An infinite 2D sheet of tetragonal CoII framework exhibiting metamagnetism

Abstract

A two-dimensional coordination polymer [Co(pyz)(CA)]_n (complex 1) was synthesized and structurally characterized. Solid-state dc magnetic susceptibility revealed overall antiferromagnetic interactions in the complex with an antiferromagnetic ordering below 7 K (Néel temperature, T_N). Magnetization measurements revealed a sigmoidal nature indicative of metamagnetic behaviour, with an abrupt increase in magnetization at 4.7 T. Variable field susceptibility studies indicated a magnetic phase transition, marked by a cusp at 11 K that disappeared at fields above 0.05 T. Hydrostatic pressure decreased the overall magnetic moment without altering the T_N or the hysteresis width. Broken-symmetry density functional theory (BS-DFT) calculations indicated antiferromagnetic interactions between Co^II ions mediated by pyrazine and chloranilate anions, and also emphasized the significant role of easy-axis anisotropy of the Co^II ion in the metamagnetic behaviour in complex 1.