铁（II）-2-吡啶基[1,2,3]三唑并[1,5-a]吡啶体系中的自旋交叉行为：X射线结构、量热、磁性和光磁研究。

Spin crossover behavior in the iron(II)-2-pyridyl[1,2,3]triazolo[1,5-a]pyridine system: X-ray structure, calorimetric, magnetic, and photomagnetic studies.

作者信息

Niel Virginie, Gaspar Ana B, Muñoz M Carmen, Abarca Belén, Ballesteros Rafael, Real José Antonio

机构信息

Institut de Ciencia Molecular/Departament de Química Inorgánica, Universitat de València, Doctor Moliner 50, 46100 Burjassot, Spain.

出版信息

Inorg Chem. 2003 Jul 28;42(15):4782-8. doi: 10.1021/ic034366z.

DOI:10.1021/ic034366z

PMID:12870971

Abstract

Compounds Fe(tzpy)(3)(2) (1), [Fe(tzpy)(2)(NCS)(2)].S (S = 2CHCl(3) (2), H(2)O (3)), and [Fe(tzpy)(2)(NCSe)(2)] (4) (tzpy is 3-(2-pyridyl)[1,2,3]triazolo[1,5-a]pyridine) have been synthesized and characterized. 1 crystallizes in the monoclinic noncentrosymmetric system, Cc space group, Z = 4, with a = 11.4680(6) A, b = 27.449(2) A, c = 12.4510(8) A, beta = 108.860(5) degrees, V = 3709.0(4) A(3), and T = 293(2) K. The structure consists of mononuclear Fe(tzpy)(3) diamagnetic species, which stack via pi-interactions. Disordered BF(4)(-) anions fill the voids generated by complex cations. 2 crystallizes in the triclinic system, P one macro space group, Z = 1, with a = 8.3340(4) A, b = 8.6520(4) A, c = 11.6890(6) A, alpha = 89.113(2) degrees, beta = 81.612(2) degrees, gamma = 77.803(2) degrees, V = 814.90(7) A(3), and T = 293(2) K. The structure consists of mononuclear [Fe(tzpy)(2)(NCS)(2)] neutral species, which interact each other via pi-staking defining layers separated by two-dimensional arrays of CHCl(3). The average Fe-N bond distance, 2.176(3) A, corresponds to what is expected for an iron(II) ion in the high-spin state. Compounds 2-4 undergo thermal-driven spin conversion. The regular solution model was applied to account for the corresponding to thermodynamic parameters. The intermolecular interaction parameter, the characteristic temperature, and the enthalpy and entropy changes associated with the spin conversion were estimated as Gamma = 0.86 (2), 0.89 (3), and 3.79 (4) kJ mol(-1), T(1/2) = 75 (2), 118 (3), and 251 K (4), Delta H = 3.67 (2) and 4.08 (3) kJ mol(-1), and Delta S = 34 (2) and 34.5 (3) J K(-1) mol(-1). Delta H = 8.75 kJ mol(-1) and Delta S = 34.8 J K(-1) mol(-1) were estimated from calorimetric measurements and used as fixed parameters for 4. A quantitative light-induced excited spin state trapping (LIESST) effect was observed for 3, and the high-spin to low-spin relaxation was studied in the temperature region 20-63 K.

摘要

已合成并表征了化合物Fe(tzpy)(3)(2) (1)、[Fe(tzpy)(2)(NCS)(2)].S（S = 2CHCl(3) (2)、H(2)O (3)）和[Fe(tzpy)(2)(NCSe)(2)] (4)（tzpy为3-(2-吡啶基)[1,2,3]三唑并[1,5-a]吡啶）。1在单斜非中心对称体系Cc空间群中结晶，Z = 4，a = 11.4680(6) Å，b = 27.449(2) Å，c = 12.4510(8) Å，β = 108.860(5)°，V = 3709.0(4) Å(3)，T = 293(2) K。该结构由单核Fe(tzpy)(3)抗磁物种组成，通过π相互作用堆叠。无序的BF(4)(-)阴离子填充由络合阳离子产生的空隙。2在三斜体系P 1宏观空间群中结晶，Z = 1，a = 8.3340(4) Å，b = 8.6520(4) Å，c = 11.6890(6) Å，α = 89.113(2)°，β = 81.612(2)°，γ = 77.803(2)°，V = 814.90(7) Å(3)，T = 293(2) K。该结构由单核[Fe(tzpy)(2)(NCS)(2)]中性物种组成，它们通过π堆积相互作用，形成由CHCl(3)二维阵列隔开的层。平均Fe-N键长为2.176(3) Å，与高自旋态铁(II)离子的预期值相符。化合物2 - 4发生热驱动自旋转变。应用正则溶液模型来解释相应的热力学参数。估计分子间相互作用参数、特征温度以及与自旋转变相关的焓变和熵变为：γ = 0.86 (2)、0.89 (3)和3.79 (4) kJ mol(-1)，T(1/2) = 75 (2)、118 (3)和251 K (4)，ΔH = 3.67 (2)和4.08 (3) kJ mol(-1)，以及ΔS = 34 (2)和34.5 (3) J K(-1) mol(-1)。通过量热测量估计ΔH = 8.75 kJ mol(-1)和ΔS = 34.8 J K(-1) mol(-1)，并将其用作4的固定参数。对3观察到了定量的光诱导激发自旋态捕获(LIESST)效应，并在20 - 63 K温度范围内研究了高自旋到低自旋的弛豫。