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A stable oxoverdazyl free radical: Structural and magnetic characterization

Lookup NU author(s): Stuart Kemp, Dr Ross Harrington, Emeritus Professor Bill Clegg

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Abstract

The structure and magnetic properties (susceptibility and ESR) of the stable oxoverdazyl free radical 6-(4-acetamidophenyl)-1,4,5,6-tetrahydro-2,4-dimethyl-1,2,4,5-tetrazin-3(2H)-one are presented. The crystal structure consists of chains of parallel planar molecules running along the b-axis. These chains are formed by dimers with a ring-over-bond overlap and a significant offset between dimers, although with similar inter- and intradimer distances. The susceptibility measurements show that this compound is an S = 1/2 paramagnet with weak antiferromagnetic interactions. The magnetic susceptibility can be very well reproduced with an antiferromagnetic regular chain model with g = 2.012(1) and an intrachain exchange parameter J = -1.54(1) K = -1.07(1) cm-1. Solid-state Q-band ESR spectra confirm the presence of an unpaired electron in the oxoverdazyl radical and the thermal behavior observed in the susceptibility measurements. Solution ESR spectrum show a very complicated spectrum with up to 13 hyperfine lines, some of them further splitted into three or more superhyperfine lines. A very satisfactory simulation of the shape, intensity and position of all the lines in this spectrum could be obtained with hyperfine coupling constants of 6.5 and 5.4 G for the two groups of two equivalent N atoms and 5.3 G for the six H atoms of the two methyl groups bonded to the verdazyl ring. © 2006 Elsevier Ltd. All rights reserved.


Publication metadata

Author(s): Plater MJ, Kemp S, Coronado E, Gomez-Garcia CJ, Harrington RW, Clegg W

Publication type: Article

Publication status: Published

Journal: Polyhedron

Year: 2006

Volume: 25

Issue: 12

Pages: 2433-2438

ISSN (print): 0277-5387

ISSN (electronic): 1873-3719

Publisher: Pergamon

URL: http://dx.doi.org/10.1016/j.poly.2006.02.007

DOI: 10.1016/j.poly.2006.02.007


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