Zinc 1s Valence-to-Core X-ray Emission Spectroscopy of Halozincate Complexes.
Zinc 1s Valence-to-Core X-ray Emission Spectroscopy of Halozincate Complexes.
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DOI：
10.1021/acs.jpca.9b08037
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发表时间：
2019-10
期刊：
影响因子：
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通讯作者：
Coby J. Clarke;S. Hayama;Alexander Hawes;J. Hallett;T. Chamberlain;K. Lovelock;N. Besley
中科院分区：
文献类型：
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作者：
Coby J. Clarke;S. Hayama;Alexander Hawes;J. Hallett;T. Chamberlain;K. Lovelock;N. Besley
用含时密度泛函理论(TDDFT)方法对六种离子液体的Zn1s价核(VTC)X射线发射光谱进行了实验测量和模拟计算。将[C8C1Im]X和Zn(II)X2按不同摩尔分数(0.33、0.50和0.67)按X=Cl或Br3种摩尔分数混合制得7种离子液体，再将[P6，6，6，14]Cl和摩尔分数为0.33的ZnCl2混合制成离子液体。对[ZZX4]2-、[ZZX6]2-和[ZZ4X10]2-离子进行了计算，以捕获预期的金属络合物形态。VTC发射光谱显示三个单电子过程谱带可归属于配体p型轨道、锌d型轨道和配体S型轨道的发射。对于所有7种离子液体，最高占据分子轨道都来自配体p轨道，对于同一X，不同大小的金属络合物的光谱在相对峰强度和峰能量方面都非常相似。无论是实验还是TDDFT计算，对于配体S和p轨道，氯基和溴基金属络合物之间的能量差为0.5 eV，而锌的3d轨道能量相对不受配体的同一性的影响。TDDFT计算发现，对于具有对称等价锌原子的离子([Zn2X6]2-和[Zn4X10]2-)，最合适的核-电离参考态是位于单个锌原子上的核-空穴。在这个框架中，较大离子的光谱可以看作是只有一个锌原子的四面体配合物的光谱之和，配位配体的结构变化很小。由于光谱对配体几何结构的微小变化相对不敏感，这与在实验中测量的光谱的微小变化是一致的。
The Zn 1s valence-to-core (VtC) X-ray emission spectra of six ionic liquids have been measured experimentally and simulated based upon time-dependent density-functional theory (TDDFT) calculations. The seven ionic liquids were made by mixing [C8C1Im]X and Zn(II)X2 at three different ZnX2 mole fractions (0.33, 0.50 or 0.67) for X=Cl or Br, and a further ionic liquid was made by mixing [P6,6,6,14]Cl and a mole fraction of ZnCl2 of 0.33. Calculations were performed for the [ZnX4]2-, [Zn2X6]2- and [Zn4X10]2- ions to capture the expected metal complex speciation. The VtC emission spectra showed three bands arising from single electron processes that can be assigned to emission from ligand p-type orbitals, zinc d orbitals and ligand s-type orbitals. For all seven ionic liquids, the highest occupied molecular orbital arises from the ligand p orbitals, and the spectra for the different size metal complexes for the same X were found to be very similar, in terms of both relative peak intensities and peak energies. For both experiments and TDDFT calculations, there was an energy difference of 0.5 eV between the Cl-based and Br-based metal complexes for the ligand s and p orbitals, while the Zn 3d orbital energies were relatively unaffected by the identity of the ligand. The TDDFT calculations find that for the ions with symmetrically equivalent zinc atoms ([Zn2X6]2- and [Zn4X10]2-), the most appropriate core-ionised reference state has a core-hole that is localised on a single zinc atom. In this framework, the spectra for the larger ions can be viewed as a sum of spectra for the tetrahedral complex with a single zinc atom with small variations in the structure of the coordinating ligands. Since the spectra are relatively insensitive to small changes in the geometry of the ligands, this is consistent with the small variation in the spectra measured in experiment.