Chuang Yu Chun, Sheu Chou Fu, Lee Gene Hsiang, Chen Yu Sheng, Wang Yu
Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan.
Instrumentation Center, National Taiwan University, Taipei 10617, Taiwan.
Acta Crystallogr B Struct Sci Cryst Eng Mater. 2017 Aug 1;73(Pt 4):634-642. doi: 10.1107/S2052520617007119. Epub 2017 Jul 25.
High-resolution X-ray diffraction experiments and atom-specific X-ray absorption experiments are applied to investigate a series of square planar complexes with the non-innocent ligand of maleonitriledithiolate (mnt), [SC(CN)], containing M-S bonds. Four complexes of (PyH)[M(mnt)], where M = Ni or Cu, z = 2 or 1 and PyH = CNH, were studied in order to clarify whether such one-electron oxidation-reduction, [M(mnt)]/[M(mnt)], is taking place at the metal or the ligand site. Combining the techniques of metal K-, L-edge and S K-edge X-ray absorption spectroscopy with high-resolution X-ray charge density studies, it is unambiguously demonstrated that the electron redox reaction is ligand based and metal based for Ni and Cu pairs, respectively. The bonding characters in terms of topological properties associated with the bond critical points are compared between the oxidized form [ML] and the reduced form [ML]. In the case of Ni complexes, the formal oxidation state of Ni remains as Ni and each mnt ligand carries a 2- charge in [Ni(mnt)], but only one of the ligands is formally oxidized in [Ni(mnt)]. In contrast, in the case of Cu complexes, the mnt remains as 2- in both complexes, but the formal oxidation states of the metal are Cu and Cu. Bond characterizations and d-orbital populations will be presented. The complementary results of XAS, XRD and DFT calculations will be discussed. The conclusion on the redox reactions in these complexes can be firmly established.
应用高分辨率X射线衍射实验和原子特异性X射线吸收实验来研究一系列含有M-S键、带有马来二腈二硫醇盐（mnt）[SC(CN)]这种非无辜配体的平面正方形配合物。研究了四种（PyH）[M(mnt)]配合物，其中M = Ni或Cu，z = 2或1且PyH = CNH，以阐明这种单电子氧化还原反应，即[M(mnt)]/[M(mnt)]，是在金属位点还是配体位点发生。将金属K边、L边和S K边X射线吸收光谱技术与高分辨率X射线电荷密度研究相结合，明确证明了电子氧化还原反应分别基于配体和基于金属，对应Ni和Cu对。比较了氧化形式[ML]和还原形式[ML]之间与键临界点相关的拓扑性质方面的键合特征。对于Ni配合物，Ni的形式氧化态保持为Ni，并且在[Ni(mnt)]中每个mnt配体带有2-电荷，但在[Ni(mnt)]中只有一个配体被正式氧化。相反，对于Cu配合物，mnt在两种配合物中都保持为2-，但金属的形式氧化态分别为Cu和Cu。将展示键合特征和d轨道占据情况。将讨论XAS、XRD和DFT计算的互补结果。可以牢固地得出这些配合物中氧化还原反应的结论。
