- Disproportionation of Ag(II) to Ag(I) and Ag(III) in fluoride systems and syntheses and structures of (AgF+)2AgF4-MFe6 - salts (M = As, Sb, Pt, Au, Ru)
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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) A?, c = 10.806(2) A?, 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) A?, b = 5.2567(6) A?, c = 7.8061(8) A?, 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) A?), 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.
- Shen, Ciping,Z?emva, Boris,Lucier, George M.,Graudejus, Oliver,Allman, John A.,Bartlett, Neil
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p. 4570 - 4577
(2008/10/08)
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- Vibrational Spectra and Structural Aspects of Fluorosulfites
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The Raman and infrared spectra of the fluorosulfites of K+, Rb+, Cs+, NH4+, and Me4N+ have been examined. Previous assignment of the fundamental vibrations is revised, and an ab initio study of the SO2F- anion is presented. For the pyramidal anion of symmetry Cs, distances of r(S-O) = 1.458 ? and r(S-F) = 1.698 ? have been calculated. The heat of formation of Me4NSO2F (-14.0 kcal/mol) was derived from the dissociation pressure of the salt. In addition, the lattice energy of Me4NF (159.2 kcal/mol) was calculated from a thermochemical cycle. The thermochemical data are discussed in terms of reactivity of the fluorides and stability of the fluorosulfites.
- Kornath, Andreas,Neumann, Frank,Ludwig, Ralf
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p. 5570 - 5573
(2008/10/09)
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