Water-Stable Manganese(IV) Complex of a N2O4‑Donor Non-Schiff-Base Ligand: Synthesis, Structure, and Multifrequency High-Field Electron Paramagnetic Resonance Studies

A novel water-stable (t1/2 ∼ 6.8 days) mononuclear manganese­(IV) complex of a hexacoordinating non-Schiff-base ligand (H4L) with N2O4-donor atoms has been synthesized and characterized crystallographically. High-frequency electron paramagnetic resonance experiments performed on a single crystal reveal a manganese­(IV) ion with an S = 3/2 ground spin state that displays a large single-ion anisotropy, setting the record of mononuclear manganese­(IV) complexes reported so far. In addition, spin–echo experiments reveal a spin–spin relaxation time T2 ∼ 500 ns.