Probes of Superexchange Influence in Creutz-Taube ion Likely Complexes

• Main Authors: Chun-Jheng Wang, 王淳正
• Other Authors: Yuan-Jang Chen
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/58178538303420304770

碩士 === 輔仁大學 === 化學系 === 96 === We used 2,3-di(2-pyridyl)pyrazine, 2,3-dpp, and 2,5-di(2-pyridyl) -pyrazine, 2,5-dpp, as bridging ligand in the series of [{Ru(NH3)4}2(dpp)]5+ complexes to discussing the strong coupling between the metal-to-ligand charge-transfer (MLCT) excited-states and ground-state. In electrochemical work, the difference between E1/2(Ru(1)III/II) and E1/2(Ru(2)III/II) is 416 mV for [{Ru(NH3)4}2 -(2,3-dpp)]4+ and 428 mV for [{Ru(NH3)4}2(2,5-dpp)]4+ .The comproportionation constant (GC) for both complexes are around 3000 cm-1. The figure of the GC vs. the E-1, which the E is the energy difference between HOMO and LUMO, exhibits strong coupling between ground state and excited-state. In the absorption spectra, the metal-to-metal charge-transfer (MMCT) absorption is about 6410 cm-1 for [{Ru(NH3)4}2(2,5-dpp)]5+ and 6390 cm-1 for [{Ru(NH3)4}2(2,3-dpp)]5+, and the each max is 3140 M-1cm-1 and 2500 M-1cm-1. The MMCT energies of Creutz-Taube ion locates in 6400 cm-1, which is aimilar to our complexes. However the max of Creutz-Taube ion is about 5000 M-1cm-1. The MMCT intensity of our targets complexes, [{Ru(NH3)4}2(dpp)]5+ , show a half intensity, which is comparing to Creutz-Taube ion. The phenomenon of the d5/d6 coupling between terminal metal ions for [{Ru(NH3)4}2(dpp)]5+ series is very different than the Creutz-Taube ion.