The structures and binding enthalpies of a single alkali metal cation complexed with up through four dimethyl ether (DME) ligands were obtained with Hartree-Fock wave functions and second-order perturbation theory, with consideration of core/valence correlation and relativistic effects. The basis sets used in this study included diffuse functions on oxygen, in order to minimize undesirable basis set superposition error, and polarization functions on all non-hydrogen atoms. The observed trends in complex formation energy along the sequence of cations are discussed and compared to the available experimental data obtained from collision-induced dissociation measurements. Minimum energy M+(DME)(2) geometries are predicted to be Linear for the light metal complexes and bent for the heavy metal complexes.