A Delocalized Cobaltoviologen with Seven Reversibly Accessible Redox States and Highly Tunable Electrochromic Behaviour

Cobalt(II) mediates electronic coupling between two N-methyl-pyridinium-terpyridine ligands that are related to redox-active N,N-dialkyl-4,4'-bipyridinium dications (viologens). Borderline Class II/III electronic delocalization imparts the cobaltoviologen complex with distinct electronic properties (e.g. 7 accessible redox states) relative to those of viologens, leading to enhanced electrochromic properties.