Compound [Y(Hdo3aP(ABn))(H2O)][Y(Hdo3aP(ABn))]center dot 6H(2)O center dot iPrOH, where H(4)do3aP(ABn) is 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic-10-methyl(4-aminobenzylph osphinic) acid, a monophosphinate analogue of H(4)dota, was prepared in the solid state and studied using X-ray crystallography, In contrast to all single-crystal structures of complexes of H(4)dota-like ligands published before, three distinct units were found in one cell: two species adopting a twisted-square-antiprismatic configuration with (TSA) and without (TSA') a coordinated water molecule and one isomer with a square-anti prismatic configuration (SA), In addition, this is the first complex with the H(4)dota-like ligand for which the structures of three possible species were determined in the solid state.