Synthesis and characterization of organic-inorganic hybrid compounds with a pillared layer structure:: Ga2(4,4′-bpy)(XO4)2 (X = P, As)

Two organic-inorganic hybrid compounds, Ga-2(4,4'-bpy)(PO4)(2), 1, and Ga-2(4,4'-bpy)(AsO4)(2), 2, have been synthesized under hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction. The two compounds are isostructural and crystallize in the triclinic space group P (1) over bar (No. 2) with a = 4.9723(9) Angstrom, b = 5.770(1) Angstrom, c = 11.812(2) Angstrom, alpha = 78.268(3)degrees, beta = 89.159(3)degrees gamma = 88.344(3), V = 331.7(2) Angstrom(3), Z = 1, and R1 = 0.0377 for 1, and a = 5.1111(7) Angstrom, b = 5.9327(8) Angstrom, c = 11.788(2) Angstrom, alpha = 79.497(2)degrees, beta = 88.870(2)degrees, gamma = 88.784(2)degrees, V = 351.3(2) Angstrom(3), and R1 = 0.0264 for 2. The structure consists of neutral sheets of GaXO4 (X=P or As) which are pillared through 4,4'-bipyridine ligands. Each oxide layer, which is formed only by four-membered rings, is constructed from corner-sharing GaO4N trigonal bipyramids and XO4 tetrahedra. The title compounds are two of the few examples in which the gallium atoms are exclusively five-coordinate. (C) 2003 Elsevier Science (USA). All rights reserved.