Charge and Spin-State Characterization of Cobalt Bis(o-dioxolene) Valence Tautomers Using Co Kβ X-ray Emission and L-Edge X-ray Absorption Spectroscopies
Charge and Spin-State Characterization of Cobalt Bis(o-dioxolene) Valence Tautomers Using Co Kβ X-ray Emission and L-Edge X-ray Absorption Spectroscopies
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DOI：
10.1021/acs.inorgchem.6b01666
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发表时间：
2017-01-16
影响因子：
4.6
通讯作者：
Gaffney, Kelly J.
中科院分区：
文献类型：
--
作者：
Liang, H. Winnie;Kroll, Thomas;Gaffney, Kelly J.
Co(phen)-(3,5- dbq)(2)和Co(tmeda)(3,5- dbq)(2)的价互变异构体，其中3,5- dbq是3,5-二叔丁基-1,2-苯醌的半醌（SQ(-)）或儿茶酚酸（Cat(2-)）形式，已经通过一系列钴特异性x射线光谱进行了检查。在这项工作中，我们利用133p x射线发射光谱（K β XES）对三维过渡金属离子的氧化和自旋态的灵敏度来确定价态互变异构体的钴特异性电子结构。将它们的K β x光谱与已知氧化态和自旋态的钴配位配合物的光谱进行比较表明，低温价态互变异构体可描述为低自旋Co-III构型，高温价态互变异构体可描述为高自旋Co-II构型。高温价态互变体的L-edge x射线吸收光谱（L-edge XAS）和K β x射线吸收光谱和L-edge XAS光谱的配体场原子多重计算进一步支持了这一结论。根据K β x测量的Co位有效自旋和磁化率测量的分子自旋矩，讨论了钴价互变体中钴中心与SQ（-）之间磁交换相互作用的性质和强度。
The valence tautomeric stated of Co(phen)-(3,5-DBQ)(2) and co(tmeda)(3,5-DBQ)(2), where 3,5-DBQ is either the semiquinone (SQ(-)) or catecholate (Cat(2-)) form of 3,5-di-tert-butyl-1,2-benzoquinone, have been examined by a series of cobalt-specific X-ray spectroscopies. In this work, we have utilized the sensitivity of 1s3p X-ray emission Spectroscopy (K beta XES) to the oxidation and spin states of 3d transition-metal ions to determine the cobalt-specific electronic structure of valence tautomers. A comparison of their K beta XES spectra with the spectra of cobalt coordination complexes with known oxidation and spin states demonstrates that the low-temperature valence tautomer can be described as a low-spin Co-III configuration and the high-temperature valence tautomer as a high-spin Co-II configuration. This conclusion is further supported by L-edge X-ray absorption spectroscopy (L-edge XAS) of the high-temperature Valence tautomers and ligand-field atomic-multiplet calculations of the K beta XES and L-edge XAS spectra. The nature and strength of the magnetic exchange interaction between the cobalt center and SQ(-) in cobalt valence tautomers is discussed: in view of the effective spin at the Co site from K beta XES and the molecular spin moment from magnetic susceptibility measurements.