An N→π* Interaction Reduces the Electrophilicity of the Acceptor Carbonyl Group

Overview

Journal Chem Commun (Camb)

Publisher Royal Society of Chemistry

Specialty Chemistry

Date 2013 Aug 10

PMID 23928794

Citations 11

Authors

Amit Choudhary

Charles G Fry

Kimberli J Kamer

Ronald T Raines

Affiliations

Soon will be listed here.

Abstract

Carbonyl-carbonyl (C=O···C'=O') interactions are ubiquitous in both small and large molecular systems. This interaction involves delocalization of a lone pair (n) of a donor oxygen into the antibonding orbital (π*) of an acceptor carbonyl group. Analyses of high-resolution protein structures suggest that these carbonyl-carbonyl interactions prefer to occur in pairs, that is, one donor per acceptor. Here, the reluctance of the acceptor carbonyl group (C'=O') to engage in more than one n→π* electron delocalization is probed using imidazolidine-based model systems with one acceptor carbonyl group and two equivalent donor carbonyl groups. The data indicate that the electrophilicity of the acceptor carbonyl group is reduced when it engages in n→π* electron delocalization. This diminished electrophilicity discourages a second n→π* interaction with the acceptor carbonyl group.

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