One-dimensional (1D) [Ni(mnt)₂]^--based spin-Peierls-like complexes: Structural, magnetic and transition properties

1D spin-Peierls-like complexes assembled from [Ni(mnt)₂]^- with Λ-shaped 1-(4′-R-benzyl)pyridinium derivatives (R represents a substituent) are reviewed, with data on their crystal structures, magnetic properties under ambient conditions as well as under pressure, and the nature of the paramagnetic-to-nonmagnetic transition. In this series of 1D spin systems, the correlation between the magnetic exchange and the anion stacking pattern is addressed by application of density functional theory (DFT) combined with a broken-symmetry approach. The qualitative relationship between the transition enthalpy change and the variation of the magnetic susceptibility in the low-temperature phase is determined. The influence of nonmagnetic doping on the structural and magnetic properties and the magnetic transitions are reported. Furthermore, the effect of the substituent group in the phenyl ring of the cation on the transition temperature and the origin of the transition are discussed.