A Three-Dimensional Coordination Framework with a Ferromagnetic Coupled Ni(II)-CrO₄ Layer: Synthesis, Structure, and Magnetic Studies

Abstract

We report herein on the crystal structure and magnetic studies of a three-dimensional (3D) Ni(II)-chromate coordination polymer, [Ni(CrO4)(bpym)(H2O)]n (1; bpym = 5,5′-bipyrimidin), prepared by self-assembly of Ni(II) and chromate ions with a multi-N donor auxiliary ligands, bpym, through hydrothermal processes. The structure of 1 is composed of Ni(II)-CrO4 layers with [Ni3(μ3-CrO4)] triangular motifs, in which the Ni(II) centers are bridged by O′:O′:O′:μ3-CrO42− anions, and the resulting layers are further connected by twisted trans-μ2-N,N′-bpym auxiliary ligands to form a 3D pillar-layered network with an hms topology. The magnetic properties of compound 1 were illustrated by variable field and temperature magnetic susceptibility measurements. The findings reveal that compound 1 shows intralayer ferromagnetic interactions within Ni(II)-CrO4 layers, and furthers the 3D antiferromagnetic ordering in the resulting of interlayer antiferromagnetic couplings with a Néel temperature (TN) of 5.6 K. In addition, compound 1 shows the field-induced metamagnetic behavior at temperature below the TN.

Keywords

• magnetic coordination polymer
• chromate-bridge
• pillar-layered network
• ferromagnetic
• antiferromagnetic
• magnetic ordering