Abstract
The crystal structure of β-Mg2PO4OH (P21/c, a = 9.656(3), b = 12.859(3), c = 12.069(4) Å, β = 108.49(3)°, Z = 16) has been refined isotropically to a final R-value of 0.052 for 1863 high-angle reflections. Fairly regular PO4 tetrahedra, distorted cis-MgO4(OH)2 octahedra, and distorted MgO4(OH) trigonal bipyramids are sharing either edges or vertices to build up a complex three-dimensional network. The variation in cell parameters for the solid-solution series Mg2PO4F – Mg2PO4OH with wagnerite structure is shown graphically. There are indications of preferred substitution of OH for F in the two ‘largest’ F/OH sites. Low valence sums in the bond-strength calculation are correlated with long Mg – O distances. Hydrogen bonding is relatively weak with strongly bent O – H⋯O bonds. The infra-red spectrum is briefly discussed.
© 2015 Oldenbourg Wissenschaftsverlag GmbH, Rosenheimer Str. 145, 81671 München
