Structure and magnetic properties of polynuclear copper(II) compounds with syn-anti carboxylato- and bromo-bridges

Synthesis, spectroscopic and magnetic properties, and X-ray crystal structures of two copper(II) polymers Cu(2-qic)Br (2-qic = quinoline-2-carboxylate) (1) and Cu(2-pic)Br (2-pic = pyridine-2-carboxylate) (2) are described. Both complexes are polynuclear copper(II) compounds (1D and 2D, respectively) based on syn-anti carboxylate bridges and additionally on linear monobromo- (in 1) and dibromo-bridging (in 2) motifs. The magnetic properties investigated in the temperature range 1.8-300 K reveal the occurrence of strong antiferromagnetic coupling (J1 = −102.5 cm−1) through the single bromo-bridge in 1. For 2 a weak ferromagnetic couplings through the syn-anti carboxylate (zJ′ = 1.35 cm−1) and dibromo-bridges (J = 8.31 cm−1) were found.