Karel Lutar

The First Organoxenon(IV) Compound: Pentafluorophenyldifluoroxenonium(IV) Tetrafluoroborate.

Xenon(IV) - carbon bonding has been realized for the first time in the product formed from the reaction of XeF(4) with C(6)F(5)BF(2) in CH(2)Cl(2) at -55 degrees C [Eq. (1)]. [C(6)F(5)XeF(2)][BF(4)] is a strong oxidative fluorinating agent. This xenon(IV) compound fluorinates (C(6)F(5))(3)P to (C(6)F(5))(3)PF(2), C(6)F(5)I to C(6)F(5)IF(2), and I(2) to IF(5). In all cases, [C(6)F(5)Xe][BF(4)] was obtained as a by-product.

KrF2/MnF4 adducts from KrF2/MnF2 interaction in HF as a route to high purity MnF4

Abstract In the system KrF2—MnF2—HF two new adducts, 2KrF2·MnF4 and KrF2·MnF4 have been synthesized. The 2 : 1 adduct decomposes in a dynamic vacuum at −45°C yielding KrF2 and the 1 : 1 adduct, which is stable in a dynamic vacuum up to −25°C. KrF2·MnF4 decomposes further at room temperature to krypton, fluorine, krypton difluoride and manganese tetrafluoride. This reaction is a useful synthetic route for the preparation of pure manganese tetrafluoride.

SYNTHESES, INFRARED AND RAMAN SPECTRA OF RARE EARTH (III) FLUOROARSENATES(V)

Abstract Rare earth trifluorides (LnF 3 ) dissolve in anhydrous hydrogen (aHF) acidified with AsF 5 at room temperature forming stable solutions of solvated rare earth cations Ln(HF) 3− N and AsF − 6 anions. After the excess of AsF 5 and aHF are pumped away at room temperature La(AsF 6 ) 3 , LnF(AsF 6 ) 2 with Ln-Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Y and Ln 2 F 3 (AsF 6 ) 3 with LnTm, Yb and Lu are isolated, indicating the decreasing stability of Ln(AsF 6 ) 3 and LnF(AsF 6 ) 2 along the series of rare earth metals. This behaviour perfectly reflects the reduced fluorobasicity of rare earth trifluorides along the series. In some selected cases (LnLa, Nd, Sm and Tm) the isolation of Ln(AsF 6 3 compounds was performed at lower temperatures (263–233 K). The vibrational spectra of all isolated rare earth(III) fluoroarsenates(V) show that deformed AsF 6 octahedra are present, indicating a covalent contribution to the fluorine bridges between LnF 3 and AsF 5 .

Die erste Organoxenon(IV)-Verbindung: Pentafluorphenyldifluorxenonium(IV)-tetrafluoroborat

Eine Xenon(IV)-Kohlenstoff-Bindung konnte erstmals durch Umsetzung von XeF4 mit C6F5BF2 bei −55 °C in CH2Cl2 realisiert werden [Gl. (1)]. Das Produkt, [C6F5XeF2][BF4], ist ein starkes oxidatives Fluorierungsmittel und fluoriert (C6F5)3P zu (C6F5)3PF2, C6F5I zu C6F5IF2 und I2 zu IF5. Als Coprodukt wird dabei [C6F5Xe][BF4] erhalten.

A general method for the synthesis of polymeric binary flurides exemplified by AgF3, NiF4, RuF4, and OsF4

Fluride-ion capture from their anion relatives in anhydrous hydrogen fluoride solution by strong fluoride ion acceptors such as AsF5 provides a general approach to the synthesis of polymeric binary fluorides and is particularly advantageous in the synthesis of highest-oxidation-state transition metal polymeric fluorides.

