Electrical Bistability around Room Temperature in an Unprecedented One-Dimensional Coordination Magnetic Polymer

The synthesis, crystal structure, and physical properties of an unprecedented one-dimensional (1D) coordination polymer containing [Fe₂(S₂C₆H₂Cl₂)₄]^2– entities bridged by dicationic [K₂(μ-H₂O)₂(THF)₄]²⁺ units are described. The magnetic properties show that the title compound presents pairwise Fe–Fe antiferromagnetic interactions that can be well reproduced with a S = 1/2 dimer model with an exchange coupling, J = −23 cm^–1. The electrical conductivity measurements show that the title compound is a semiconductor with an activation energy of about 290 meV and two different transitions, both with large hysteresis of about 60 and 30 K at 260–320 K and 350–380 K, respectively. These two transitions are assumed to be due to slight structural changes in the cation–anion interactions. Differential Scanning Calorimetry confirms the presence of both transitions. This compound represents the first sample of a coordination polymer showing electrical bistability.