Syntheses and structures of two low-dimensional beryllium phosphate compounds: [C₅H₁₄N₂]₂[Be ₃(HPO₄)₅]·H₂O and [C ₆H₁₈N₂]_0.5[Be₂(PO ₄)(HPO₄)OH]·0.5H₂O

The first two low-dimensional beryllium phosphates, [C₅H ₁₄N₂]₂[Be₃(HPO₄) ₅]·H₂O (BePO-CJ29) and [C₆H ₁₈N₂]_0.5-[Be₂(PO₄) (HPO₄)OH]·0.5H₂O (BePO-CJ30), have been successfully synthesized under mild hydrothermal/solvothermal conditions. BePO-CJ29 is built up from strict alternation of BeO₄ and HPO ₄ tetrahedra forming a unique one-dimensional double chains with 12-ring apertures. There are pseudo-10-ring apertures enclosed by two double chains through H-bonds. BePO-CJ29 can also be viewed as a pseudo 2-D layered structure stabilized by strong H-bonds. The diprotonated 2-methylpiperazium cations are located at three positions (i.e., inside the 12-ring aperture, inside the pseudo-10-ring aperture, and in the interlayer of the inorganic pseudo-layers. BePO-CJ30 is constructed by the alternation of Be-centered tetrahedra (including BeO₄ and HBeO₄) and P-centered tetrahedra (including PO₄ and HPO₄) resulting in a two-dimensional layered structure parallel to the (0 1 1) direction. The complex layer is composed of coupled 4.8 net sheets. The diprotonated 1,6-hexandiamine cations and water molecules reside in the interlayer regions and interact with the inorganic layers through H-bonds. Crystal data are as follows: [C ₅H₁₄N₂]₂-[Be₃(HPO ₄)₅]·H₂O (BePO-CJ29), triclinic, P1 (No. 2), a = 8.1000(9) Å, b = 8.4841(14) Å, c = 19.665(2) Å, α = 89.683(10)°, β = 78.182(8)°, γ = 87.932(9)°, V = 1321.9(3) ų, Z = 2, R1 = 0.0523 (I > 2σ(I)), and wR2 = 0.1643 (all data); [C₆H₁₈N₂] _0.5[Be₂(PO₄)(HPO₄)OH]·0. 5H₂O (BePO-CJ30), orthorhombic, Pccn (No. 56), a = 26.01(4) Å, b = 8.431(12) Å, c = 9.598(13) Å, V = 2105(5) ų, Z = 8, R1 = 0.0833 (I > 2σ(I)), and wR2 = 0.2278 (all data).