Syntheses, Crystal Structures, NMR Spectroscopy, and Vibrational Spectroscopy of Sr(PO3F)·H2O and Sr(PO3F)

Single crystals of Sr(PO3F)·H2O {P21/c, Z = 4, a = 7.4844(2) Å, b = 7.0793(2) Å, c = 8.4265(2) Å, β = 108.696(1)°, V = 422.91(2) Å3, 2391 Fo2, 70 parameters, R1[F2 > 2σ(F2)] = 0.036; wR2(F2 all) = 0.049, S = 1.054} were grown from an aqueous solution by a metathesis reaction. The structure comprises [SrO8] polyhedra and PO3F tetrahedra that form a layered arrangement parallel to (100). The topotactic dehydration of this phase proceeds between 80 and 140 °C to afford Sr(PO3F). The monazite‐type crystal structure of Sr(PO3F) was elucidated from the X‐ray powder data by simulated annealing [P21/c, Z = 4, a = 6.71689(9) Å, b = 7.11774(11) Å, c = 8.66997(13) Å, β = 128.0063(7)°, V = 326.605(8) Å3, Rp = 0.010, Rwp = 0.015, RF = 0.030]. During dehydration, the structure of Sr(PO3F)·H2O collapses along [100] from a layered arrangement into a framework structure, accompanied by a change of the coordination number of the Sr2+ ions from eight to nine. The magic‐angle spinning (MAS) NMR and vibrational spectroscopy data of both phases are discussed. The dehydration of Sr(PO3F)·H2O yields Sr(PO3F) by a topotactic reaction. The crystal structures of both solids were elucidated by X‐ray diffraction methods, and the presence of P–F bonds was confirmed by magic‐angle spinning (MAS) NMR and IR spectroscopy.