Magnetostructural Relationship in the Spin-Crossover Complex t-{Fe(abpt)2[N(CN)2]2}: Polymorphism and Disorder Phenomenon

详细信息    查看全文

• 作者：Chou-Fu Sheu ; Sé ; bastien Pillet ; Yen-Chen Lin ; Szu-Miao Chen ; I-Jui Hsu ; Claude Lecomte ; Yu Wang
• 刊名：Inorganic Chemistry
• 出版年：2008
• 出版时间：December 1, 2008
• 年：2008
• 卷：47
• 期：23
• 页码：10866-10874
• 全文大小：299K
• 年卷期：v.47,no.23(December 1, 2008)
• ISSN：1520-510X

文摘

t-{Fe(abpt)₂[N(CN)₂]₂} [abpt = 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole] is an intriguing spin-crossover system that crystallizes in two polymorphs. Polymorph A is paramagnetic; its crystal structure consists of a single molecule located at the center of inversion symmetry. Polymorph B, on the other hand, exhibits a rather complicated two-step-like spin transition; its crystal structure consists of two symmetry-independent molecules. The crystal structure of polymorph B has been derived in the different spin states: above the high-temperature step (300 K), between the two steps (90 K), below the incomplete low-temperature step (50 K), in the light-induced metastable state (15 K), in the thermally quenched metastable state (15 K), and after relaxation from the quenched state (15 K). The correlation between the structure and magnetic properties is precisely established, allowing the complicated magnetic behavior of polymorph B to be well understood. A unique order−disorder phase transition, resulting in a modulation of the metastable state structures, is detected for the first time on such spin-transition compounds. The modulation of the structure originates from a particular ordering of the dicyanamide ligand at one of the two Fe sites.