Two novel group 13 metal diphosphonates: (H(3)NC(3)H(6)NH(3))(2)[Al(2)F(6)(O(3)PC(2)H(4)PO(3))] . H(2)O (1) (monoclinic, C2/c, a = 16.9697(7) Angstrom, b = 8.0273(4)Angstrom, c = 16.3797(8) Angstrom, beta = 117.762(2)degrees, Z = 4, R(1) = 4.66%, wR(2) = 11.82%), and (H(3)NC(3)H(6)NH(3)) [Ga(2)F(4)(O(3)PC(2)H(4)PO(3))] (2) (triclinic, P-1, a = 5.398(7) Angstrom, b = 8.122(6)Angstrom, c = 15.839(18)Angstrom, alpha = 78.89(4)degrees, beta = 89.60(7)degrees, gamma = 79.35(6)degrees, Z = 2, R, = 2.90%, wR(2) = 3.17%) have been synthesized by solvothermal methods in the presence of the propyldiammonium cations and their structures determined using single and micro-crystal X-ray diffraction data, respectively. The structures of I and 2 are closely related and contain dimers of edge-sharing trivalent metal centered octahedra that are linked together by the ethylenediphosphonate groups to form chains and aperture-containing layers, respectively. The propyldiammonium cations surround the aluminum diphosphonate chains in I and separate the gallium diphosphonate layers in 2. Both compounds 1 and 2 are examples of metal phosphonate materials containing only one type of octahedral-tetrahedral secondary building unit (SBU-4). (C) 2004 Elsevier Inc. All rights reserved.