metal Carbonyl Anions in Vinylic Substitution Reactions

Petr K. Sazonov ,  Galina A. Artamkina ,  Irina P. Beletskaya 

M.V. Lomonosov Moscow State University, Vorobyevy gory, Moscow 119992, Russian Federation

Abstract

Metal carbonyl anions ([M(CO)nL]-) are characterized by a very broad nucleophilicity span, which in aliphatic SN2 reactions increases by eight orders of magnitude from [Co(CO)4]- to supernucleophilic [CpFe(CO)2]-. Studying the nucleophilic vinylic substitution (SNV) reactions with [M(CO)nL]- anions [1] allowed us to compile a nucleophilicity scale of these anions in vinylic substitution (AdNE mechanism). The scale was obtained by combining the kinetic data from several overlapping series of [M(CO)nL]- anions reacting with vinyl halides of different activity (PhCF=CFHal, Ph(CN)C=CHHal, Ph(Cl)C=(CN)2, ets.). The nucleophilicity span of [M(CO)nL]- anions found in SNV reactions is twice as large as in aliphatic SN2 reactions, though good correlation exists between the NVinHal and log(k CH3I) parameters (see the Figure). The problem of interpreting the nucleophilicity data in terms of reaction mechanism, and the question whether it is indicative of latent single electron transfer (SET) step are to be discussed in the presentation.

Graph5.GIF

[1] P. K. Sazonov, V. A. Ivushkin, G. A. Artamkina, I. P. Beletskaya, Arkivoc 2003, Part (X), http://www.arkat-usa.org/ark/journal/2003/I10_Rossi-Ruveda/RR-839C/839C.pdf.

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Presentation: oral at 18th Conference on Physical Organic Chemistry, Symposium 1, by Petr K. Sazonov
See On-line Journal of 18th Conference on Physical Organic Chemistry

Submitted: 2006-02-01 10:48
Revised:   2009-06-07 00:44
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