New Titanium and Nickel Gallophosphates with Layered Structures

Two new transition-metal gallophosphates, (H₂C₄H₁₀N₂)₃[(Ti_2.5(H₂O)₄Ga_5.5(PO₄)₁₀]·2H₂O (TGP-1) and [H_3.5(C₄H₁₃N₃)₂][(Ni_0.5(OH)₄Ga_5.5(PO₄)₃(HPO₄)₄]·2H₂O (NGP-1), have been synthesized under mild hydrothermal conditions and characterized by single-crystal X-ray diffraction, thermogravimetric analysis, electron paramagnetic resonance, electron probe microanalysis, and magnetic susceptibility data. TGP-1 exhibits a unique two-dimensional structure consisting of tetrahedral and octahedral metals centers and is the foremost paramagnetic TiGaPO material ever prepared. NGP-1 as well represents the first NiGaPO compound and adopts a layer structure that is constructed from hexameric M−O clusters of trigonal bipyramids and octahedra. In both compounds, the transition metals incorporate with gallium into octahedral sites only, while the four- and five-coordinated metals centers are only Ga³⁺ ions. The unique sites for Ti³⁺ and Ni²⁺ ions have been initially elucidated from single-crystal structure refinements and further confirmed by bond-valence-sum calculations, EPR, and magnetic susceptibility studies. Crystal data:  TGP-1, monoclinic, P2₁/c; a = 25.692(2) Å, b = 9.6552(8) Å, c = 9.8418(8) Å, β = 96.737(2)°, V = 2424.5(3) ų, and Z = 2; NGP-1, monoclinic, C2/c, a = 20.8363(12) Å, b = 11.9546(7) Å, c = 16.4577(9) Å, β = 117.285(1)°, V = 3643.3(1) ų, Z = 4.