Two new Cu(II) complexes with 3-(2-pyridyl)pyrazol-based ligands: Synthesis, crystal structures, and magnetic properties

Abstract

In our efforts to investigate the relationships between the structures of ligands and their complexes, two structurally related 3-(2-pyridyl)pyrazole-based ligands, 1-[3-(2-pyridyl)pyrazol-1-ylmethyl]benzene ( L 1) and 3-[3-(2-pyridyl)pyrazol-1-ylmethyl]pyridine ( L 2), and their two Cu(II) complexes, [Cu( L 1) 2(NO 3)](NO 3)(CH 3CH 2OH) ( 1) and [Cu 2( L 2) 2(Cl) 4] ( 2), were synthesized and structurally characterized by elemental analyses, IR spectra and single crystal X-ray diffraction analysis. Complex 1 has a mononuclear structure, while 2 takes the dinuclear structure, which were further linked into higher-dimensional supramolecular networks by intra- or inter-molecular weak interactions, such as C–H⋯O hydrogen-bonding, C–H⋯π, and π⋯π stacking interactions. The structural differences of 1 and 2 can be attributed to the difference of counter anions and the different pendant aromatic groups of L 1 and L 2, in which the benzene and pyridine rings act as the directing group for π⋯π stacking and C–H⋯π interactions. Moreover, magnetic properties of 2 have been further investigated in detail.