Bis(R-bipyridyl)ruthenium bibenzimidazole complexes (R = H, Me or Bu-t): supramolecular arrangement via hydrogen bonds, photo- and electro-chemical properties and reactivity towards carbon dioxide

Complexes of the type [Ru(H(2)bibzim)(R-bpy)(2)X-2. nH(2)O (R = H, 2,2'-bip yridine, bpy, X = CF3SO3- 1; R = Me, 4,4'-dimethyl-2,2'-bipyridine, dmbpy, X = PF6- 2; R = tert-butyl, 4,4'-di-tert-butyl-2,2'-bipyridine, tbbpy, X = Cl- 3; H(2)bibzim = 1,1'-bibenzimidazole) containing two NH functions actin g as hydrogen bond donors formed different spatially highly organised supra molecular assemblies with water. X-Ray investigation revealed that the natu re of the counter ion influences the hydrogen bonding pattern and extent of spatial organisation. In 2 one dimensional chains of hydrogen bonded water could be found. In the deprotonated complex [Ru(bibzim)(tbbpy)(2)] 4 water molecules serve as hydrogen bond donors. The diastereomeric forms 5a/5b of the homodinuclear ruthenium complex [{Ru(tbbpy)(2)}(2)(bibzim)][PF6](2) co uld be separated. No differences in their photophysical properties could be detected. The X-ray investigation of 5a and [{Ru(bpy)(2)}(2)(bibzim)][PF6] (2) 6 showed little influence of peripheral substitution on structural prop erties. Complexes 3-5 exhibit activity in electrochemical CO2 reduction whi ch can be tuned by variation of the degree of protonation of the bibenzimid azole.