New Gallium Phosphate Frameworks Containing 1,4-Diaminobutane and 1,5-Diaminopentane: [NH 3(CH 2) xNH 3][Ga 4(PO 4) 4(HPO 4)] and [NH 3(CH 2) xNH 3][Ga(PO 4)(HPO 4)] ( x=4 and 5)

Abstract

Two new gallium phosphates, [NH 3(CH 2) 4NH 3][Ga 4(PO 4) 4 (HPO 4)] (I) and [NH 3(CH 2) 4NH 3][Ga(PO 4)(HPO 4)] (II), have been synthesized under solvothermal conditions in the presence of 1,4-diaminobutane and their structures determined using room-temperature single-crystal X-ray diffraction data. Compound (I) ( M r=844.90, triclinic, space group P-1, a=9.3619(3), b=10.1158(3) and c=12.6456(5) Å, α=98.485(1), β=107.018(2) and γ=105.424(1)°; V=1070.39 Å 3, Z=2, R=3.68% and R w=4.40% for 2918 observed data [ I>3( σ( I))]) consists of GaO 4 and PO 4 tetrahedra and GaO 5 trigonal bipyramids linked to generate an open three-dimensional framework containing 4-, 6-, 8-, and 12-membered rings of alternating Ga- and P-based polyhedra. 1,4-Diaminobutane dications are located in channels bounded by the 12-membered rings in the two-dimensional pore network and are held to the framework by hydrogen bonding. Compound (II) ( M r=350.84, monoclinic, space group P2 1/ c, a=4.8922(1), b=18.3638(6) and c=13.7468(5) Å, β=94.581(1)°; V=1227.76 Å 3, Z=4, R=2.95% and R w=3.37% for 2050 observed data [ I>3( σ( I))]) contains chains of edge-sharing 4-membered rings of alternating GaO 4 and PO 4 tetrahedra constituting a backbone from which hang ‘pendant’ PO 3(OH) groups. Hydrogen bonding between the GaPO framework and the diamine dications holds the structure together. A previously reported phase, [NH 3(CH 2) 4NH 3][Ga 4(PO 4) 4(HPO 4)] (V), structurally related but distinct from its stoichiometric equivalent, (I), has been prepared as a pure phase by this method. Two further materials, [NH 3(CH 2) 5NH 3][Ga 4(PO 4) 4(HPO 4)] (III) (tricli- nic, lattice parameters from PXD: a=9.3565(4), b=5.0156(2) and c=12.7065(4) Å, α=96.612(3), β=102.747(4) and γ=105.277(3)°) and [NH 3(CH 2) 5NH 3][Ga(PO 4)(HPO 4)] (IV) ( M r=364.86, monoclinic, space group P2 1/ n, a=4.9239(2), b=13.2843(4) and c=19.5339(7) Å, β=96.858(1)°; V=1268.58 Å 3, Z=4, R=3.74% and R w=4.44% for 2224 observed room-temperature data [ I>3( σ( I))]), were also prepared under similar conditions in the presence of 1,5-diaminopentane. (III) and (IV) are structurally related to, yet distinct from (I) and (II) respectively.