Syntheses, structures and magnetic properties of two isostructural dicyanamide-bridged 2D polymers†‡
Abstract
Complexes [Co(biq)(μ1,5-dca)2]n (1) and [Ni(biq)(μ1,5-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 μ1,5-bridging dca ligands. The structures are stabilized by π–π interactions between the aromatic rings of biq and the weak C–H⋯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.
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