Three-dimensional acentric coordination polymers formed from the linkage of cobalt and nickel malonate quadratic layers through a kinked organodiimine: Synthesis, structure, thermal properties and magnetochemistry

Abstract

Hydrothermal synthesis has afforded a pair of isostructural acentric three-dimensional coordination polymers {[M 2(malonate) 2(dpa)(H 2O) 2] · 2H 2O} n (M = Co, 1; M = Ni, 2; dpa = 4,4′-dipyridylamine), which were structurally characterized via single-crystal X-ray diffraction and spectroscopically and thermally analyzed. Both materials exhibit exotridentate malonate ligands conjoining metal atoms into grid-like [M(malonate)(H 2O)] n layers; in turn, these are connected into 3-D sqp lattices (4 46 6 topology) through tethering dpa ligands. The central kink and inter-ring torsion within the dpa ligands enforces the acentric Aba2 space group of crystals of 1 and 2. Antiferromagnetic coupling ( g = 2.08(2), J = –1.05(8) cm −3) was observed within the malonate-bridged layer motifs within the cobalt derivative 1. In contrast, the nickel congener 2 exhibited ferromagnetic coupling ( g = 2.201(1), J = 0.289(1) cm −3).