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The monoclinic crystal structure of [NH3‐(CH2)2‐NH3]CuCl4 consists of two‐dimensional (b, c) layers of square planar (CuCl4)2— entities, separated from each other by [NH3‐(CH2)2‐NH3]2+ alkylene chain sheets. Electron Paramagnetic Resonance (EPR) data have been obtained in single crystals of 2C2CuCl4 when rotated around a*, b and c ‐axes, at X‐band. Only one EPR exchange‐collapsed line was observed for the two magnetically inequivalent copper ions in the lattice. The angular variation of its position and peak‐to‐peak linewidth were measured in three perpendicular planes. A careful analysis of experimental data permits to obtain the principal values of the g‐factor g⊥ = 2.053, g| = 2.274. The contributions to the linewidths were analyzed in terms of the antisymmetric exchange (d) and the anisotropic exchange (D) and yielded |dx/dy| = 0.92 and |(d2x + 2.2D2)1/2/dy| = 0.65. Lineshape studies show that the exchange between the two inequivalent copper ions is anisotropic.

EPR spectra of polycrystalline compounds MnSO4 · (NH4)2SO4 · 6H2O, Gd2(SO4)3 · 8H2O, and NH4Fe(SO4)2 · 12H2O are recorded at X‐band and room temperature. For the first two compounds, good agreement with simulated spectra of Gaussian lineshape is found, and the numerical values of the fine (D) and hyperfine (A) structure constants are obtained by fitting with experimental spectra. For the last compound, the fine structure characteristic of the cubic term (a) is responsible for the “hyper‐Gaussian” shape of the EPR line.