Investigation of the magneto-structural phase transition in [1-benzyl-4-aminopyridinium][bis(maleonitriledithiolato)nickelate]

Abstract [1-benzyl-4-aminopyridinium][bis(maleonitriledithiolato)nickelate] contains [ni(mnt) 2 ] 2 ( S =1/2) tetramer units. It shows an unusual transition to a nonmagnetic ground state associated with a structural phase transition at T c =189 K. Based on the determination of the single crystal structure and the analysis of the temperature dependence of the magnetic susceptibility, we suggest the structural phase transition significantly enhances the afm coupling within a tetramer and thus drives the system towards a spin singlet ground state.