Single-Crystal Growth and Characterization of Disilver(I) Monofluorophosphate(V), Ag₂PO₃F:  Crystal Structure, Thermal Behavior, Vibrational Spectroscopy, and Solid-State¹⁹F,³¹P, and¹⁰⁹Ag MAS NMR Spectroscopy

Abstract

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) A, b = 5.5854(5) A, c = 14.7840(13) A, and beta = 90.178(2) degrees. The crystal structure of 1 [R(F2 > 2sigma(F2) = 0.0268, wR(F2 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 (d(Ag-O) = 2.553 A), one in nearly rectangular (d(Ag-O) = 2.445 A), and one in distorted tetrahedral (d(Ag-O) = 2.399 A) coordination. Additional Ag-F contacts to more remote F atoms located at distances >2.80 A augment the coordination polyhedra for the two latter Ag+ cations. The monofluorophosphate anion deviates slightly from C3v symmetry and exhibits the characteristic differences in bond lengths, with a mean of 1.510 A for the P-O bonds and one considerably longer P-F bond of 1.575(2) A. 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 1JPF = -1045 Hz. Thermal analysis (TG, DSC) revealed a reversible phase transition at 308 degrees 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 degrees C.

Synthesis, Crystal Structure, and Properties of Mn(PO3F)(H2O)2

“…As has been shown for the thermal behavior of the hydrous species Ca(PO 3 F)(H 2 O) 2 , [37,38] Sr(PO 3 F)(H 2 O), [20,37] and Mg(NH 4 ) 2 ((PO 3 F)) 2 [39] or the anhydrous species Ag 2 (PO 3 F) [8] and Hg 2 (PO 3 F), [10] multi-stage decomposition mechanisms including elimination of POF 3 (for all species), H 2 O and HF (for hydrous species) were proposed for the decompositions, as substantiated by simultaneous mass spectrometric analyses of the gaseous decomposition products.…”

“…In previous studies on monofluorophosphates we reported syntheses, structure determinations, and properties of some of these compounds. In particular, we have investigated the structural effects that are caused by incorporation of the (PO 3 F) 2-anion in combination with counter cations that have closed electron shells (Sr, [6] Ba, [7] Ag, [8,9] Hg [10] ) In continuation of these studies we became interested in divalent first-row transition metal monofluorophosphates. So far, structural studies of this family of compounds had been restricted to a few members, comprising the three hydrous phases Zn(PO 3 F)(H 2 O) 2.5 , [13] Cu(PO 3 F)(H 2 O) 2 , [14] and Co(PO 3 F)(H 2 O) 3 [15] [It should be noted that compounds with composition M 2 (PO 4 )F (M = Mn, Cu, Cd) [11] or www.zaac.wiley-vch.de…”

Vibrational spectra of the layered monofluorophosphate (V), NH4Ag3(PO3F)2

“…[1,2] Although the synthesis of Ag 2 PO 3 F has been already described, [2] its crystal structure was unknown until very recently. [3] During the experiments performed to grow Ag 2 PO 3 F single crystals from aqueous AgNO 3 and (NH 4 ) 2 PO 3 F solutions, the generation of another, unknown, phase was established. Crystals of the new compound, finally identified as NH 4 Ag 3 (PO 3 F) 2 , could be obtained and its structure was eventually determined by single-crystal x-ray diffractometry after adjusting the experimental conditions.…”

NH4Ag3(PO3F)2, a layered monofluorophosphate(V) with seven different Ag sites

“…Crystallization from the remaining ®ltrate then leads to single-phase products. Although the preparation of Ag 2 PO 3 F was described a long time ago (Lange, 1929), its crystal structure was unknown until very recently (Weil et al, 2007). During single-crystal growth experiments aimed at Ag 2 PO 3 F from aqueous AgNO 3 and (NH 4 ) 2 PO 3 F solutions, crystals of NH 4 Ag 3 (PO 3 F) 2 were obtained serendipitously, and the crystal structure of this new compound is reported here.…”