New Electronic Structure of Quasi-One-Dimensional Halogen-Bridged Ni(III) Complexes with Strong Electron Correlations

准一维卤素桥联混价金属化合物由于表现出非常有趣的物理性质，如强的、历时的价间电荷转移带、大Stokes位移的发光、共振拉曼光谱的Overton级数、大的三阶非线性光学性质、孤立子、极化子等。在这些化合物中，铂和钯的化合物采取M(II)-M(IV)混合价态或CDW态，其中桥联的卤素从相邻两个金属离子之间的中点扭曲。另一方面，Ni化合物以Ni(III)态或SDW态为主，桥联卤素位于两个金属离子之间的中点。镍化合物的电子结构与过氧化铜超导材料的电子结构相似。然后，化合物的掺杂是非常有趣的。根据这一策略，我们用电化学…法合成了Ni-Pd混合金属配合物更多的方法。通过红外光谱、拉曼光谱、X射线光电子能谱、俄歇能谱和电子自旋共振谱研究了它们的电子结构，发现随着镍含量的增加，镍离子的氧化态为+3，而Pd(II)-Pd(IV)混合价态接近Pd(III)态。在红外光谱中，υ(N-H)在Pd(II)-Pd(IV)中的二重态逐渐向单重态转变，表明Pd(II)-Pd(IV)状态接近Pd(III)状态。在拉曼光谱中，υ(Pd(IV)-BR)的泛音强度和泛音数目随着Ni组分的增加而减小。与纯Pd(II)-Pd(IV)和Ni(III)混合物相比，Pd(II)-Pd(IV)在室温下的积分自旋极化率增加，表明Pd(II)-Pd(IV)态转变为Pd(III)态。如上所述，随着Ni(III)组分的增加，Pd(II)-Pd(IV)态受到影响并转变为Pd(III)态。这是由于镍离子的电子关联较强所致。较少

Quasi-one-dimensional halogen-bridged mixed-valence metal compounds have attracted much attention because they show very interesting physical properties such as intense and diachronic intervalence charge transfer bandsm luminescence with large Stokes shifts, overton progression of resonance Raman spectra, large third order non-linear optical properties, solitons, polarons, etc. Among these compounds, the Pt and Pd compounds take the M (II)-M (IV) mixed valence states or CDW states, where the bridging halogens are distorted from the midpoints between neighboring two metal ions. On the other hand, the Ni compounds take the Ni(III) states or SDW states, where the bridging halogens are located at the midpoints between two metal ions. The Ni compounds have the similar electronic structures to those starting materials of copperoxide supercondutors. Then, the doping to the compounds are very interesting. According such strategy, we have synthesized Ni-Pd mixed-metal complexes by electrochemic … More al methods. In order to investigate their electronic structures, we have measured IR, Raman spectra, XPS, Auger spectra and ESR spectra.The XPS and Auger spectra revealed that the oxidation states of the Ni ions is +3, but the Pd(II)-Pd(IV) mixed-valence states approach the Pd(III) states with increase of Ni components. In the IR spectra, the doublet of υ(N-H) in Pd(II)-Pd(IV) is gradually changing to the singlet, indicating that the Pd(II)-Pd(IV) state approach the Pd(III) states. In the Raman spectra, the intensity and the number of overtone of υ(Pd(IV)-Br) decrease with increase of the Ni components as observed in IR spectra. The integrated spin susceptibilities at room temperature are enhanced compared with those pure mixture of Pd(II)-Pd(IV) and Ni(III), indicating that the Pd(II)-Pd(IV) states are changed to the Pd(III) sates.As mentioned above, the Pd(II)-Pd(IV) states are influenced and changed to the Pd(III) states with increase of the Ni(III) components. This is due to the stronger electron correlation of the Ni ions. Less