Effective Anisotropic Interactions in Spin Pairs Containing High-Spin Ions with Large Zero-Field Splitting NeumanNicolás I. 2017 Analytic and numeric derivations are made of the effective exchange and dipolar magnetic interactions between spin pairs containing <i>S</i> = 3/2 ions, such as high-spin Co­(II), <i>S</i> = 5/2 ions, such as high-spin Fe­(III) ions, experiencing zero-field splittings much larger than the interion interactions, or <i>J</i> = 15/2 ions such as Dy­(III) with crystal-field splittings much larger than the interion interaction. These formulas allow for a simpler analysis of the magnetic properties of dimers containing high-spin ions.