Mixed-Valence Properties of Square [Ru4] 5+,6+

• Main Authors: Sheng-Yi Huang, 黃勝義
• Other Authors: Keh Shin Kwan
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/51440606867741710790

碩士 === 輔仁大學 === 化學系 === 95 === The ruthenium complexes ([Ru(bpy)2(CN)2], [Ru(bpy)2(CH3CN)2]2+ and square [Ru4]4+) were synthesized and studied the electrochemical and spectral properties. We also tried to focused the mixed-vlaence behavior of [Ru4]5+ on CNS model (Creutz-Newton-Sutin model). In electrochemical work, E1/2(RuIII/II) at 0.86V and 1.48V for [Ru(bpy)2(CN)2] and [Ru(bpy)2(CH3CN)2]2+, respectively. [Ru4]8+/7+/6+/5+/4+ showed four reversible peaks at 0.71, 0.93, 1.71 and 1.98V (vs. Ag/AgCl), first couple is E1/2(Ru(C)III/II) redox waves and second couple is E1/2(Ru(N)III/II) redox waves which correspond to the four one-electron redox processes of [RuCIII-RuNIII-RuCIII-RuNIII]+8↔[RuCIII-RuNIII-RuCIII-RuNII]+7↔[RuCIII-RuNII-RuCIII-RuNII]+6↔[RuCIII-RuNII-RuCII-RuNII]+5↔[RuCII-RuNII-RuCII-RuNII]+4. In time scalair absorption spectra, titrating with Ce4+ tended [Ru4]4+ → [Ru4]5+, found two metal-to-metal charge-transfer (MMCT) absorptions at 7470 cm-1(εmax = 9620 M-1cm-1) and 11600 cm-1(εmax = 3380 M-1cm-1), respectively, and [Ru4]5+ → [Ru4]6+ at 10000 cm-1 (εmax = 23000 M-1cm-1). The matrix element (Hab) between neighbor RuIII(C) and RuII(N), and the degrees of electronic delocalization (α2) were estimated to be 2010 cm-1, 1470 cm-1 and 0.065, 0.016 for the [Ru4]+5 state and 3480 cm-1 and 0.12 for the [Ru4]+6 state. Finally, the very strong coupling between neighbor RuIII_RuII couple give possible interaction between diagonal RuIII_RuII couple.