Kosaka Wataru, Itoh Masahisa, Miyasaka Hitoshi
Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
Dalton Trans. 2015 May 7;44(17):8156-68. doi: 10.1039/c5dt00505a.
A series of paddlewheel diruthenium(ii, ii) complexes with various chlorine-substituted benzoate ligands (Cl-series) was synthesized as tetrahydrofuran (THF) adducts [Ru2(ClxPhCO2)4(THF)2]; where ClxPhCO2(-) = o-chlorobenzoate, ; m-chlorobenzoate, ; p-chlorobenzoate, ; 2,3-dichlorobenzoate, ; 2,4-dichlorobenzoate, ; 2,5-dichlorobenzoate, ; 2,6-dichlorobenzoate, ; 3,4-dichlorobenzoate, ; 3,5-dichlorobenzoate, ; 2,3,4-trichlorobenzoate, ; 2,3,5-trichlorobenzoate, ; 2,4,5-trichlorobenzoate, ; 3,4,5-trichlorobenzoate, ; 2,3,4,5-tetrachlorobenzoate, . This Cl-series and the previously synthesized F-series together with four new fluorine-substituted derivatives, [Ru2(FxPhCO2)4(THF)2] (where FxPhCO2(-) = 2,3-difluorobenzoate, ; 2,4-difluorobenzoate, ; 2,5-difluorobenzoate, ; 2,3,5-trifluorobenzoate, ), were experimentally characterized with respect to solid-state structure, magnetic properties and electrochemistry. By tuning the substituents of the benzoate ligands using chlorine or fluorine atoms, the redox potential (E1/2) for [Ru2(II,II)]/Ru2(II,III) varied over a wide range of potentials from -40 mV to 360 mV (vs. Ag/Ag(+) in THF). This was dependent on (i) the number of ortho-substituents, i.e. non-, mono- and di-o-substituted groups, with quasi-Hammett parameters for ortho-Cl and -F substitutions (σo = -0.272 and -0.217, respectively) and (ii) the general Hammett constants, σm and σp, for each group. The HOMO energy level calculated on the basis of the atomic coordinates of the solid-state structure was strongly affected by Cl- and F-substitutions as well as the redox potential in solution, which emphasizes the steric contribution of ortho-substituents in the energy level giving a deviation of EHOMO < 0.3 eV and <0.55 eV for the Cl- and F-series, respectively.
合成了一系列带有各种氯取代苯甲酸酯配体的桨轮二钌（II, II）配合物（Cl系列），以四氢呋喃（THF）加合物[Ru2(ClxPhCO2)4(THF)2]的形式存在；其中ClxPhCO2(-) = 邻氯苯甲酸酯、间氯苯甲酸酯、对氯苯甲酸酯、2,3 - 二氯苯甲酸酯、2,4 - 二氯苯甲酸酯、2,5 - 二氯苯甲酸酯、2,6 - 二氯苯甲酸酯、3,4 - 二氯苯甲酸酯、3,5 - 二氯苯甲酸酯、2,3,4 - 三氯苯甲酸酯、2,3,5 - 三氯苯甲酸酯、2,4,5 - 三氯苯甲酸酯、3,4,5 - 三氯苯甲酸酯、2,3,4,5 - 四氯苯甲酸酯。该Cl系列与先前合成的F系列以及四种新的氟取代衍生物[Ru2(FxPhCO2)4(THF)2]（其中FxPhCO2(-) = 2,3 - 二氟苯甲酸酯、2,4 - 二氟苯甲酸酯、2,5 - 二氟苯甲酸酯、2,3,5 - 三氟苯甲酸酯），在固态结构、磁性和电化学方面进行了实验表征。通过使用氯或氟原子调节苯甲酸酯配体的取代基，[Ru2(II,II)]/Ru2(II,III)的氧化还原电位（E1/2）在 - 40 mV至360 mV的宽电位范围内变化（相对于THF中的Ag/Ag(+)）。这取决于（i）邻位取代基的数量，即无、单和二邻位取代基，邻位Cl和 - F取代的准哈米特参数（分别为σo = - 0.272和 - 0.217），以及（ii）每个基团的一般哈米特常数σm和σp。基于固态结构的原子坐标计算的HOMO能级受到Cl - 和F - 取代以及溶液中氧化还原电位的强烈影响，这强调了邻位取代基在能级中的空间贡献，对于Cl系列和F系列，EHOMO的偏差分别<0.3 eV和<0.55 eV。
