Universal `bond valence versus bond length' correlation curve for manganese-oxygen bonds

The oxidation-state independent `bond valence (s) versus bond length (r)' correlation curve for manganese-oxygen bonds has been closely approximated using the two-parameter s = f(r) function s = [(r₀ - l)/(r - l)]², where r₀ = 1.763 (2) Å and l = 1.148 (9) Å.