INVESTIGATIONS OF THE EPR PARAMETERS FOR Cu<sup>2+</sup> IN [Cu(ipt)(dap)H<sub>2</sub>O]<i><sub>n</sub> </i>×<i>n</i>H<sub>2</sub>O
The electron paramagnetic resonance (EPR) parameters (g factors and hyperfine structure constants) for Cu<sup>2+</sup> in [Cu(ipt)(dap)H<sub>2</sub>O] <sub>n</sub> × n H<sub>2</sub>O (ipt is isophthalic acid, dap - 1,3-diaminopropane) are theoretically investigated from the high order perturbation formulas of these parameters for a 3 d <sup>9</sup> ion in a rhombically elongated octahedron. The ligand orbital and spin-orbit coupling contributions are included from the cluster approach because of strong covalency of the system. The nearly axial anisotropies of the g factors and hyperfine structure constants are correlated to the significant elongation distortion of the five-fold coordinated Cu<sup>2+</sup> (in a distorted square pyramidal [CuN<sub>2</sub>O<sub>3</sub>] group). Nevertheless, the perpendicular anisotropies arising from the nonequivalent planar ligands are largely concealed by the experimental uncertainties. The theoretical analysis of the EPR behaviours for [Cu(ipt)(dap)H<sub>2</sub>O] <sub>n</sub> × n H<sub>2</sub>O would be helpful to understand the local structures and properties of this and relevant systems.