The ligand and quadrupole interactions parameters have been measured at 4.2 K by ENDOR for three shells of ^35,37Cl, ¹³³Cs and ²³Na neighbours around Cr³⁺ and Yb³⁺ substitutional impurities. The ligand interaction parameters were analysed by means of expressions for spin densities obtained by the configurational interaction method. The quadrupole interaction parameters have been discussed in terms of a point-dipole model, and local deformation around the magnetic ions being taken into account.