X-BAND ELECTRON-PARAMAGNETIC-RESONANCE OF A QUASI-BIDIMENSIONAL MOLECULAR COMPOSITE [NH3-(CH2)(4)-NH3]CUCL4

Electron paramagnetic resonance (EPR) experiments on a single crystal of [NH3-(CH2)(4)-NH3]CuCl4, with a quasi-bidimensional structure, have been carried out when rotated around a, b and c axes, at X-band. A c areful analysis of experimental data permits one to obtain the princip al values of the g-factors g(perpendicular to) = 2.047 g(parallel to) 2.274. In the (a, c) plane, where CU2+ ions are magnetically equivale nt, and in theta, b) plane, where the exchange interaction is great, t he linewidth anisotropy is governed by anisotropic exchange and the an tisymmetric exchange. In the (b, c) plane perpendicular to the layers , where the exchange interaction between dissimilar ions is weak, the linewidth exhibits, in addition, a contribution from magnetically ineq uivalent sites. The exchange interaction between dissimilar copper ion s for the compound under study is determined by computer simulations o f the first derivative EPR absorption spectra. Along the bisector of(b , c) plane, the exchange interaction is practically equal to zero whe reas along the direction (theta = pi/2, phi = pi/4) of the mineral lay ers we have J' = (0.16 +/- 0.01) cm(-1).