The reactions of AlCl3 center dot 6H(2)O and GaCl3 with 2-pyridylphosphonic acid (2PypoH(2)) and 4-pyridylphosphonic acid (4PypoH(2)) afford cyclic aluminum and gallium phosphonate structures of [(2PypoH)(4)Al-4(OH2)(12)]Cl-8 center dot 6H(2)O (1), [(4PypoH)(4)Al-4(OH2)(12)]Cl-8 center dot 11H(2)O (2), [(2PypoH)(4)Al-4(OH2)(12)](NO3)(8)center dot 7H(2)O (3), [(2PypoH)(2)(2Pypo)(4)Ga8Cl12(OH2)(4)(thf)(2)]-(GaCl4)(2)center dot 8thf (4), and [(2PypoH)(2)(2Pypo)(4)Ga8Cl12(OH2)(4)(thf)(2)](NO3)(2)center dot 9thf (5). Structures 1-3 feature four aluminum atoms bridged by oxygen atoms from the phosphonate moiety and show structural resemblance to the secondary building units found in zeolites and aluminum phosphates. The gallium complexes, 4 and 5, have eight gallium atoms bridged by phosphonate moieties with two GaCl4- counterions present in 4 and nitrate ions in 5. The cage structures 1 3 are interlinked by strong hydrogen bonds, forming polymeric chains that, for aluminum, are thermally robust. Exchange of the phosphonic acid for the more flexible 4PyCH(2)PO(3)H(2) afforded a coordination polymer with a 1:1 Ga:P ratio, {[(4PyCH(2)PO(3)H)-Ga(OH2)(3)](NO3)(2)center dot 0.5H(2)O}(x) (6). Complexes 1-6 were characterized by single-crystal X-ray diffraction, NMR, and mass spectrometry and studied by TGA.