Publication Type Journal Article
Title Dicyanoaromatic radical anions as mixed valence species
Authors Alvaro Moneo M Fernanda NN Carvalho J. P. Telo
Groups BioMol
Journal JOURNAL OF PHYSICAL ORGANIC CHEMISTRY
Year 2012
Month July
Volume 25
Number 7
Pages 559-565
Abstract The reduction of nine symmetric dicyanoaromatic radical anions by sodium amalgam in the presence of cryptand[2.2.2] was studied using cyclic voltammetry and using optical and electron paramagnetic resonance (EPR) spectroscopies in two aprotic solvents. All radicals are charge-delocalized (Class III) mixed valence species, as shown by the weak solvatochromism of their low-energy optical bands and by the vibrational structure exhibited by most of the bands. The maximum of the low-energy optical transition decreases logarithmically with the number of bonds (n) between cyano groups in a series of p-phenylene-bridged radicals, from p-phenyl (n?=?5) to p-quaterphenyl (n?=?17), although the energy of the latter lies higher than the value predicted by the linear regression. The energy of this band decreases linearly with the cos2 value of the torsion angle between phenyl rings in the spectra of biphenyl-4,4 -dicarbonitrile radical anion and their methyl-substituted derivatives. The fact that charge delocalization is maintained in radicals with non-Kekule bridges, with unusually large bridges and with bridges with highly twisted biphenyl systems suggests that cyano charge-bearing units have small reorganization energies and induce high electronic couplings through the bridges. Copyright (C) 2012 John Wiley \& Sons, Ltd.
DOI http://dx.doi.org/10.1002/poc.2905
ISBN
Publisher WILEY-BLACKWELL
Book Title
ISSN 0894-3230
EISSN
Conference Name
Bibtex ID ISI:000305183600007
Observations
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