名称:
                                Reversible Bond Formation and Cleavage of the Oxo Bridge of [Ru
            2
            (μ‐O)(dioxolene)
            2
            (btpyxa)]
            3+
            [btpyxa = 2,7‐Di‐
            tert
            ‐butyl‐9,9‐dimethyl‐4,5‐bis(2,2′:6′,2′′‐terpyrid‐4′‐yl)xanthene] Driven by a Three‐Electron Redox Reaction
                             
                            
                                摘要:
                                AbstractThe bis(chlororuthenium) complex [Ru2Cl2(3,6‐tBu2sq)2(btpyxa)](PF6)2 [1](PF6)2 [3,6‐tBu2sq = 3,6‐di‐tert‐butyl‐1,2‐benzosemiquinone; btpyxa = 2,7‐di‐tert‐butyl‐9,9‐dimethyl‐4,5‐bis(2,2′:6′,2′′‐terpyrid‐4′‐yl)xanthene] and the oxo‐bridged diruthenium complex [Ru2(μ‐O)(3,6‐tBu2sq)2(btpyxa)](PF6)3 [2](PF6)3 were synthesized, and the redox behavior of these complexes, which contain a non‐innocent dioxolene ligand, was investigated by electrochemical and electrospectrochemical methods. Dicationic [1]2+ undergoes two successive metal‐centered one‐electron and a simultaneous two‐electron ligand‐based redox reaction at E1/2 = +0.13 and +0.09 and E1/2 = –0.75 V (vs. SCE), respectively, in CH2Cl2. The UV/Vis/NIR spectrum of tricationic [2]3+ shows an intervalence‐transition (IT) band at 1333 nm (ϵ = 1.52 × 104 M–1 cm–1) in a near‐IR region together with two CT bands at 766 (ϵ = 2.21 × 104 M–1 cm–1) and 586 nm (ϵ = 1.13 × 104 M–1 cm–1) in CH2Cl2. The mixed‐valence complex of [2]3+ with an RuIV–O–RuIII core is reversibly oxidized and reduced to the RuIV–RuIV and RuIII–RuIII oxidation states at E1/2 = +0.63 and –0.01 V, respectively, in CH2Cl2. On the other hand, three‐electron reduction of [2](PF6)3 is accompanied by the cleavage of the Ru–O–Ru bond at Ep = +0.02 V to give [{Ru(OMe)(3,5‐tBu2sq)}{Ru(OH2)(3,5‐tBu2sq)}(btpyxa)]+ in MeOH. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)