Tuning Charge-State Localization in a Semiconductive Iron(III)–Chloranilate Framework Magnet Using a Redox-Active Cation

The elucidation of mechanisms to modulate the properties of multifunctional electroactive, conductive, and magnetic porous materials is desirable to aid their future application. The synthesis and characterization of a two-dimensional (2D) mixed-valence metal–tetraoxolene coordination polymer containing a redox-active dication, (PhenQ)[Fe2(Clan)3]·solvent (1; Clann– = deprotonated 3,6-dichloro-2,5-dihydroxy-1,4-benzoquinone; PhenQ2+ = 5,6-dihydropyrazino[1,2,3,4-lmn][1,10]-phenanthrolindiium), are reported. The PhenQ2+ cation in 1 introduces additional accessible framework redox states and effectively directs the localization of ligand valence states. Static and dynamic magnetic susceptibility measurements demonstrated that the dimethylformamide (DMF) solvate, 1b, undergoes spontaneous magnetization below Tc = 31 K, with variable-temperature electrical conductivity measurements revealing that 1b is a modest semiconductor with a conductivity of σ295K = 4.9 × 10–4 S cm–1 (Ea = 0.249(2) eV). In concert, these results demonstrate that introducing noncovalent interactions between anionic metal–tetraoxolene frameworks and redox-active cations is an effective method to alter the electronic structure and properties of these porous frameworks. Moreover, they forecast the synthesis of new anionic metal–tetraoxolene compounds with diverse electronic and magnetic properties using this hitherto unused strategy.