Magnetic dimer and tetramer based on dmit – Preparation, crystal structures, physicochemical characterization and magnetic properties

The preparation, crystal structures and physicochemical characterization of two magnetic polymers, ethyl-triphenylphosphate (ETPP) [Ni(dmit)2] (compound 1) and propyl-triphenylphosphate (PTPP) [Ni(dmit)2] (compound 2) (dmit = 2-thioxo-1,3-dithiol-4,5-dithiolate), have been described. The magnetic susceptibilities (χm) have been measured between 10 and 300 K. The χm values of 1 can be well reproduced by the sum of the contributions from a standard Curie system and a dimer with negative exchange interaction of J/k = −320.59 K, which is extremely strong among dmit complexes. The dimer formation in Ni(dmit)2 anions have been ascertained by the crystal structure analysis. In 2, every two Ni(dmit)2 dimer molecules are connected by the short side-by-side distance between sulfur atoms, indicating the formation of a nonlinear tetramer. The magnetic susceptibility data have been fitted to a four-spin model using the g value obtained in EPR spectroscopy, and ended up with a plane-to-plane interaction of J1/k = −200.89 K and a sideways interaction J2/k = −33.69 K.