Selective oxidation and reduction of trinuclear titanium(II) hexaazatrinaphthylene complexes-synthesis, structure, and electrochemical investigations.

Titanocene complexes with chelating N-heterocyclic ligand bridges react with ferrocenium salts as selective oxidants to afford air-stable cationic complexes and allow the preparation of exceptional mixed valence hexaazatrinaphthylene complexes [(Cp2Ti)3(μ3-HATNMe6)]n+ (1n+) (n = 1, 2, 3, 4). Cyclic voltammograms (CV) and differential pulse voltammograms (DPV) show that nine oxidation states of 1 are generated without decomposition. Comproportionation constants Kc have been calculated in order to determine the extent of electronic communication between the titanium centers. The Kc values of the mixed valence states are indicative of uncoupled (14+), moderately coupled (15+), and strongly coupled (1-, 1+, and 12+) systems. Small but significant structural changes occurring upon oxidation of neutral 1 are observed by X-ray structural analysis on 1+−14+. Anion−π interactions between the electron-deficient central ring of the HATNMe6 moiety and PF6- and BF4- counterions, respectively, are found for 12+, 13+, a...