TY - JOUR
T1 - S = 1 Tetraazacyclophane Diradical Dication with Robust Stability
T2 - A Case of Low-Temperature One-Dimensional Antiferromagnetic Chain
AU - Wang, Wenqing
AU - Chen, Chao
AU - Shu, Chan
AU - Rajca, Suchada
AU - Wang, Xinping
AU - Rajca, Andrzej
N1 - Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/6/27
Y1 - 2018/6/27
N2 - One-dimensional (1D) spin-1 (S = 1) chain of organic radicals with low local magnetic anisotropy may provide a better understanding of the low-dimensional magnetism. We report solid-state studies, including single crystal X-ray crystallography, of air-stable tetraazacyclophane diradical dication salt 1 2·2+ ·2[Al(OC(CF 3 ) 2 CH 3 ) 4 ] - with a triplet ground state (ΔE ST ≈ 0.5 kcal mol -1 ). The magnetic behavior for 1 2·2+ at low temperature is best modeled by 1D spin S = 1 Heisenberg chain with intrachain antiferromagnetic coupling of J′/k = -5.4 K, which is associated with the interaryl C···C contacts, including π-π interactions. Zero-field splitting value, |D/hc| ≈ 5.6 × 10 -3 cm -1 , for 1 2·2+ is rather small; thus, the 1D chains are characterized by the high degree of isotropicity |D/2J′| ≈ 7.5 × 10 -4 . The diradical dication salt possesses extraordinary stability with onset of decomposition at temperature of about 180 °C (∼450 K), based on thermogravimetric analysis and EPR spectroscopy.
AB - One-dimensional (1D) spin-1 (S = 1) chain of organic radicals with low local magnetic anisotropy may provide a better understanding of the low-dimensional magnetism. We report solid-state studies, including single crystal X-ray crystallography, of air-stable tetraazacyclophane diradical dication salt 1 2·2+ ·2[Al(OC(CF 3 ) 2 CH 3 ) 4 ] - with a triplet ground state (ΔE ST ≈ 0.5 kcal mol -1 ). The magnetic behavior for 1 2·2+ at low temperature is best modeled by 1D spin S = 1 Heisenberg chain with intrachain antiferromagnetic coupling of J′/k = -5.4 K, which is associated with the interaryl C···C contacts, including π-π interactions. Zero-field splitting value, |D/hc| ≈ 5.6 × 10 -3 cm -1 , for 1 2·2+ is rather small; thus, the 1D chains are characterized by the high degree of isotropicity |D/2J′| ≈ 7.5 × 10 -4 . The diradical dication salt possesses extraordinary stability with onset of decomposition at temperature of about 180 °C (∼450 K), based on thermogravimetric analysis and EPR spectroscopy.
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U2 - 10.1021/jacs.8b02415
DO - 10.1021/jacs.8b02415
M3 - Article
C2 - 29863339
AN - SCOPUS:85048138065
SN - 0002-7863
VL - 140
SP - 7820
EP - 7826
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 25
ER -