One-Step versus Two-Step Valence Tautomeric Transitions in Tetraoxolene-Bridged Dinuclear Cobalt Compounds.

The syntheses of valence tautomeric compounds with multistep transitions using new redox-active ligands are the long-term goal of the field of bistable materials. The redox-active tetraoxolene ligand, 2,7-di--butylpyrene-4,5,9,10-tetraone (pyrene), is now developed to synthesize a pair of dinuclear compounds {[CoL](pyrene)}[Co(CO)]·CHCl·2CHCH (, = 2, L = 1,10-phenanthroline, phen; , = 1.5, L = 2,2'-bipyridine, bpy).