Synthesis, crystal structure and magnetic characterization of two new ion-pair complexes containing bis(maleonitriledithiolate)nickelate anion and substituted benzylpyridinium cation

Two new ion-pair complexes, [FBrBzPyN(CH3)2]2[Ni(mnt)2] (1) and [FBrBzPyN(CH3)2][Ni(mnt)2] (2) form a 2D or 3D network structure through weak interactions. Magnetic susceptibility measurements in the temperature range 2-300 K show that 1 is expected to be diamagnetic, and 2 exhibits an interesting spin-gap transition (Δ/kb = 460.6 K) around 155 K.