AgPO2F2 and Ag9(PO2F2)14: the first Ag(I) and Ag(I)/Ag(II) difluorophosphates with complex crystal structures
The reaction of AgF2 with P2O3F4 yields a mixed valence AgI/AgII difluorophosphate salt with AgI4AgII5(PO2F2)14 stoichiometry – the first Ag(II)–PO2F2 system known. This highly moisture sensitive brown solid is thermally stable up to 120 °C, which points at further feasible extension of the chemistry of Ag(II)–PO2F2 systems. The crystal structure shows a very complex bonding pattern, comprising of polymeric AgII5(PO2F2)144− anions and two types of AgI cations. One particular AgII site present in the crystal structure of Ag9(PO2F2)14 is the first known example of square pyramidal penta-coordinated Ag(II) in an oxo-ligand environment. Ag(I)PO2F2 – the product of the thermal decomposition of Ag9(PO2F2)14 – has also been characterized by thermal analysis, IR spectroscopy and X-ray powder diffraction. It has a complicated crystal structure as well, which consists of infinite 1D [AgIO4/2] chains which are linked to more complex 3D structures via OPO bridges. The PO2F2− anions bind to cations in both compounds as bidentate oxo-ligands. The terminal F atoms tend to point inside the van der Waals cavities in the crystal structure of both compounds. All important structural details of both title compounds were corroborated by DFT calculations.
- This article is part of the themed collection: Fluorine