Effect of coordinated base on magnetic behavior of copper(II) carboxylateswith patty acid chains (an ESR study)

The ESR spectra of a series of copper(II) alkanoates with the empirical for mula CU2X4 (X = heptanoate, octanoate, nonanoate, decanoate, dodecanoate), and their pyridine adducts have been measured over the temperature range 30 0K to 100K. The spectra of non-adduct copper(II) alkanoates exhibit extreme temperature dependent behavior; the room temperature spectra show a single broad line centered on g approximate to 2.1, however as the temperature is lowered triplet state features appear. The corresponding pyridine adducts give typical triplet state spectra at all temperatures. This temperature be havior can be interpreted in terms of interdimer interactions in copper(II) alkanoates having the polymeric structure. The observed resonance lines ar e used to calculate the zero- held splitting parameters D and E. The spin H amiltonian and zero- field splitting parameters are used to estimate the ex change parameter J. The values of \ 2J \ for the compounds investigated are in the range of 300-400cm(-1) and suggest that the copper(II) ions are str ongly antiferromagnetically coupled.