A novel cesium hydroxygallophosphate with a layered structure built up of rutile ribbons: CsGa2(OH)2[(PO4)H(PO4)]

A new cesium gallophosphate, CsGa2(OH)2[(PO4)H(PO4)], with an original layer structure has been synthesized by hydrothermal route and characterized by single-crystal X-ray diffraction (R=0.0344R=0.0344, Rw=0.0319Rw=0.0319). Its structure crystallizes in the monoclinic space group P21/a   with cell parameters a=16.079(6)Å, b=5.9873(12)Å, c=4.5033(15)Å, β=93.36(4)°β=93.36(4)° and Z=2Z=2. It consists of [Ga(OH)PO4]∞ layers built up of rutile ribbons interconnected through PO4 tetrahedra. The structure of CsGa2(OH)2[(PO4)H(PO4)] is closely related to those of (NH4)Ga(OH)PO4 and (en)Ga2(OH)2(PO4)2 (en=ethylenediamine [H3N(CH2)2NH3]2+). The three structures differ mainly from each other by the relative positions and the spacing of the successive layers, which are governed by different hydrogen bonding modes between [Ga(OH)PO4]∞ layers and the interleaved species. The title compound presents strong symmetric hydrogen bonds O---H---O which bridge two PO4 tetrahedra of two successive layers. As a consequence, the distance between the layers is significantly shorter than in the two other amine compounds.

View along c of the 2D structure of CsGa2(OH)2[(PO4)H(PO4)] exhibiting strong symmetric hydrogen bonds in dashed lines.Figure optionsDownload as PowerPoint slide