Probing magnetic exchange interactions in molecular magnets: an inclusion compound of a dithiadiazolyl radical

Langley, Philip J.; Rawson, Jeremy M.; Smith, J. Nicholas B.; Schüler, Matthias; Bachmann, Rainer; Schweiger, Arthur; Palácio, Fernando; Antorrena, Guillermo; Gescheidt, Georg; Quintel, Andrea; Rechsteiner, Peter; Hulliger, Jürg

doi:10.1039/a901045i

Cited by 37 publications

(23 citation statements)

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“…However, given that the unpaired spin density on the cyano N atom is negligible, then magnetic exchange through this intermolecular contact should be considered negligible. Recently, Langley et al [34] incorporated the related radical, p-NCC 6H4 CNSSN into a channel structure with molecules in the channels linked in a head-to-tail fashion and found no indica- tion of magnetic exchange through this CN...S contact. In addition to this close CN...S contact, each molecule has four longer intermolecular S...N contacts (at ca.…”

Section: Discussionmentioning

confidence: 99%

A CW-EPR and ESEEM spectroscopic study of the dithiadiazolyl radicals p-XC6F4CNSSN (X = CN, Br)

et al. 2001

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Two dithiadiazolyl radicals, p-NCC6F4CNSSN and p-BrC 6 F4CNSSN, have recently been found to be paramagnetic in the solid state. While the (3-phase of the first one exhibits spontaneous magnetization below 36 K, the second one shows a paramagnetic character in the solid state. The spin density distribution in these radicals is examined through continuous-wave electron paramagnetic resonance and electron spin echo envelope modulation spectroscopies. Hyperfine correlation sublevel spectroscopy provides information about the interaction of the unpaired spin with F and N nuclei. A signal coming from the interaction with Br nucleus is also detected. The superhyperfine coupling constants of the unpaired electron with the magnetic nuclei are obtained and values of the corresponding spin densities, f and f -f, can be estimated in the isolated radicals. Spin density distribution has also been calculated in both molecules with density functional theory, being in excellent agreement with those determined from the spectra. The spin density is mainly concentrated in the dithiadiazolyl ring, but some spin density is observed on the fluorinated aromatic rings. They also provide a strong basis to understand the differences of the magnetic behavior of both molecules in terms of their respective packing in the solid state.

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Section: Discussionmentioning

confidence: 99%

A CW-EPR and ESEEM spectroscopic study of the dithiadiazolyl radicals p-XC6F4CNSSN (X = CN, Br)

et al. 2001

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“…Previous magnetic studies on thiazyl radicals [6,[11][12][13][14][15] have shown that magnetic interactions propagate through inter-molecular S···N contacts. In the case of 5, the near orthogonal nature of the singly occupied molecular orbitals on neighboring molecules would appear to lead to a ferromagnetic interaction.…”

Section: Methodsmentioning

confidence: 99%

A Thiazyl‐Based Organic Ferromagnet

et al. 2003

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In 1928 Heisenberg proposed [1] that bulk ferromagnetic order would only ever be achieved in systems containing heavy atoms, that is, metals, their oxides, and related derivatives. Indeed it was not until 1991 that the first organic ferromagnet was reported; the b-polymorph of the para-nitrophenyl nitronyl nitroxide radical (p-NPNN, 1; Scheme 1) was shown to order below 0.6 K. [2] Since then a number of other purely organic radicals have been found to undergo bulk ferromagnetic order, although the majority order below 1 K. Exceptions include the radical cation salts [C 60 ][TDAE] [3] (TDAE = tetrakis(dimethylamino)ethylene) and [BBDTA]-GaCl 4 [4](3; BBDTA = benzobis(1,3,2-dithiazolyl), which order as ferromagnets at 16 and 6.7 K, respectively. Of the neutral radicals, only the nitroxide-based diradical DOTM-DAA (2; DOTMDAA = N,N'-dioxy-1,3,5,7-tetramethyl-2,6diazaadamantane) orders ferromagnetically above 1 K (T c = 1.48 K), [5] although the dithiadiazolyl radical p-NCC 6 F 4 CNSSNC (4) orders as a weak ferromagnet at 36 K under ambient pressure, [6] the highest reported temperature for magnetic ordering in an organic radical. We have sought to prepare new dithiadiazolyl radicals, closely related to 4, in which small structural changes may lead to new magnetically ordered systems. Here we report the structure and magnetic properties of 5, which is only the second neutral organic radical to order as a ferromagnet above 1 K.

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“…Detailed studies on 1β and the related inclusion complex PHTP.p-NCC 6 H 4 CNSSN [16] support a dominant magnetic exchange pathway in 1 via interchain exchange interactions through close intermolecular S…N contacts. In 1β the geometry supports an antiferromagnetic ground state.…”

Section: Discussionmentioning

confidence: 99%

Synthesis and Magnetic Properties of the Novel Dithiadiazolyl Radical, p-NCC6F4C6F4CNSSN

et al. 2004

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Abstract:The dithiadiazolyl radical p-NCC 6 F 4 C 6 F 4 CNSSN• (4) retains its monomeric nature in the solid state with molecules linked together into chains via supramolecular CN···S interactions. Variable temperature magnetic studies on 4 show that it behaves as a near-ideal Curie paramagnet (|θ| less than 0.1 K), indicating negligible intermolecular exchange. The effective magnetic moment (1.78 µ B ) is temperature independent and in excellent agreement with the value expected for an S = ½ paramagnet with g = 2.01 (1.74µ B ). The lack of exchange coupling between radicals is attributed to the absence of significant orbital overlap between radical centres.

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Probing magnetic exchange interactions in molecular magnets: an inclusion compound of a dithiadiazolyl radical

Cited by 37 publications

References 10 publications

A CW-EPR and ESEEM spectroscopic study of the dithiadiazolyl radicals p-XC6F4CNSSN (X = CN, Br)

A CW-EPR and ESEEM spectroscopic study of the dithiadiazolyl radicals p-XC6F4CNSSN (X = CN, Br)

A Thiazyl‐Based Organic Ferromagnet

Synthesis and Magnetic Properties of the Novel Dithiadiazolyl Radical, p-NCC6F4C6F4CNSSN

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