Spectral and magnetic properties of copper(II) naproxenates

The synthesis and characterisation of Cu(naproxenate)(2)L (where L = H2O, 1 ,4-dioxane or caffeine), and Cu(naproxenate)(2)L-2 (L = nicotinamide or 3-p yridylcarbinol) is reported. The characterisations were based on elemental analysis, electronic and EPR spectra, and magnetic susceptibility measureme nts over the temperature range 79-300 K. The available evidence supports a pseudo-octahedral arrangement about the Cu(II) atom for Cu(nap)(2)H2O and C u(nap)(2)L-2 with a spin S = 1/2. Magnetic susceptibilities obey the Curie- Weiss law. For Cu(nap)(2)caffeine and Cu(nap)(2)dioxane 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-pyridylc arbinol derivative. (C) 2000 Elsevier Science S.A. All rights reserved.