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
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Creator |
LATIF, IA
PANDA, A DATTA, SN |
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Subject |
density-functional theory
transition-metal-complexes broken symmetry approach magnetic-properties exchange interactions ab-initio electronic-structure verdazyl diradicals organic radicals mo calculations |
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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.
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Publisher |
AMER CHEMICAL SOC
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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 |
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Type |
Article
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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 |
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Language |
en
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