Synthesis, Crystal Structure and Magnetic Properties of a Copper(II) <i>p</i>-Formylbenzoate Complex

A new Cu(II) complex was prepared at room temperature from the reaction of p-formylbenzoic acid, phenanthroline, CuCl₂ ·2H₂O, and NaOH under ethanolic aqueous conditions. The complex has been characterized by X-ray diffraction, IR spectroscopy, TG-DTA analyses, and magnetic measurements. Single-crystal X-ray diffraction analysis indicated that the complex crystallizes in the triclinic space group P1̅ with the cell dimensions a = 7.875(2), b = 10.724(2), c = 15.317(3) Å, α = 102.65(3), β = 93.71(3), γ = 107.64(3)^○. The Cu atoms are in the environment of distorted CuN₂O₃ tetragonal pyramids. These discrete complex molecules are packed through intermolecular π ··· π-stacking interactions and C–H···O hydrogen bonds forming a supramolecular structure. The title complex obeys the Curie-Weiss law with a Curie constant C = 0.53 cm³ K mol⁻¹ and a Weiss constant θ = −0.27 K. The shape of the χ_mT curve is characteristic of weak ferromagnetic interactions between the Cu(II) centers from 300 to 7 K, while there are weak antiferromagnetic interactions below 7 K.