SwitchableAromaticity in an Isostructural Mn PhthalocyanineSeries Isolated in Five Separate Redox States

The synthesis and characterization of a new phthalocyanine (Pc) Mn-nitride complex, (OEtPc)MnN (2; OEtPc = 1,4,8,11,15,18,22,25-octaethoxy-Pc), as well as its stable, readily accessible oxidized (2+ and 22+) and reduced (2–, 22–) congeners is reported. This unique isostructural series displays switchable aromatic character spanning the aromatic (2), nonaromatic (22+), and antiaromatic (22–) triad, in addition to the open-shell radical states (2+, 2–). All complexes were structurally characterized and displayed significant structural distortions at the redox extrema (22+, 22–) consistent with proposed [16 or 18]annulene π ring circuit models. Spectroscopic and computational studies further support these models. This isolated, fully characterized, isostructural series spanning five redox states (22+, 2+, 2, 2–, 22–) is unique in both the Pc and related macrocyclic (ex. porphyrinoids) literature and may offer direct insight into structural–electronic correlations driven by switchable aromaticity.