Fluoroacid-base reactions of a room-temperature ionic liquid, 1-ethyl-3-methylimidazolium fluorohydrogenate (EMIm(HF)2.3F, EMIm = 1-ethyl-3-methylimidazolium cation), and Lewis fluoroacids (BF3, PF5, AsF5, NbF5, TaF5 and WF6) give EMIm salts of the corresponding fluorocomplex anions, EMImBF4, EMImPF6, EMImAsF6, EMImNbF6, EMImTaF6 and EMImWF7, respectively. Attempts to prepare EMImVF6 by both the acid-base reaction of EMIm(HF)2.3F with VF5 and the metathesis of EMImCl with KVF6 failed due to the strong oxidizing power of the pentavalent vanadium, whereas EMImSbF6 was successfully prepared only by the metathesis of EMImCl and KSbF6. EMImBF4, EMImSbF6, EMImNbF6, EMImTaF6 and EMImWF7 are liquids at room temperature whereas EMImPF6 and EMImAsF6 melts at around 330 K. Raman spectra of the obtained salts showed the existence of the EMIm cation and corresponding fluorocomplex anions. IR spectroscopy revealed that strong hydrogen bonds are not observed in these salts. EMImAsF6(mp 326 K) and EMImSbF6(mp 283 K) are isostructural with the previously reported EMImPF6. The melting point of the hexafluorocomplex EMIm salt decreases with the increase of the size of the anion (PF6- < AsF6- < SbF6-

SignificanceAntiferromagnets can host strong quantum fluctuations in their ground state if they combine both low dimensionality and low spin. Materials based on copper oxides (spin-1/2 ions in layered or 1D structures) are unique in optimizing the tendency to strong quantum fluctuations. As a bonus, they show extremely large magnetic interactions, which lead to interesting quantum effects at relatively high temperatures as anomalous transport properties and high-Tc superconductivity in doped systems. Obtaining similar features with other ions has been a long-standing goal. We show that silver and fluorine (which are next to copper and oxygen in the periodic table) in the commercial compound normalAnormalgnormalF2 reach the goal, paving the way for a different generation of quantum materials.

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The crystal structures of three salts, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF 4), hexafluoroniobate (EMImNbF 6) and hexafluorotantalate (EMImTaF 6), all of which form roomtemperature ionic liquids (RTILs), have been determined by low-temperature X-ray diffraction studies of their single crystals. EMImBF 4 crystallizes in the monoclinic space group P2 1 /c with a = 8.653(5) Å, b = 9.285(18) Å, c = 13.217(7) Å, β = 121.358(15) Å, V = 906.8(19) Å 3 , Z = 4 at 100 K. EMImBF 4 exhibits a unique structure wherein EMIm cations form one-dimensional pillars facing the imidazolium ring to the next ring linked by H(methylene)•••π electron interaction. The BF 4 anion also forms one-dimensional pillars along the same direction with the nearest F•••F contact distance of 3.368(3) Å. EMImNbF 6 and EMImTaF 6 are isostructural to each other and crystallize in the orthorhombic space group P2 1 2 1 2 1 : EMImNbF 6 , a =9.204(4) Å, b = 9.770(15) Å, c = 12.499(13) Å, V = 1124.0(2) Å 3 , Z = 4 at 200 K; EMImTaF 6 , a = 9.216(5) Å, b = 9.763(2) Å, c = 12.502(17) Å, V = 1124.9(17) Å 3 , Z = 4 at 200 K. In EMImNbF 6 and EMImTaF 6 , EMIm cations also form a one-dimensional pillar structure and the hexafluorocomplex anions are located in a zigzag arrangement along the same direction with the nearest F•••F distance of 3.441(12) Å. This structure (Type-B(MF 6)) is different from the Type-A(MF 6) structure previously reported for EMImPF 6 , EMImAsF 6 and EMImSbF 6. Hydrogen bonds in the Type-A(MF 6) (EMImPF 6 (333 K), EMImAsF 6 (326 K) and EMImSbF 6 (283 K)) crystal lattice are weaker than those in the Type-B(MF 6) (EMImNbF 6 (272 K) and EMImTaF 6 (275 K)) crystal lattice. This suggests that the strength of the hydrogen bond is not always a decisive and determining factor for the melting points of RTILs. The measurement of cell parameters for EMImBF 4 between 100 K and its melting point revealed that EMImBF 4 essentially preserves the same structure in this temperature range and increases its volume by only 4% due to the melting.

A combined experimental-theoretical study of silver(I) and silver(II) fluorides under high pressure is reported. For Ag, the CsCl-type structure is stable to at least 39 GPa; the overtone of the IR-active mode is seen in the Raman spectrum. Its AgF sibling is a unique compound in many ways: it is more covalent than other known difluorides, crystallizes in a layered structure, and is enormously reactive. Using X-ray diffraction and guided by theoretical calculations (density functional theory), we have been able to elucidate crystal structures of high-pressure polymorphs of AgF. The transition from ambient pressure to an unprecedented nanotubular structure takes place via an intermediate orthorhombic layered structure, which lacks an inversion center. The observed phase transitions are discussed within the broader framework of the fluorite → cotunnite → NiIn series, which has been seen for other metal difluorides.

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Black AgSO4, synthesized for the first time by a displacement reaction, differs considerably from anhydrous sulfates of its Group 11 congeners: it has a very small electronic band gap (ca. 0.2 eV) and an anomalously strong one‐dimensional antiferromagnetic ordering ( J≈10 meV per Ag), which persists up to the onset of its thermal decomposition at about 120 °C. Ag gray, O red, S yellow.