Syntheses, structures and magnetic properties of two isostructural dicyanamide-bridged 2D polymers

Complexes [Co(biq)(mu(1,5)-dca)(2)](n) (1) and [Ni(biq)(mu(1,5)-dca)(2)](n) (2) (biq is 2,2'-biquinoline, dca is dicyanamide anion, N(CN)(2)(-)) have been characterized by crystal structure analysis, and spectral and magnetic measurements. The crystal structures of isostructural complexes 1 and 2 confirmed their polymeric two-dimensional system through the one double and two single mu(1,5)-bridging dca ligands. The structures are stabilized by pi-pi interactions between the aromatic rings of biq and the weak C-H center dot center dot center dot N hydrogen bonding interactions. The analysis of the magnetic response revealed the presence of the easy-plane anisotropy in 1 with D = 66.4 cm(-1) and the presence of the easy-axis anisotropy in 2 with D = -5.76 cm(-1) in good agreement with SA-CASSCF/NEVPT2 based ab initio predictions. Compound 1 exhibits a field-induced slow magnetic relaxation with a very long relaxation time, which was ascribed to the direct relaxation process influenced by the presence of the phonon-bottleneck effect with T-1.62 temperature dependence of the relaxation time in the applied magnetic field.

Automated summary

The complexes [Co(biq)(mu(1,5)-dca)(2)](n) (1) and [Ni(biq)(mu(1,5)-dca)(2)](n) (2) have been characterized by crystal structure analysis and magnetic measurements. The structures exhibit different magnetic responses and properties, with compound 1 showing easy-plane anisotropy and compound 2 showing easy-axis anisotropy.