One-Dimensional Co^II and Ni^II Helical Coordination Polymers Exhibiting Zero-Field Splitting

Abstract

Two new coordination polymers {[MII(HL)(EtOH)2](ClO4)}n, where MII= Co (1) and Ni (2), were synthesized using a Schiff base ligand H2L = 2-{[(E)-1H-imidazol-4-ylmethylidene}amino]benzoic acid. Compounds 1 and 2 are isostructural, presenting a one-dimensional helical chain arrangement. Each metal center has a distorted octahedral geometry bridged by a syn-anti carboxylate group. The fitting of the magnetic susceptibility data in the 1.8–300 K range shows weak intrachain antiferromagnetic interaction for 1 and weak ferromagnetic interaction for 2, with the presence of zero-field splitting (zfs) phenomenon in both compounds. Theoretical calculations confirm the weak intrachain coupling in both compounds, but with a zfs phenomenon dominant at lower temperatures. A positive value for the zfs is also obtained, with a major spin–orbit coupling component.

Cobalt(ii) coordination polymers with single-ion magnet property

“…Then, a number of 1D Co(II) compounds exhibiting SIM property were reported using distinct organic linkers and showing varying topologies (Table 1). [72][73][74][75][76][77][78][79][80][81][82][83] Notably, Wang and co-workers reported the structural and magnetic tuning in three homospin 1D chains constructed by a pentagonal bipyramidal Co II building units and organic ligands of different lengths (Fig. 2b).…”

“…Recently, there also has been a growing interest in the construction of Co( ii ) coordination polymers that contain mononuclear Co 2+ ions and exhibit slow relaxation of magnetization. 71–110 This trend represents a significant direction in the development of molecular framework nanomagnets. Theoretically, the spin dynamics of isolated magnetic molecules can be significantly enhanced by molecular vibrations.…”