A series of triruthenium complexes with arylacetylide axial ligands Ru3(dpa)4(C2X)2(BF4)y
(dpa = dipyridylamido; X = Fc, y
= 0 (1); X = Ph, y
= 0 (2); X = PhOCH3, y
= 1 (3); X = PhC5H11, y
= 1 (4); X = PhCN, y
= 0 (5); X = PhNO2, y
= 0 (6)) have been synthesized. The crystal structures show that the RuâRu bond lengths (2.3304(9)â2.3572(5)
Ã
) of these compounds are longer than those of Ru3(dpa)4Cl2
(RuâRu2.2537(1)
Ã
). This is ascribed to the formation of the stronger Ï-backbonding from metal to axial ligand which weakens the RuâRu interactions and the bond order is reduced in the triruthenium unit. Cyclic voltammetry and differential pulse voltammetry show that compound 1 exhibits electronic coupling between the two ferrocenyl units with ÎE1/2 close to 100 mV. Compounds 2â6 display three triruthenium-based reversible one-electron redox couples, two oxidations and one reduction, and the electrode potentials shift upon varying the substituents. A linear relationship is observed when the Hammett constants are plotted against the redox potentials.
已经合成了一系列三
钌配合物,其轴向
配体为芳基
乙炔 Ru3(dpa)4(C2X)2(
BF4)y(dpa = 二
吡啶基酰胺;X = Fc,y = 0 (1);X = Ph,y = 0 (2);X = PhOCH3,y = 1 (3);X = PhC5H11,y = 1 (4);X = PhCN,y = 0 (5);X = PhNO2,y = 0 (6))。晶体结构显示,这些化合物的Ru-Ru键长(2.3304(9) - 2.3572(5) Å)比Ru3(dpa)4Cl2(Ru-Ru2.2537(1) Å)更长。这是由于
金属与轴向
配体之间形成了更强的Β-背键,从而削弱了Ru-Ru相互作用,三
钌单元中的键序也降低了。循环伏安法和差分脉冲伏安法显示,化合物1在两个
二茂铁单元之间表现出电子耦合,ΔE1/2接近100 mV。化合物2-6表现出三个三
钌基可逆一电子氧化还原对,两个氧化和一个还原,电极电位随着取代基的变化而