Author:
Humphreys Robert W. R.,Arnold Donald R.
Abstract
An analysis of the temperature dependence (4–30 K) of the electron spin resonance (esr) spectra of substituted diphenylmethylenes (e.g. para-, para′-; methoxy, cyano, dimethylamino, and nitro) indicates all of these species have a triplet ground state. The variation in the zero-field splitting parameter D for this series of methylenes provides evidence that the average separation of the unpaired electrons is greatest for the unsymmetrically substituted derivatives, those having a strong para-electron-withdrawing substituent and a strong para′-electron-donating substituent. This result is explained in terms of a favourable contribution of charge-separated valence-bond structures, i.e., merostabilization.
Publisher
Canadian Science Publishing
Subject
Organic Chemistry,General Chemistry,Catalysis
Cited by
40 articles.
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