Department of Chemistry, College of Science, Rikkyo University, 3-34-1, Nishi-ikebukuro, Toshima, 171-8501 Tokyo, Japan.
Chemistry. 2012 Feb 20;18(8):2374-81. doi: 10.1002/chem.201102236. Epub 2012 Jan 16.
A bis(ruthenium-bipyridine) complex bridged by 1,8-bis(2,2':6',2''-terpyrid-4'-yl)anthracene (btpyan), Ru(2)(μ-Cl)(bpy)(2)(btpyan)(3) (1(3); bpy = 2,2'-bipyridine), was prepared. The cyclic voltammogram of 1(3) in water at pH 1.0 displayed two reversible Ru(II),Ru(II)/Ru(II),Ru(III) and Ru(II),Ru(III)/Ru(III),Ru(III) redox couples at E(1/2)(1) = +0.61 and E(1/2)(2) = +0.80 V (vs. Ag/AgCl), respectively, and an irreversible anodic peak at around E = +1.2 V followed by a strong anodic currents as a result of the oxidation of water. The controlled potential electrolysis of 1 ions at E = +1.60 V in water at pH 2.6 (buffered with H(3)PO(4)/NaH(2)PO(4)) catalytically evolved dioxygen. Immediately after the electrolysis of the 1 ion in H(2)(16)O at E = +1.40 V, the resultant solution displayed two resonance Raman bands at nu = 442 and 824 cm(-1). These bands shifted to nu = 426 and 780 cm(-1), respectively, when the same electrolysis was conducted in H(2)(18)O. The chemical oxidation of the 1 ion by using a Ce(IV) species in H(2)(16)O and H(2)(18)O also exhibited the same resonance Raman spectra. The observed isotope frequency shifts (Δnu = 16 and 44 cm(-1)) fully fit the calculated ones based on the Ru-O and O-O stretching modes, respectively. The first successful identification of the metal-O-O-metal stretching band in the oxidation of water indicates that the oxygen-oxygen bond at the stage prior to the evolution of O(2) is formed through the intramolecular coupling of two Ru-oxo groups derived from the 1 ion.
一种由 1,8-双（2,2':6',2''-三联吡啶-4'-基）蒽（btpyan）桥连的双（钌-联吡啶）配合物，[Ru(2)(μ-Cl)(bpy)(2)(btpyan)]（BF(4))(3) (1(3)；bpy = 2,2'-联吡啶)，被制备出来。在 pH 值为 1.0 的水中，1(3) 的循环伏安图显示了两个可逆的Ru(II),Ru(II)/Ru(II),Ru(III)和Ru(II),Ru(III)/Ru(III),Ru(III)氧化还原电对，E(1/2)(1) = +0.61 和 E(1/2)(2) = +0.80 V（相对于 Ag/AgCl），以及一个不可逆的阳极峰，约在 E = +1.2 V 左右，随后由于水的氧化而产生强烈的阳极电流。在 pH 值为 2.6 的水中（用 H(3)PO(4)/NaH(2)PO(4)缓冲），在 E = +1.60 V 下对1离子进行恒电位电解，催化产生氧气。在 E = +1.40 V 下对1离子在 H(2)(16)O 中的电解立即完成后，所得溶液在 nu = 442 和 824 cm(-1)处显示两个共振拉曼带。当在 H(2)(18)O 中进行相同的电解时，这些带分别移动到 nu = 426 和 780 cm(-1)。使用 Ce(IV)物种在 H(2)(16)O 和 H(2)(18)O 中对1离子的化学氧化也表现出相同的共振拉曼光谱。观察到的同位素频率位移（Δnu = 16 和 44 cm(-1))完全符合基于 Ru-O 和 O-O 伸缩模式的计算值。在水中氧化过程中首次成功识别金属-O-O-金属伸缩带表明，在 O(2)产生之前的阶段，氧氧键是通过源自1离子的两个 Ru-氧基团的分子内偶联形成的。
