Evgeny Goreshnik

Poly[perfluorotitanate(IV)] salts of [H3O]+, Cs+, [Me4N]+, and [Ph4P]+ and about the existence of an isolated [Ti2F9]- anion in the solid state.

The increase in the size of monocations (A(+)) does not favor the formation of [Ti(2)F(9)](-) against [Ti(4)F(18)](2-) salts (with isolated [Ti(2)F(9)](-) or [Ti(4)F(18)](2-) anions, respectively) as previously proposed (Passmore, J.; et al. Angew. Chem., Int. Ed. 2005, 44, 7958-7961). The crystal structure determination of [Me(4)N](+) and [Ph(4)P](+) salts showed that both compounds are [Ti(4)F(18)](2-) salts; i.e., [Me(4)N](2)[Ti(4)F(18)] and [Ph(4)P](2)[Ti(4)F(18)] were obtained instead of [Me(4)N][Ti(2)F(9)] and [Ph(4)P][Ti(2)F(9)]. The product of the reaction of CsF with 2TiF(4) could be formulated as CsTi(2)F(9); however, instead of isolated [Ti(2)F(9)](-) anions, infinite ([Ti(2)F(9)](-))(n) double chains are present. In the case of H(3)OTi(2)F(9), a similar result was obtained. On the basis of the similarities of vibrational spectra of CsTi(2)F(9) and NF(4)Ti(2)F(9), it is also unlikely that the latter consists of isolated [Ti(2)F(9)](-) ions.

KAgF3, K2AgF4 and K3Ag2F7: important steps towards a layered antiferromagnetic fluoroargentate(II),

Crystal structure and magnetic properties of K2AgF4, related to recently studied Cs2AgF4, have been scrutinized. It crystallizes orthorhombic (Cmca No.64) with a = 6.182(3) A, b = 12.632(5) A, c = 6.436(3) A (Z = 4, V = 502.6(7) A3). K2AgF4 exhibits slightly puckered [AgF2] sheets and a compressed octahedral coordination of Ag(II) and it is not isostructural to related Cs2AgF4. Violet–coloured K2AgF4 orders ferromagnetically below 26 K. The DFT calculations reproduce semiconducting properties and ferromagnetism of K2AgF4 at the LSDA + U level but only if substantial values of Mott–Hubbard on-site electron–electron repulsion energies for Ag and F are used in calculations. We have also succeeded to solve the crystal structure of a brown KAgF3 (1D antiferromagnet below 64 K; GdFeO3–type, PnmaNo. 62, a = 6.2689(2) A, b = 8.3015(2) A, c = 6.1844(2) A, Z = 4, V = 321.84(2) A3) and to prepare K3Ag2F7, a novel KAgF3/K2AgF4 intergrowth phase and a member of the Ruddlsden–Popper KnAgFn+2 series (n = 1.5). Dark brown K3Ag2F7 crystallizes orthorhombic (K3Cu2Cl7-type, CccaNo. 68, setting 2) with a = 20.8119(14) A, b = 6.3402(4) A, c = 6.2134(4) A (Z = 4, V = 819.87(9) A3).

Largest perfluorometallate [Ti10F45]5− oligomer and polymeric ([Ti3F13]−)∞ and ([TiF5]−)∞ anions prepared as [XeF5]+ salts

Reactions between XeF2, TiF4 and UV-irradiated elemental F2 in anhydrous HF yielded XeF5TiF5 (XeF6·TiF4), [XeF5]5[Ti10F45] (XeF6·2TiF4), and [XeF5][Ti3F13] (XeF6·3TiF4) upon crystallization. [XeF5]5[Ti10F45] crystallizes in two crystal modifications at low (α-phase, 150 K) and ambient (β-phase, 296 K) temperatures. The crystal structure determination of [XeF5]5[Ti10F45] reveals the largest known discrete decameric [Ti10F45]5− anion built from ten TiF6 octahedra, sharing vertices, in the shape of a double-star. [XeF5]+ cations are completely ordered in the α-phase, while one of three crystallographically unique [XeF5]+ cations is two-fold disordered in the β-phase. The anionic part of [XeF5][Ti3F13] is built from tetrameric Ti4F20 and octameric Ti8F36 units sharing vertices and alternatively linked into ([Ti3F13]−)∞ columns. The charge balance is maintained by [XeF5]+ cations which form secondary Xe⋯F contacts with fluorine atoms of ([Ti3F13]−)∞ groups. The main structural feature of XeF5TiF5 is an infinite chain of distorted TiF6 octahedra joined by cis vertices.

Canted Antiferromagnetism in Two-Dimensional Silver(II) Bis[pentafluoridooxidotungstate(VI)]

By slow reaction between colorless AgIW2O2F9 and elemental F2 in liquid anhydrous HF, violet platelike single crystals of Ag(WOF5)2 were grown. The crystal structure of Ag(WOF5)2 consists of layers built from Ag2+ cations bridged by [WOF5]- anions and not, as previously assumed, from infinite [AgII-F]+∞ chains and [W2O2F9]- anions. A majority (97%) of the disordered AgII cations are found with square-planar coordination of F/O ligands within the same layer, and they form additional long contacts with O/F atoms originating from the neighboring layers. The remaining 3% the of Ag(II) ions are coordinated only by F atoms in a square-planar fashion. The magnetic moments of Ag2+ from the same layer are almost perfectly antiferromagnetically aligned. Weak ferromagnetic interlayer interactions cause a small tilt (∼1.5°) of the magnetic moments, resulting in canted antiferromagnetism. Because of the lowering of the symmetry of [WOF5]- in the solid state, the vibrational spectra show more bands than expected for regular C4v symmetry. The electronic spectrum of Ag(WOF5)2 is reported and analyzed.