AbstractEPR results for copper(II) ions doped in (gly)2CaCl2· 4H2O single crystals are reported. The copper(II) complex formed in the chromophore CuN2Cl4displays rhombic crystal field symmetry with an unusual spin‐Hamiltonian parameter sequence:gx= 2.115,gy= 2.034,gz= 2.308, andAx= 40.1,Ay= 113.4,Az= −73.0 × 10−4cm−1. Theg‐factors are related to the ground state wave function α |ad x 2‐y 2−bd z 2〉 with α2= 0.86,a= 0.9835, andb= 0.181, and the untypical hyperfine splitting parameters result from the very low value of the Fermi c