Complexes of a novel synthetic organometallic ionophore with lithium and sodium cations have been characterized by single-crystal X-ray diffraction. The crystal structure of the lithium complex consists of cation-ligand dimers with a tetrahedral coordination around Li. The sodium complex reveals a different structure type consisting of cation-ligand trimers, with water molecules being included between the trimeric entities. The coordination sphere around the Na ions has a distorted octahedral symmetry. It is anticipated that the observed structures of dinuclear Li and trinuclear Na complexes represent possible modes of aggregation of the cation-ligand entities in lipophilic media.