Syntheses and structural characterizations of a mixed dipodal ligand, 1-tetrazole-phenyl-4-methyphosphonic acid. Hydrothermal synthesis of the two-dimensional Cu(II) phosphonate coordination polymer (1·H2O). Hydrothermal synthesis of the one-dimensional cobalt(II) analogue (2·2H2O). Correlation of structure with competing ferromagnetic coupling and antiferromagnetic coupling for (2·2H2O).