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Very Strongly Ferromagnetically Coupled Diradicals from Mixed Radical Centers: Nitronyl Nitroxide Coupled to Oxoverdazyl via Polyene Spacers

DSpace at IIT Bombay

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Title Very Strongly Ferromagnetically Coupled Diradicals from Mixed Radical Centers: Nitronyl Nitroxide Coupled to Oxoverdazyl via Polyene Spacers
 
Creator LATIF, IA
PANDA, A
DATTA, SN
 
Subject density-functional theory
transition-metal-complexes
broken symmetry approach
magnetic-properties
exchange interactions
ab-initio
electronic-structure
verdazyl diradicals
organic radicals
mo calculations
 
Description We predict extremely large and positive intramolecular magnetic exchange coupling constants (J) for coupled diradicals constructed from nitronyl nitroxide (NN) and oxoverdazyl (o-VER). These radicals have the general formula o-VER(N)-nC-NN where nC represents an olefinic spacer with n = 0, 2, 4, 6, and 8. Species like o-VER(C)-nC-NN have negative coupling constants. The atoms in the parentheses show the point of attachment of the coupler to the verdazyl moiety. Both the N-linked series and C-linked series have comparable stability. The triplet molecular geometries were optimized by the density functional (UB3LYP) method using the 6-311 g(d,p) basis set. This was followed by single-point UB3LYP calculations using 6-311++g(3df,3pd) basis. To calculate J, single-point broken-symmetry computations were performed on the optimized triplet geometries and using the same basis set. The N-linked diradicals coupled through conjugated polyenes are topologically different. These are found to have coupling constants of the order of 1000 cm(-1), whereas the C-linked diradicals show coupling constants of the order of -100 cm(-1). In general, for both cases, the absolute magnitude of the coupling constant decreases with the increase in the length of the spacer.
 
Publisher AMER CHEMICAL SOC
 
Date 2011-07-15T04:37:41Z
2011-12-26T12:49:15Z
2011-12-27T05:35:04Z
2011-07-15T04:37:41Z
2011-12-26T12:49:15Z
2011-12-27T05:35:04Z
2009
 
Type Article
 
Identifier JOURNAL OF PHYSICAL CHEMISTRY A, 113(8), 1595-1600
1089-5639
http://dx.doi.org/10.1021/jp808314u
http://dspace.library.iitb.ac.in/xmlui/handle/10054/4155
http://hdl.handle.net/10054/4155
 
Language en