Synthesis, structural and spectroscopic properties of two new ethylenediamine-templated gallophosphate-oxalate layered materials

Two new layered gallophosphate-oxalate materials have been prepared hydrothermally using ethylenediamine and oxalic acid as structure-directing agents. The compounds (C2N2H10)(2)[Ga-2(C2O4)(2)(HPO4)(3)].H2O 1 and (C2N2H10)(3)[Ga-4(C2O4)(4)(HPO4)(4)(H2PO4)(2)] 2 are closely related, consisting of anionic double chains built of alternating pairs of GaO6 and HPO4 polyhedra. These double chains are linked via bridging HPO4 or H2PO4 tetrahedra to form corrugated layers containing eight-membered rings. The oxalate group acts as a bidentate ligand to each of the GaO6 octahedron, The corrugated layers are held together by strong to weak hydrogen-bonding interactions between oxalate groups, water and diprotonated ethylenediamine molecules, and the framework components. The compounds were characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and infrared and Raman spectroscopy. Crystal data for 1: monoclinic, space group P2(1)/c (No. 14), a = 6.355(1) Angstrom, b = 39.362(8) Angstrom, c = 9.249(2) Angstrom, beta = 106.7(1)degrees, Z = 2. Crystal data for 2: triclinic, space group P (1) over bar (No. 2), a = 8.730(1) Angstrom, b = 11.575(1) Angstrom, c = 11.696(1) Angstrom, alpha = 115.12(1)degrees, beta = 90.07(1)degrees, gamma = 111.23(1)degrees, Z = 2.