Interaction of Ag+ salts in anhydrous liquid hydrogen fluoride, aHF, with AgF4- salts gives amorphous red-brown diamagnetic AgIAgIIIF4, which transforms exothermally to brown, paramagnetic, microcrystalline AgIIF2 below 0°C. AgIAuIIIF4 prepared from Ag+ and AuF4- in aHF has a tetragonal unit cell and a KBrF4 type lattice, with a = 5.788(1) Å, c = 10.806(2) Å, and Z = 4. Blue-green AgIIFAsF6 disproportionates in aHF (in the absence of F- acceptors) to colorless AgIAsF6 and a black pseudotrifluoride, (AgIIF+)2AgIIIF4 -AsF6-. The latter and other (AgF)2AgF4MF6 salts are also generated by oxidation of AgF2 or AgF+ salts in aHF with F2 or in solutions of O2+MF6- salts (M = As, Sb, Pt, Au, Ru). Single crystals of (AgF)2AgF4AsF6 were grown from an AgFAsF6/AsF5 solution in aHF standing over AgF2 or AgFBF4, with F2 as the oxidant. They are monoclinic, P2/c, at 20°C, with a = 5.6045(6) Å, b = 5.2567(6) Å, c = 7.8061(8) Å, β = 96.594(9)°, and Z = 1. The structure consists of (AgF)nn+ chains (F-Ag-F = 180°, Ag-F-Ag = 153.9(11)°, Ag-F = 2.003(4) Å), parallel to c, that enclose stacks of alternating AgF4- and AsF6-, each anion making bridging contact with four Ag(II) cations of the four surrounding chains "caging" them. There is no registry between the ordered array in one "cage" and that in any neighboring "cage". The F-ligand anion bridges between the anions and, with the Ag(II) of the chains, generates a trifluoride-like structure. (AgF)2AgF4AsF6 [like other (AgF)nn+ salts] is a temperature-independent paramagnet except for a Curie "tail" below 50 K.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry