Redox Behavior of Rhodium 9,10-Phenanthrenediimine Complexes

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• 作者：David W. Shaffer ; Scott A. Ryken ; Ryan A. Zarkesh ; Alan F. Heyduk
• 刊名：Inorganic Chemistry
• 出版年：2011
• 出版时间：January 3, 2011
• 年：2011
• 卷：50
• 期：1
• 页码：13-21
• 全文大小：924K
• 年卷期：v.50,no.1(January 3, 2011)
• ISSN：1520-510X

文摘

New square-planar rhodium complexes of the redox-active ligand 9,10-phenenthrenediimine (phdi) have been prepared and studied. The complexes [dpp-nacnac^CH3]Rh(phdi) (2a; [dpp-nacnac^CH3]^{鈭?/sup> = CH[C(Me)(N-iPr₂C₆H₃)]₂鈭?/sup>) and [dpp-nacnacCF3]Rh(phdi) (2b; [dpp-nacnacCF3]鈭?/sup> = CH[C(CF₃)(N-iPr₂C₆H₃)]₂鈭?/sup>) have been prepared from the corresponding [nacnac]Rh(CO)₂ synthons by treatment with Me₃NO in the presence of the phdi ligand. Complexes 2a and 2b are diamagnetic, and their absorption spectra are dominated by intense charge-transfer transitions throughout the visible region. Electrochemical studies indicate that both the phdi ligand and the rhodium metal center are redox-active, with the [nacnac]鈭?/sup> ligands serving to modulate the one-electron-oxidation and -reduction redox potentials. In the case of 2a, chemical oxidation and reduction reactions provided access to the one-electron-oxidized cation, [2a]+, and one-electron-reduced anion, [2a]鈭?/sup>, the latter of which has been characterized in the solid state by single-crystal X-ray diffraction. Solution electron paramagnetic resonance spectra of [2a]+ and [2a]鈭?/sup> are consistent with S = 1/₂ spin systems, but surprisingly the low-temperature spectrum of [2a]鈭?/sup> shows a high degree of rhombicity, suggestive of rhodium(II) character in the reduced anion.}