Single-Crystal Growth and Characterization of Disilver(I) Monofluorophosphate(V), Ag2PO3F:  Crystal Structure, Thermal Behavior, Vibrational Spectroscopy, and Solid-State 19F, 31P, and 109Ag MAS NMR Spectroscopy

• Published in: Inorganic chemistry 2007-02, Vol.46 (3), p.801-808
• Main Authors: Weil, Matthias, Puchberger, Michael, Füglein, Ekkehard, Baran, Enrique J, Vannahme, Julia, Jakobsen, Hans J, Skibsted, Jørgen
• Format: Article
• Language: English
• Subjects: Crystallization; Fluorides - chemistry; Isotopes; Magnetic Resonance Spectroscopy; Molecular Structure; Phase Transition; Phosphates - chemistry; Phosphorus Isotopes; Silver - chemistry; Spectroscopy, Fourier Transform Infrared; Temperature
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic061765w

Single crystals of disilver(I) monofluorophosphate(V), Ag2PO3F (1), were obtained by slow evaporation of a diluted aqueous Ag2PO3F solution. Compound 1 adopts a new structure type and crystallizes in the monoclinic space group C2/c with eight formula units and lattice parameters of a = 9.2456(8) Å, b = 5.5854(5) Å, c = 14.7840(13) Å, and β = 90.178(2)°. The crystal structure of 1 [R(F 2 > 2σ(F 2) = 0.0268, wR(F 2 all) = 0.0665] is composed of three crystallographically independent Ag+ cations and PO3F2- anions as single building units. The oxygen environment around each of the Ag+ cations is different, with one Ag+ in distorted octahedral (d̄(Ag−O) = 2.553 Å), one in nearly rectangular (d̄(Ag−O) = 2.445 Å), and one in distorted tetrahedral (d̄(Ag−O) = 2.399 Å) coordination. Additional Ag−F contacts to more remote F atoms located at distances >2.80 Å augment the coordination polyhedra for the two latter Ag+ cations. The monofluorophosphate anion deviates slightly from C 3 v symmetry and exhibits the characteristic differences in bond lengths, with a mean of 1.510 Å for the P−O bonds and one considerably longer P−F bond of 1.575(2) Å. Compound 1 was further characterized by vibrational spectroscopy (Raman and IR) and solid-state 19F, 31P, and 109Ag MAS NMR spectroscopy. The value for the isotropic one-bond P−F coupling constant in 1 is 1 J PF = −1045 Hz. Thermal analysis (TG, DSC) revealed a reversible phase transition at 308 °C, which is very close to the decomposition range of 1. Under release of POF3, Ag4P2O7 and Ag3PO4 are the thermal decomposition products at temperatures above 450 °C.