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Broken-symmetry density functional theory investigation on bis-nitronyl nitroxide diradicals: Influence of length and aromaticity of couplers

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Title Broken-symmetry density functional theory investigation on bis-nitronyl nitroxide diradicals: Influence of length and aromaticity of couplers
 
Creator ALI, ME
DATTA, SN
 
Subject intramolecular magnetic interaction
exchange coupling-constants
transition-metal-complexes
ab-initio
binuclear complexes
imino nitroxide
ground-state
effective-hamiltonians
orbital interactions
dft calculations
 
Description A series of nitronyl nitroxide (NN) diradicals with linear conjugated couplers and another series with aromatic couplers have been investigated by the broken-symmetry (BS) DFT approach. The overlap integral between the magnetically active orbitals in the BS state has been explicitly computed and used for the evaluation of the magnetic exchange coupling constant (J). The calculated J values are in very good agreement with the observed values in the literature. The magnitude of J depends on the length of the coupler as well as the conformation of the radical units. The aromaticity of the spacer decreases the strength of the exchange coupling constant. The SOMO-SOMO energy splitting analysis, where SOMO stands for the singly occupied molecular orbital, and the calculation of electron paramagnetic resonance (EPR) parameters have also been carried out. The computed hyperfine coupling constants support the intramolecular magnetic interactions. The nature of magnetic exchange coupling constant can also be predicted from the shape of the SOMOs as well as the spin alternation rule in the unrestricted. Hartree-Fock (UHF) treatment. It is found that 7-conjugation along with the spin-polarization plays the major role in controlling the magnitude and sign of the coupling constant.
 
Publisher AMER CHEMICAL SOC
 
Date 2011-07-13T18:02:18Z
2011-12-26T12:48:01Z
2011-12-27T05:43:12Z
2011-07-13T18:02:18Z
2011-12-26T12:48:01Z
2011-12-27T05:43:12Z
2006
 
Type Article
 
Identifier JOURNAL OF PHYSICAL CHEMISTRY A, 110(8), 2776-2784
1089-5639
http://dx.doi.org/10.1021/jp057083w
http://dspace.library.iitb.ac.in/xmlui/handle/10054/3737
http://hdl.handle.net/10054/3737
 
Language en