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Very Strongly Ferromagnetically Coupled Diradicals from Mixed Radical Centers. II. Nitronyl Nitroxide Coupled to Tetrathiafulvalene via Spacers

DSpace at IIT Bombay

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Title Very Strongly Ferromagnetically Coupled Diradicals from Mixed Radical Centers. II. Nitronyl Nitroxide Coupled to Tetrathiafulvalene via Spacers
 
Creator LATIF, IA
SINGH, VP
BHATTACHARJEE, U
PANDA, A
DATTA, SN
 
Subject density-functional theory
transition-metal-complexes
intramolecular magnetic interaction
broken symmetry approach
low-lying triplet
ab-initio ci
dft calculations
exchange interactions
imino-nitroxide
ground-state
 
Description We predict large and positive intramolecular magnetic exchange coupling constants (J) for coupled diradicals constructed from nitronyl nitroxide and tetrathiafulvalene monoradical moieties. These diradicals have the general formula TTF-coupler-NN, where the couplers are mostly aromatic systems. Unrestricted density functional methodology (UB3LYP) has been used to optimize the molecular geometries of the triplet diradicals using the 6-311 g(d,p) basis set. This has been followed by single-point UB3LYP calculations for triplet and broken symmetry (BS) states using 6-311++g(3df,3pd) basis and the optimized triplet geometries. We find that the species comprising of ethylene (geminal coupling) and pyridine as couplers have singlet ground states whereas the other species have triplet ground states. These findings are in support of the spin alternation rule. The largest J value we predict is 648.6 cm(-1) for the molecule with the spacer pyrrole. We also determine the percent weightings of triplet and singlet components in the BS state, estimate the diradical nature, and calculate the relative weights of different singlet and triplet component functions in the BS solution in each case.
 
Publisher AMER CHEMICAL SOC
 
Date 2011-07-15T04:44:42Z
2011-12-26T12:49:15Z
2011-12-27T05:35:04Z
2011-07-15T04:44:42Z
2011-12-26T12:49:15Z
2011-12-27T05:35:04Z
2010
 
Type Article
 
Identifier JOURNAL OF PHYSICAL CHEMISTRY A, 114(24), 6648-6656
1089-5639
http://dx.doi.org/10.1021/jp101433d
http://dspace.library.iitb.ac.in/xmlui/handle/10054/4156
http://hdl.handle.net/10054/4156
 
Language en