Kobayashi Katsuaki, Ohtsu Hideki, Wada Tohru, Kato Tatsuhisa, Tanaka Koji
Institute for Molecular Science, Department of Structural Molecular Science, CREST, Japan Science and Technology Corporation, The Graduate University for Advanced Studies, 38 Nishigonaka, Myodaiji, Okazaki, Aichi 444-8585, Japan.
J Am Chem Soc. 2003 Jun 4;125(22):6729-39. doi: 10.1021/ja0211510.
The ruthenium oxyl radical complex, [Ru(II)(trpy)(Bu(2)SQ)O(.-)] (trpy = 2,2':6',2"-terpyridine, Bu(2)SQ = 3,5-di-tert-butyl-1,2-benzosemiquinone) was prepared for the first time by the double deprotonation of the aqua ligand of Ru(III)(trpy)(Bu(2)SQ)(OH(2))(2). Ru(III)(trpy)(Bu(2)SQ)(OH(2))(2) is reversibly converted to Ru(III)(trpy)(Bu(2)SQ)(OH-) upon dissociation of the aqua proton (pK(a) 5.5). Deprotonation of the hydroxo proton gave rise to intramolecular electron transfer from the resultant O(2-) to Ru-dioxolene. The resultant [Ru(II)(trpy)(Bu(2)SQ)O(.-)] showed antiferromagnetic behavior with a Ru(II)-semiquinone moiety and oxyl radical, the latter of which was characterized by a spin trapping technique. The most characteristic structural feature of [Ru(II)(trpy)(Bu(2)SQ)O(.-)] is a long Ru-O bond length (2.042(6) A) as the first terminal metal-O bond with a single bond length. To elucidate the substituent effect of a quinone ligand, Ru(III)(trpy)(4ClSQ)(OH(2))(2) (4ClSQ = 4-chloro-1,2-benzosemiquinone) was prepared and we compared the deprotonation behavior of the aqua ligand with that of Ru(III)(trpy)(Bu(2)SQ)(OH(2))(2). Deprotonation of the aqua ligand of Ru(III)(trpy)(4ClSQ)(OH(2))(2) induced intramolecular electron transfer from OH- to the [Ru(III)(4ClSQ)] moiety affording [Ru(II)(trpy)(4ClSQ)(OH.)]+, which then probably changed to [Ru(II)(trpy)(4ClSQ)O(.-)]. The antiferromagnetic interactions (J values) between Ru(II)-semiquinone and the oxyl radical for [Ru(II)(trpy)(Bu(2)SQ)O(.-)] and for [Ru(II)(trpy)(4ClSQ)O(.-)] were 2J = -0.67 cm(-1) and -1.97 cm(-1), respectively.
钌氧基自由基配合物Ru(II)(三联吡啶)(二叔丁基苯并半醌氧基)]，trpy = 2,2':6',2"-三联吡啶，Bu(2)SQ = 3,5 - 二叔丁基 - 1,2 - 苯并半醌)首次通过Ru(III)(trpy)(Bu(2)SQ)(H₂O)₂水配体的双去质子化反应制备得到。Ru(III)(trpy)(Bu(2)SQ)(H₂O)₂在水合质子解离时(pKa 5.5)可逆地转化为[Ru(III)(trpy)(Bu(2)SQ)(OH⁻)]⁺。羟基质子的去质子化导致分子内电子从生成的O²⁻转移到Ru - 二氧杂环戊二烯。生成的[Ru(II)(trpy)(Bu(2)SQ)O(.-)]表现出反铁磁行为，具有Ru(II) - 半醌部分和氧基自由基，后者通过自旋捕获技术进行了表征。[Ru(II)(trpy)(Bu(2)SQ)O(.-)]最具特征的结构特征是作为第一个具有单键长度的末端金属 - O键的长Ru - O键长(2.042(6) Å)。为了阐明醌配体的取代基效应，制备了Ru(III)(trpy)(4ClSQ)(H₂O)₂(4ClSQ = 4 - 氯 - 1,2 - 苯并半醌)，并将其水配体的去质子化行为与Ru(III)(trpy)(Bu(2)SQ)(H₂O)₂的进行了比较。Ru(III)(trpy)(4ClSQ)(H₂O)₂水配体的去质子化诱导分子内电子从OH⁻转移到[Ru(III)(4ClSQ)]部分，得到[Ru(II)(trpy)(4ClSQ)(OH.)]⁺，然后其可能转变为[Ru(II)(trpy)(4ClSQ)O(.-)]。[Ru(II)(trpy)(Bu(2)SQ)O(.-)]和[Ru(II)(trpy)(4ClSQ)O(.-)]中Ru(II) - 半醌与氧基自由基之间的反铁磁相互作用(J值)分别为2J = -0.67 cm⁻¹和 - 1.97 cm⁻¹。
