Ligand mixed-valence and electrical conductivity in coordination complexes containing a redox-active phenalenol-substituted ligand

A new redox-active hydrazone ligand bearing a phenalenol group is described (phpl), which produces neutral six-coordinate Fe and Co complexes ( 1 & 2 ) with the ligands identified in different oxidation states; an open-shell anion radical and closed-shell dianion. An intense and very low-energy intervalence charge transfer (IVCT) band is identified in solid-state and in solution in the complexes. Single crystals of 1 are semiconducting (at 300 K, σ = 3.05 × 10 −4 S cm −1 with E a = 245 meV). Neutral Fe 3+ and Co 3+ complexes are reported featuring mixed-valent open- and closed-shell ligands, low energy IVCT bands and electrical conductivity.