Neutral Low-Dimensional Assemblies of a Mn(III) Schiff Base Complex and Octacyanotungstate(V): Synthesis, Characterization and Magnetic Properties

Abstract

Two novel low-dimensional molecular magnetic materials were prepared by a self-assembling of 3d-and 5d-metal complexes. These are the first neutral heterobimetallic cyanobridged compounds involving one anisotropic Mn(III) Schiff base complex and one octacyanotungstate(V) per molecular unit. A slow diffusion of the constituents' solutions leads to a formation of the 0D crystalline complex 1 due to coordination of a water molecule to the Mn center prevents a polymer formation. A rapid mixing of reagents results in a precipitation of the microcrystalline powder of the complex 2, which on a totality of experimental data possess 1D polymeric structure. The magnetic studies have shown that antiferromagnetic exchange interactions are dominating in 1 J/kB= -13.1(7) K, D=-3.0(1.3) K, zJ'= -0.16(20) K and gav=2.00(1); while the presence of the significant intramolecular Mn(III)-W(V) ferromagnetic couplings through cyanide bridges is characteristic for 2 (J/kB = 46.1(5) K gMn = 2.11(3), fixed gW = 2.0). Due to the weak interchain interactions, zJ'/kB = -0.8(2) K, compound 2 is a metamagnet with the Néel temperature of 9.5 K undergoing a spin-flip transition at 2 kOe. The slow magnetization dynamics of 2 was investigated at DС field of 0 and 2 kOe, giving the values of τ0 32(15) and 36(15) ps respectively, well within the range typical for SCMs. The respective ∆τ/kB values were 48.4(1.2) and 44.9(1.0) K.