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Magnetic Bistability in Naphtho-1,3,2-dithiazolyl: Solid State Interconversion of a Thiazyl π-Radical and Its N-N
Demetris Bates1, Craig M Robertson1, Alicea A Leitch2
1Department of Chemistry , University of Liverpool , Liverpool L69 7ZD , United Kingdom.
Abstract:
Crystals of the heterocyclic radical naphtho-1,3,2-dithiazolyl NDTA display magnetic bistability with a well-defined hysteretic phase transition at Tc↓ = 128(2) K and Tc↑ = 188(2) K. The magnetic signature arises from a radical/dimer interconversion involving one of the two independent π-radicals in the P1̅ unit cell. Variable temperature X-ray crystallography has established that while all the radicals in HT-NDTA serve as paramagnetic ( S = 1/2) centers, half of the radicals in LT-NDTA form closed-shell N-N σ-bonded dimers ( S = 0) and half retain their S = 1/2 spin state. The wide window of bistability (60 K) may be attributed to the large structural changes that accompany the phase transition.
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