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• 作者：Mari Sasaki ; Hashen Wu ; Daisuke Kawakami ; Shinya Takaishi ; Takashi Kajiwara ; Hitoshi Miyasaka ; Brian K. Breedlove ; Masahiro Yamashita ; Hideo Kishida ; Hiroyuki Matsuzaki ; Hiroshi Okamoto ; Hisaaki Tanak
• 刊名：Inorganic Chemistry
• 出版年：2009
• 出版时间：August 3, 2009
• 年：2009
• 卷：48
• 期：15
• 页码：7446-7451
• 全文大小：864K
• 年卷期：v.48,no.15(August 3, 2009)
• ISSN：1520-510X

文摘

Single crystals of quasi-one-dimensional bromo-bridged Ni−Pd mixed-metal complexes with 2S,3S-diaminobutane (bn) as an in-plane ligand, [Ni_1−xPd_x(bn)₂Br]Br₂, were obtained by using an electrochemical oxidation method involving mixed methanol/2-propanol (1:1) solutions containing different ratios of [Ni^II(bn)₂]Br₂ and [Pd^II(bn)₂]Br₂. To investigate the competition between the electron-correlation of the Ni^III states, or Mott-Hubbard states (MH), and the electron−phonon interaction of the Pd^II−Pd^IV mixed valence states, or charge-density-wave states (CDW), in the Ni−Pd mixed-metal compounds, X-ray structure analyses, X-ray oscillation photograph, and Raman, IR, ESR, and single-crystal reflectance spectra were analyzed. In addition, the local electronic structures of Ni−Pd mixed-metal single crystals were directly investigated by using scanning tunneling microscopy (STM) at room temperature and ambient pressure. The oxidation states of [Ni_1−xPd_x(bn)₂Br]Br₂ changed from a M^II−M^IV mixed valence state to a M^III MH state at a critical mixing ratio (x_c) of 0.8, which is lower than that of [Ni_1−xPd_x(chxn)₂Br]Br₂ (chxn = 1R,2R-diaminocyclohexane) (x_c ≈ 0.9) reported previously. The lower value of x_c for [Ni_1−xPd_x(bn)₂Br]Br₂ can be explained by the difference in their CDW dimensionalities because the three-dimensional CDW ordering in [Pd(bn)₂Br]Br₂ observed by using X-ray diffuse scattering stabilizes the Pd^II−Pd^IV mixed valence state more than two-dimensional CDW ordering in [Pd(chxn)₂Br]Br₂ does, which has been reported previously.