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 [lcubRu(bpy)2rcub2(μ-BL)]5+ lcubBL = 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-benzoquinoxalinercub 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-[lcubRu(bpy)2rcub2(μ-dpb)]5+ which was dependent on the identity of the counter-anion lcub./GSCH_A_131036_images/GSCH_A_131036math001.gif or B(C6F5)4-rcub 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-[lcubRu(bpy)2rcub2(μ-dpb)]4+ (as the ./GSCH_A_131036_images/GSCH_A_131036math002.gif and [ZnCl4]2- salts), meso-[lcubRu(bpy)2rcub2(μ-dpb')]4+ (./GSCH_A_131036_images/GSCH_A_131036math003.gif salt) and meso-[lcubRu(bpy)2rcub2(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.