The structural relations of (and between) late transition metal monoxides, MO, and monosulfates, MSO4, are analyzed. We show that all of these late transition metal oxides, as well as 4d and 5d metal sulfates, crystallize in distorted rock salt lattices and argue that the distortions are driven by collective first- and/or second order Jahn–Teller effects. The collective Jahn–Teller deformations lead either to tetragonal contraction or (seldom) elongation of the rock salt lattice. On the basis of the rock salt representation of the oxides and sulfates, we show that PdO, CuO, and AgO are metrically related and that the 4d and 5d metal sulfates are close to isostructural with their oxides. These observations guide us towards as yet unknown AuO and PtSO4, for which we predict crystal structures from electronic structure calculations.