Spectral and magnetic properties of copper(II) naproxenates

The synthesis and characterisation of Cu(naproxenate)2L (where L=H2O, 1,4-dioxane or caffeine), and Cu(naproxenate)2L2 (L=nicotinamide or 3-pyridylcarbinol) is reported. The characterisations were based on elemental analysis, electronic and EPR spectra, and magnetic susceptibility measurements over the temperature range 79–300 K. The available evidence supports a pseudo-octahedral arrangement about the Cu(II) atom for Cu(nap)2H2O and Cu(nap)2L2, with a spin S=1/2. Magnetic susceptibilities obey the Curie–Weiss law. For Cu(nap)2caffeine and Cu(nap)2dioxane a dimeric structure is indicated with spin S=1, and a singlet–triplet energy gap of 384 and 270 cm−1, respectively. A chain structure is proposed for the 3-pyridylcarbinol derivative.