温致变色和光致变色氰合金属 Fe/Co 正方形：控制电子转移温度的研究。

Thermochromic and photoresponsive cyanometalate Fe/Co squares: toward control of the electron transfer temperature.

机构信息

Department of Chemistry and Biochemistry and ⊥Center for Nanoscience, University of Missouri-St. Louis , St. Louis, Missouri 63121, United States.

出版信息

J Am Chem Soc. 2014 Dec 3;136(48):16854-64. doi: 10.1021/ja508280n. Epub 2014 Nov 19.

DOI:10.1021/ja508280n

PMID:25340715

Abstract

Two structurally related and photoresponsive cyanide-bridged Fe/Co square complexes, {Fe2Co2}, are reported: {[(Tp(Me))Fe(CN)3]2[Co(bpy)2]2[(Tp(Me))Fe(CN)3]2}·12H2O (2) and {[(Tp(Me))Fe(CN)3]2[Co(bpy)2]2[BPh4]2}·6MeCN (3), where Tp(Me) and bpy are hydridotris(3-methylpyrazol-1-yl)borate and 2,2'-bipyridine, respectively. Through electrochemical and spectroscopic studies, the Tp(Me) ligand appears to be a moderate σ donor in comparison to others in the [NEt4][(Tp(R))Fe(III)(CN)3] series [where Tp(R) = Tp, hydridotris(pyrazol-1-yl)borate; Tp(Me) = hydridotris(3-methylpyrazol-1-yl)borate; pzTp = tetrakis(pyrazol-1-yl)borate; Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate; Tp*(Me) = hydridotris(3,4,5-trimethylpyrazol-1-yl)borate]. The spectroscopic, structural, and magnetic data of the {Fe2Co2} squares indicate that thermally-induced intramolecular electron transfer reversibly converts {Fe(II)LS(μ-CN)Co(III)LS} pairs into {Fe(III)LS(μ-CN)Co(II)HS} units near ca. 230 and 244 K (T1/2) for 2 and 3, respectively (LS: low spin; HS: high spin). These experimental results show that 2 and 3 display light-induced {Fe(III)LS(μ-CN)Co(II)HS} metastable states that relax to thermodynamic {Fe(II)LS(μ-CN)Co(III)LS} ones at ca. 90 K. Ancillary Tp(R) ligand donor strength appears to be the dominant factor for tuning electron transfer properties in these {Fe2Co2} complexes.

摘要

报告了两个结构相关且光响应的氰桥联 Fe/Co 四方配合物，{Fe2Co2}：{[(Tp(Me))Fe(CN)3]2[Co(bpy)2]2[(Tp(Me))Fe(CN)3]2}·12H2O（2）和{[(Tp(Me))Fe(CN)3]2[Co(bpy)2]2[BPh4]2}·6MeCN（3），其中 Tp(Me)和 bpy 分别为氢代三(3-甲基吡唑-1-基)硼酸盐和 2,2'-联吡啶。通过电化学和光谱研究，与 [NEt4][(Tp(R))Fe(III)(CN)3] 系列中的其他配体相比，Tp(Me) 配体似乎是一个中等的 σ 给体[其中 Tp(R) = Tp，氢代三(吡唑-1-基)硼酸盐；Tp(Me) = 氢代三(3-甲基吡唑-1-基)硼酸盐；pzTp = 四(吡唑-1-基)硼酸盐；Tp* = 氢代三(3,5-二甲基吡唑-1-基)硼酸盐；Tp*(Me) = 氢代三(3,4,5-三甲基吡唑-1-基)硼酸盐]。{Fe2Co2} 四方的光谱、结构和磁性数据表明，热诱导的分子内电子转移可逆地将{Fe(II)LS(μ-CN)Co(III)LS} 对转化为{Fe(III)LS(μ-CN)Co(II)HS} 单元，在 2 和 3 中分别在约 230 和 244 K（T1/2）附近（LS：低自旋；HS：高自旋）。这些实验结果表明，2 和 3 显示出光诱导的{Fe(III)LS(μ-CN)Co(II)HS} 亚稳态，在约 90 K 时弛豫到热力学{Fe(II)LS(μ-CN)Co(III)LS} 状态。辅助 Tp(R) 配体供体强度似乎是调节这些{Fe2Co2} 配合物中电子转移性质的主要因素。