A stable oxoverdazyl free radical: Structural and magnetic characterization

Michael John Plater, Steven Kemp, Eugenio Coronado, Carlos J. Gomez-Garcia, Ross W. Harrington, W. Clegg

Research output: Contribution to journalArticle

12 Citations (Scopus)

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. (c) 2006 Elsevier Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)2433-2438
Number of pages6
JournalPolyhedron
Volume25
Issue number12
DOIs
Publication statusPublished - Aug 2006

Keywords

  • oxoverdazyl
  • radical
  • antiferromagnetic
  • susceptibility
  • eelectron spin resonance
  • verdazyl radicals
  • weak ferromagnetism
  • crystal structures
  • p-cydov
  • spin
  • derivatives
  • exchange
  • 1,3,5-triphenyl-6-oxoverdazyl
  • 1,3,5-triphenylverdazyl
  • 6-oxoverdazyls

Cite this

A stable oxoverdazyl free radical : Structural and magnetic characterization. / Plater, Michael John; Kemp, Steven; Coronado, Eugenio; Gomez-Garcia, Carlos J.; Harrington, Ross W.; Clegg, W.

In: Polyhedron, Vol. 25, No. 12, 08.2006, p. 2433-2438.

Research output: Contribution to journalArticle

Plater, MJ, Kemp, S, Coronado, E, Gomez-Garcia, CJ, Harrington, RW & Clegg, W 2006, 'A stable oxoverdazyl free radical: Structural and magnetic characterization' Polyhedron, vol. 25, no. 12, pp. 2433-2438. https://doi.org/10.1016/j.poly.2006.02.007
Plater, Michael John ; Kemp, Steven ; Coronado, Eugenio ; Gomez-Garcia, Carlos J. ; Harrington, Ross W. ; Clegg, W. / A stable oxoverdazyl free radical : Structural and magnetic characterization. In: Polyhedron. 2006 ; Vol. 25, No. 12. pp. 2433-2438.
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T1 - A stable oxoverdazyl free radical

T2 - Structural and magnetic characterization

AU - Plater, Michael John

AU - Kemp, Steven

AU - Coronado, Eugenio

AU - Gomez-Garcia, Carlos J.

AU - Harrington, Ross W.

AU - Clegg, W.

PY - 2006/8

Y1 - 2006/8

N2 - 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. (c) 2006 Elsevier Ltd. All rights reserved.

AB - 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. (c) 2006 Elsevier Ltd. All rights reserved.

KW - oxoverdazyl

KW - radical

KW - antiferromagnetic

KW - susceptibility

KW - eelectron spin resonance

KW - verdazyl radicals

KW - weak ferromagnetism

KW - crystal structures

KW - p-cydov

KW - spin

KW - derivatives

KW - exchange

KW - 1,3,5-triphenyl-6-oxoverdazyl

KW - 1,3,5-triphenylverdazyl

KW - 6-oxoverdazyls

U2 - 10.1016/j.poly.2006.02.007

DO - 10.1016/j.poly.2006.02.007

M3 - Article

VL - 25

SP - 2433

EP - 2438

JO - Polyhedron

JF - Polyhedron

SN - 0277-5387

IS - 12

ER -