Electrostatic equilibrium and charge factors in lanthanide complexes

Based on electrostatics and symmetry, a method to define equivalent nearest neighbours (NN) of the lanthanide ion in complexes is described. Equivalent NN have the same charge factor. The sum of the NN charge factor is required to equal the central ion valence. The high coordination number in lanthanide complexes is explained and the effective charge of the Simple Overlap Model is interpreted as a quantitative demonstration of the weak crystal-field perturbation on the luminescent site. The discussion on the central ion charge is made using the Batista–Longo Improved Model.