Differential Ion-pairing and Temperature Effects on Intervalence Charge Transfer (IVCT) in a Series of Dinuclear Ruthenium Complexes

Abstract

Thermochromism and anion-dependence studies on the intervalence charge transfer (IVCT) properties of the diastereoisomers of [{Ru(bpy)2}2(μ-BL)]5+ {BL = dpb′, dpq′, and dpb: dpb′ = dipyrido(2,3-a;3′,2′-c)benzophenazine; dpq′ = dipyrido(2,3-a;3′,2′-c)phenazine; dpb = 2,3-bis(2-pyridyl)-1,4-benzoquinoxaline} are reported. IVCT thermochromism studies revealed that the level of delocalisation may differ between the diastereoisomers for a system, and a slight temperature dependence in meso-[{Ru(bpy)2}2(μ-dpb)]5+ which was dependent on the identity of the counter-anion { or B(C6F5)4 -} Anion effects on the IVCT properties of the diastereoisomeric forms of the three complexes were observed to be somewhat unpredictable. X-ray crystal structure determinations on meso-[{Ru(bpy)2}2(μ-dpb)]4+ (as the and [ZnCl4]2- salts), meso-[{Ru(bpy)2}2(μ-dpb′)]4+ ( salt) and meso-[{Ru(bpy)2}2(μ-dpq′)]4+([ZnCl4]2- salt) revealed considerable distortion in the bridging ligand, particularly in the dpb-bridged species where the distortion was also dependent on the anion.