Crystal Structure, Magnetic Properties, and 57Fe Mössbauer Spectroscopy of the Two-Dimensional Coordination Polymers [M(1,2-bis(1,2,4-triazol-4-yl)ethane)2(NCS)2]
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- 作者：Yann Garcia ; Georges Bravic ; Christine Gieck ; Daniel Chasseau ; Wolfgang Tremel ; and Philipp Gü ; tlich
- 刊名：Inorganic Chemistry
- 出版年：2005
- 出版时间：December 26, 2005
- 年：2005
- 卷：44
- 期：26
- 页码：Gütlich
- 全文大小：186K
- 年卷期：v.44,no.26(December 26, 2005)
- ISSN：1520-510X
文摘
New coordination polymers of the formula [M(btre)2(NCS)2] (btre = 1,2-bis(1,2,4-triazol-4-yl)ethane; MII = Fe, Co)have been synthesized, and their crystal structures have been determined at 293 K by X-ray analysis. The FeIIcompound (C7H8FeN7S2) crystallizes in the monoclinic space group P21/n, a = 12.439(5) Å, b = 8.941(2) Å, c =9.321(3) Å, 
ges/gifchars/beta2.gif" BORDER=0 ALIGN="middle"> = 90.88(2)ges/entities/deg.gif">, V = 1036.6(6) Å3, Z = 2, 3791 reflections [I > 3ges/gifchars/sigma.gif" BORDER=0 >(I)], RF = 0.036, wR2 = 0.123. TheCoII compound is isostructural to the FeII compound. The crystal structure consists of a 2D sheet in which themetal ions are linked by bis monodentate (N1, N1') 1,2,4-triazole ligands. The structure is stabilized by ges/gifchars/pi.gif" BORDER=0 >-bondinteractions between two adjacent sheets and by S···S interactions. Temperature-dependent SQUID, 57Fe Mössbauer,and X-ray diffraction measurements indicate that [Fe(btre)2(NCS)2] retains a HS ground state upon cooling from293 K down to 8 K. The surprising absence of spin-crossover behavior for this Fe(II)-1,2,4-triazole polymericcoordination compound that has been confirmed by pressure experiments up to ~12 kbar and by light irradiationexperiments at 10 K is discussed on the basis of its structural features. Insight into the origin of the cooperativeeffects of the spin transition in [Fe(btr)2(NCS)2]·H2O (btr = 4,4'-bis-1,2,4-triazole) is also given thanks to a re-evaluation of its distortion parameters in the high- and low-spin states.