Two new amine-templated transition metal-based sulfates, [(CH3)(2)NH2](17.4) [SO4](0.7) [M-8(III)(mu(2)-OH)(8)(mu(2)-SO4)(16)] where M = Cr and Fe, have been synthesized via mild solvothermal synthesis. The compounds are isostructural and were refined in the monoclinic space group P2(1)/n. They feature the rare sulfate-bridged . inorganic molecular wheels [Cr-8(III)(OH)(8)(SO4)(16)](16-) and [Fe-8(III)(OH)(8)(SO4)(16)](16-). In both the octanuclear chromic (J = -2.4 cm(-1) based on (H) over cap (ex) = -J (S) over cap (i) . (S) over cap (j) convention) and ferric wheels (J = -38.3 cm(-1)), the coupling between the adjacent metal ions is antiferromagnetic giving spin-singlet ground states. The variation in the magnitude of the exchange coupling constants is due to the differences in the superexchange mechanisms, namely, a pi-pathway for the Cr-and a sigma-pathway for the Fe-wheel cluster.