Coordination Chemistry of Single-Site Catalyst Precursors in Reductively Electropolymerized Vinylbipyridine Films

Reductive electropolymerization of [Ru-II(PhTpy)(5,5'-dvbpy)(Cl)](PF6) and [Ru-II(PhTpy)(5,5'-dvbPY)(MeCN)](PF6)(2) (PhTpy is 4'-phenyl-2,2':6',2 ''-terpyridine; 5,5'-dvbpy is 5,5'-divinyl-2,2'-bipyridine) on glassy carbon electrodes gives well films of poly{[Ru-II(PhTpy)(5,5'-dvbpy)(Cl)] (PF6)} (poly-1) or poly{[Ru-II(PhTpy)(5,5'-dvbpy)(MeCN)](PF6)(2)} (poly 2) Oxidative cycling of poly-2 with added NO3- results in the replacement of coordinated MeCN by NO3-, to give poly{[Ru-II(PhTpy) (5,5'-dvbpy) (NO3)](+)}, and with 0.1 M HClO4, replacement by H2O occurs to give poly{[Ru-II(PhTpy)(5,5'-dvbpy)(OH2)](2+)} (poly-OH2). Although analogous aqua complexes (e g, [Ru(tpy)(bpy)(OH2)](2+)) undergo rapid loss of H2O to MecN solution, poly-OH2 and poly-OH2+ are substitutionally inert in MeCN. The substitution chemistry is reversible, with reductive scans of poly-1 or poly-OH2 in MeCN resulting in poly-2, although with some loss of Faradaic response.