Magnetic exchange interactions in perfluorophenyl dithiadiazolyl radicals |
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Authors: | Jeremy M. Rawson Javier Luzon |
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Affiliation: | a Department of Chemistry, The University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK b Instituto de Ciencia de Materiales de Aragon, CSIC-Universidad de Zaragoza, E-50009, Zaragoza, Spain |
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Abstract: | EPR, electrochemical studies and neutron diffraction studies on a large range of 1,2,3,5-dithiadiazolyl radicals have shown that the spin density distribution is essentially unaffected by substituent effects. The variation of magnetic properties previously reported for a series of perfluorophenyl-dithiadiazolyl radicals p-XC6F4CNSSN (X = CN, Br, NO2 and NCC6F4) is therefore due to differences in molecular packing. The nearest-neighbour magnetic exchange interactions in these radicals are probed through DFT studies (B3LYP/6-311G**) and are shown to exhibit a variety of both ferromagnetic and antiferromagnetic interactions. All exchange interactions with |J| > 1 cm−1 coincide with close heterocyclic contacts between dithiadiazolyl rings (3.18-4.00 Å) and produce |J| values up to 40 K. An analysis of these interactions indicates that the dominant exchange pathway would appear to be a direct exchange mechanism between radical centres, with orthogonality of the singly-occupied molecular orbitals (SOMOs) favouring ferromagnetic interactions. |
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Keywords: | Dithiadiazolyl Organic magnet DFT Magnetostructural correlation |
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