Solvent-induced two Cu(II) complexes with 4-acyl pyrazolone derivative: From discrete structure to 1D helical chain

Abstract

Two new copper(II) complexes [Cu2L2(CH3OH)]·CH3OH (1) and [CuL]n (2) (H2L=N-(1-phenyl-3-methyl-4-benzal-pyrazolone-5)-salicylidene hydrazide) with different structures have been synthesized by the reactions of copper acetate with the 4-acyl pyrazolone derivative H2L in MeOH or EtOH solvent, respectively. The X-ray diffraction analyses revealed that 1 displays a dinuclear structure which is further linked by weak coordination interactions and hydrogen bonds to generate an infinite 1D chain. Complex 2 exhibits 1D left-handed and right-handed helical chains structure in a 1:1 ratio along the c axis, and the 1D chains with the same handedness were linked by hydrogen bonds to form a racemic two-fold interpenetrated 3D framework. The results demonstrated that the solvents with different coordination abilities have significant effect on the structure of the complexes. On the other hand, the ligands H2L adopt tridentate chelating mode and tetradentate chelating-bridging mode to coordinate with Cu(II) ions in 1 and 2, which attested that the flexible 4-acyl pyrazolone Schiff base derivative can adopt different coordination modes to form complexes with varied structures. The variable temperature magnetic investigation indicates that 2 exhibits typical antiferromagnetic behavior.