The hydrated potassium hemimagnesium dihydrogen pyrophosphate KMg 0.5H2P2O7·H2O was synthesized. It crystallizes in the triclinic system, space group P1̄ (n. 2), Z=2, with the following unit-cell parameters: a=6.8565(2)Å, b=7.3621(3)Å, c=7.6202(3)Å, α=81.044(2)°, β=72.248(2)°, γ=83.314(3)°, V=360.90(2)Å3. The structure was obtained by single-crystal X-ray diffractometry, and a full-matrix least-squares refinement based on F2 gave a final R index of =0.0368 (wR=0.0975), utilizing 1446 observed reflections with I>2σ(I). The crystal packing consists in a three-dimensional network made by layers parallel to ab plane of PO4 double tetrahedra and MgO6 octahedra, linked by hydrogen bonds, while K atoms form complex coordination within cavities between tetrahedra and octahedra. The dihydro-pyrophosphate anion (H2P2O7) 2- shows bent eclipsed conformation and the Mg2+ ion lies on inversion center. No coincidences observed between most of infrared and Raman spectral bands confirmed the centrosymm...
Synthesis, X-ray crystal structure and vibrational spectroscopy of the acidic pyrophosphate KMg0.5H2P2O7.H2O
BERTOLASI, Valerio
2003
Abstract
The hydrated potassium hemimagnesium dihydrogen pyrophosphate KMg 0.5H2P2O7·H2O was synthesized. It crystallizes in the triclinic system, space group P1̄ (n. 2), Z=2, with the following unit-cell parameters: a=6.8565(2)Å, b=7.3621(3)Å, c=7.6202(3)Å, α=81.044(2)°, β=72.248(2)°, γ=83.314(3)°, V=360.90(2)Å3. The structure was obtained by single-crystal X-ray diffractometry, and a full-matrix least-squares refinement based on F2 gave a final R index of =0.0368 (wR=0.0975), utilizing 1446 observed reflections with I>2σ(I). The crystal packing consists in a three-dimensional network made by layers parallel to ab plane of PO4 double tetrahedra and MgO6 octahedra, linked by hydrogen bonds, while K atoms form complex coordination within cavities between tetrahedra and octahedra. The dihydro-pyrophosphate anion (H2P2O7) 2- shows bent eclipsed conformation and the Mg2+ ion lies on inversion center. No coincidences observed between most of infrared and Raman spectral bands confirmed the centrosymm...I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
