The theory of Stevens for covalent XY₆ complexes is developed for the cases of d³ and d⁵ with low symmetry, and compared with the magnetic resonance results of the preceding paper. The effect of the coupling to the doublet states on the spin Hamiltonian constants for the d³ complexes is found to be small compared with that of coupling to the quartet states, although the latter are probably further removed energetically. In the d⁵ complexes it is shown that the relation between the g-values and the susceptibility does not depend on the orientation of the principal axes of the g tensor relative to the complex; the principal values of the susceptibility of K₃Fe(CN)₆ are calculated from the g-values and compared with earlier experimental determinations, the value of the spin-orbit coupling being adjusted to give the best fit. The observed hyperfine constants for K₄Mn(CN)₆3H₂O are compared with the theoretical expressions and can be explained with reasonable values of the parameters. The orbital g-factor k is found to be 0.87 for the ferricyanide and 0.74 for the manganocyanide. An appendix discusses the conditions under which hyperfine terms of low symmetry can appear in the spin Hamiltonian, and the effect they may have on the observed spectrum.