Exploring the Structural Phase Transition, Dielectric Response, and Magnetic Properties of a New Isothiocyanate-Based Dinuclear Manganese Compound

The development of novel multifunctional organic–inorganic hybrid materials incorporating isothiocyanate ligands represents an ongoing challenge in chemistry and materials science. In this study, we successfully constructed a dinuclear manganese compound, [(CH3)3S]5[Mn2(SCN)9]. This compound exhibits a remarkable order–disorder transition of the isothiocyanate ligands and (CH3)3S+ cations, which drives reversible structural phase transitions (SPTs) with a critical temperature (Tc) of 206 K. Simultaneously, striking step-like anomalies are observed in the dielectric constant. Magnetic investigations reveal antiferromagnetic interactions between the dinuclear Mn2+ ions (J = −6.11 cm–1). These findings provide new theoretical foundations for designing multifunctional materials with tunable dielectric properties.