1,3,2-二噻唑并[4,5-b]吡嗪-2-基中的双稳性和相变

Bistability and the phase transition in 1,3,2-dithiazolo[4,5-b]pyrazin-2-yl.

作者信息

Brusso Jaclyn L, Clements Owen P, Haddon Robert C, Itkis Mikhail E, Leitch Alicea A, Oakley Richard T, Reed Robert W, Richardson John F

机构信息

Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.

出版信息

J Am Chem Soc. 2004 Nov 17;126(45):14692-3. doi: 10.1021/ja044979q.

DOI:10.1021/ja044979q

PMID:15535673

Abstract

The molecular radical 1,3,2-dithiazolo[4,5-b]pyrazin-2-yl (PDTA) exhibits magnetic bistability just above room temperature, undergoing a well-defined hysteretic phase change with TC downward arrow = 297(1) K and TC upward arrow = 343(1) K. The crystal structures of the two phases of PDTA have been determined by single-crystal X-ray diffraction at 323(2) K. LT-PDTA consists of diamagnetic (S = 0) nearly superimposed pi-dimer stacks, while that of HT-PDTA comprises slipped stacks of pi-radicals (S = 1/2). The structural interconversion is suggested to proceed via the cooperative breaking and making of intermolecular S- - -N interactions and an inversion symmetry-preserving "domino cascade" of the pi-stacked rings.

摘要

分子自由基1,3,2 - 二噻唑并[4,5 - b]吡嗪 - 2 - 基（PDTA）在略高于室温时表现出磁双稳性，经历明确的滞后相变，其降温转变温度(T_{C↓}=297(1)K)，升温转变温度(T_{C↑}=343(1)K)。通过在323(2)K下的单晶X射线衍射确定了PDTA两个相的晶体结构。低温相PDTA由抗磁性（(S = 0)）且几乎重叠的π - 二聚体堆叠组成，而高温相PDTA则由π - 自由基（(S = 1/2)）的滑移堆叠组成。结构互变被认为是通过分子间S - - - N相互作用的协同断裂和形成以及π - 堆叠环的保持反演对称性的“多米诺级联”来进行的。