Tuning the topologies of MnII complexes with 3-(2-pyridyl)pyrazole and carboxylate ligands by intramolecular hydrogen bonds and the geometries of pendant ligands:: crystal structures and magnetic properties

In our efforts to investigate the influence of intramolecular hydrogen bonding interactions and the geometries of pendant ligands on the structures of low-dimensional coordination architectures, two kinds of ligands have been selected: a) a chelating ligand, 3-(2-pyridyl) pyrazole (L-1), with a non-coordinated nitrogen atom as a good hydrogen bonding acceptor and b) three pendant monocarboxylato ligands with different aromatic backbones (L-2, L-3 and L-4), and their Mn-II complexes, [Mn(L-1)(2)(L-2)(2)] (1), [Mn(L-1)(2)(L-3)(2)] (2) and [Mn-2(L-1)(2)(L-4)(4)] (3), have been prepared and structurally characterized by single crystal X-ray diffraction analysis. The results show clearly that the chelating 3-(2-pyridyl) pyrazole ligand plays the dominant role in the adjustment of the modes of the monocarboxylate ligands through strong intramolecular hydrogen bonding interactions and results in the formation of low-dimensional coordination complexes. The geometry of the anthracene ring also plays a vital role in determining the topology of 3, which further affects the magnetic interactions between the metal centers.