Influence of Steric Hindrance of N-Heterocyclic Ancillary Ligands on the Structure and Magnetic Properties of Manganese(II) Coordination Polymers

摘要

Three biphenyl-3,5-dicarboxylic acid (H2L) based coordination polymers, namely, [Mn-3(L)(3)(2,2'-bpy)(2)](n) (1), {[Mn(L)(phen)]center dot(MeOH)}(n) (2), and [Mn(L)(dipt)](n) (3), (2,2'-bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline, and dipt = 2,9-dimethyl-1,10-phenanthroline) were synthesized and characterized by single-crystal X-ray diffraction and analyses of their magnetic properties. 1 is a trinuclear manganese structure with a 2D motifs, which can join by hydrogen bond bridges to give 3D supramolecular architectures. 2 has a dinuclear center forming a 1D supramolecular ladder chain. The mononuclear complex 3 displays 1D metal-organic chains driven by mu(2)-L linkers. Their structural differences were investigated, revealing that the influence of steric hindrance on the structures of acid-based coordination polymers is realized through changing the N-heterocyclic ancillaries of diverse steric hindrance. Obviously, with decreasing of the steric hindrance of the N-donor ligand, complexes 1-3 show structures from 1D to 2D and mononuclear to multinuclear. Magnetic susceptibility measurements indicate that 1 and 2 have dominating antiferromagnetic couplings between metal ions, whereas compound 3 is paramagnetic.