Spectroelectrochemical investigations of two dinuclear complexes [Ru-III(bpy)(2)(mu -BL)Ru-II(bpy)(2)](5+) (BL = 2,3-bis(2-pyridyl)-1,4-benzoquinoxaline (dpb); dipyrido-(2,3-a;3',2'-c)benzophenazine (dpb')) revealed that the intervalence charge transfer (IT) characteristics are sensitive to the stereochemistry. In particular, there appears to be a greater degree of metal-metal interaction in the meso compared with the rac diastereoisomeric form. Thermochromism. redox, and semiempirical computational studies suggest differential ion-paring between the diastereoisomeric forms.