Unusual magnetic property associated with a structural phase transition within a new ion-pair complex

A novel ion-pair complex, [BrbzPyNH2][Ni(mnt)2], where [BrbzPyNH2]+ = 1-(4′-bromobenzyl)-4-aminopyridinium and mnt2− = maleonitriledithiolate, forms a completely segregated uniform stacking column with the Ni⋯Ni distance 3.952 Å and undergoes a magnetic phase transition from paramagnetism in the high-temperature (HT) phase to diamagnetism in the low-temperature (LT) phase at around 105 K.