Magnetic interactions in 3-dimensional B.C.C. Heisenberg ferromagnets. IV: Analysis of the experimental results and discussion of the covalency effects

The experimental results on the NMR investigation of the six isomorphous crystals with the K₂CuCl₄.2H₂O structure, as reported in previous papers, are analysed. The covalency effects within the CuCl₄.2H₂O^2- octahedron are described by a molecular orbital model. Good agreement between the copper electronic g tensor and nuclear hyperfine interaction tensor on the one hand, and the ligand spin-transfer coefficients on the other hand is obtained. The importance of spin transfer from the ligands towards the empty copper 4s and 4p orbitals is outlined.

The superexchange interactions in these compounds are discussed qualitatively on the basis of the ligand spin-transfer coefficients.