We found a match
Your institution may have rights to this item. Sign in to continue.
- Title
Structural, Magnetic, and Computational Correlations of Some Imidazolo-Fused 1,2,4-Benzotriazinyl Radicals.
- Authors
Constantinides, Christos P.; Berezin, Andrey A.; Manoli, Maria; Leitus, Gregory M.; Zissimou, Georgia A.; Bendikov, Michael; Rawson, Jeremy M.; Koutentis, Panayiotis A.
- Abstract
1,3,7,8-Tetraphenyl-4,8-dihydro-1 H-imidazolo[4,5 g][1,2,4]benzotriazin-4-yl ( 5), 8-(4-bromophenyl)-1,3,7-triphenyl-4,8-dihydro-1 H-imidazolo[4,5 g][1,2,4]benzotriazin-4-yl ( 6), and 8-(4-methoxyphenyl)-1,3,7-triphenyl-4,8-dihydro-1 H-imidazolo[4,5 g][1,2,4]benzotriazin-4-yl ( 7) were characterized by using X-ray diffraction crystallography, variable-temperature magnetic susceptibility studies, and DFT calculations. Radicals 5- 7 pack in 1 D π stacks made of radical pairs with alternate short and long interplanar distances. The magnetic susceptibility ( χ vs. T) of radicals 5 and 6 exhibit broad maxima at (50±2) and (50±4) K, respectively, and are interpreted in terms of an alternating antiferromagnetic Heisenberg linear chain model with average exchange-interaction values of J=−31.3 and −35.4 cm−1 ( gsolid=2.0030 and 2.0028) and an alternation parameter a=0.15 and 0.38 for 5 and 6, respectively. However, radical 7 forms 1 D columns of radical pairs with alternating distances; one of the interplanar distances is significantly longer than the other, which decreases the magnetic dimensionality and leads to discrete dimers with a ferromagnetic exchange interaction between the radicals (2 J=23.6 cm−1, 2 zJ′=−2.8 cm−1, gsolid=2.0028). Magnetic exchange-coupling interactions in 1,2,4-benzotriazinyl radicals are sensitive to the degree of slippage and inter-radical separation, and such subtle changes in structure alter the fine balance between ferro- and antiferromagnetic interactions.
- Subjects
IMIDAZOLES; BENZOTRIAZOLE; X-ray diffraction; MAGNETIC susceptibility; DENSITY functional theory
- Publication
Chemistry - A European Journal, 2014, Vol 20, Issue 18, p5388
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.201304538