On the photosynthesis of dioxygen(1+) hexafluoroarsenate in the systems O2-F2-AsF5, OF2-AsF5 and O2-OF2-AsF5

Abstract The photochemical reactions in the systems O 2 -F 2 -AsF 5 , OF 2 -AsF 5 and O 2 -OF 2 -AsF 5 , yielding O 2 AsF 6 as the reaction product were investigated. The influence of the mole ratio of the reactants upon the rate of formation of O 2 AsF 6 was studied and a reaction mechanism is suggested which is based on the formation of O 2 F· radicals. Regarding the preparation of O 2 AsF 6 , the best results were obtained using the system O 2 -F 2 -AsF 5 with the mole ratio 1:1-1.5:1.

On the synthesis of chlorine pentafluoride

Abstract The reaction between chlorine trifluoride and elemental fluorine was studied in order to find the optimal reaction conditions for the synthesis of chlorine pantafluoride. It has been found that nickel difluoride is a very effective catalyst for the mentioned reaction. The obtained results are expressed as space-time-yield of chlorine pentafluoride.

Syntheses and some properties of binary fluorides of silver, copper and nickel

Abstract Thermally unstable highest-oxidation-state transition metal polymeric fluorides (e.g. AgF 3 , NiF 4 ) are precipitated from anhydrous hydrogen fluoride (AHF) solutions of their salts by addition of fluoroacids (A) such as BF 3 , PF 5 or AsF 5 [1]: MF x y− + yA → MF (x−y) + yAF − . Red, diamagnetic AgF 3 precipitated by AsF 5 from AHF solutions of AgF 4 − salts is reduced with excess of AsF 5 by following equation: AgF 3 + AsF 5 → AgFAsF 6 + 1/2F 2 . While such reduction does not occur with BF 3 this acid is therefore preferred for the preparation of stoichiometric AgF 3 . Silver trifluoride is thermodinamically unstable and loses F 2 in contact with AHF according to the equation: 3AgF 3 → Ag 3 F 8 + 1/2F 2 . The formation of Ag 3 F 8 by the interaction of one mole of Ag(II) and two moles of Ag(III) confirmed that the material formed in the degradation of AgF 3 is a mixed valence material Ag(II)Ag(III) 2 F 8 . Interaction of AgF + with AuF 4 − (1:1) in AHF yields maroon Ag(II)Ag(III)F 5 . Silver trifluoride is isostructural with AuF 3 . Its powerful oxidizing properties are in accord with the tight binding of its valence shell d orbital electrons. CuF 6 3− salts interact quantitavely with liquid AHF already at −60° yielding bright red CuF 3 : CuF 6 3− + 3xHF → CuF 3 + 3F(HF) x − . The oxidizing properties of above-mentioned fluorides will be discussed.

On the reactions with krypton difluoride

Abstract Krypton difluoride is a more powerful oxidizing agent than elemental fluorine, in that the total bond energy of 96 kJ mole −1 , is less than that of molecular fluorine itself (155 kJ mole −1 ). Using the combination of KrF 2 with the fluoride-ion donor solvent xenon hexafluoride, it should be possible to generate salts of novel oxidation-state transition-metal fluoro-anions. With this aim, an investigation of the system MF x KrF 2 XeF 6 with MF x being AgF 2 , NIF 2 , MnF 2 , HgF 2 , FeF 2 , PdF 3 , CrF 3 etc., was commenced. During this study some new xenon(Vl) fluorometalates (e.g. XeF 5 + AgF 4 − , (Xe 2 F 11 + ) 2 NiF 2− 6 (XeF 5 + ) 2 NiF 6 2− ) were isolated and characterized, besides some already known xenon(VI) fluorometalates (e.g. XeF 5 + FeF 4 − , (Xe 2 F 11 + ) 2 MnF 6 2− , (XeF 5 + ) 2 MnF 6 2− etc.). The advantages and disadvantages of the combination KrF 2 and XeF 6 for the generation of salts with the transition metal fluoroanion in a novel oxidation state will be discussed.

A low temperature route to binary fluorides exemplified by NiF4, AgF3, RuF4, OsF4 and ReF4

Abstract The interaction between some binary fluorides and the combination of krypton difluoride and xenon hexafluoride in anhydrous hydrogen fluoride (AHF) provides an effective synthetic route to new xenon(VI) fluorometalates with each metal in a high oxidation state (e.g. (Xe 2 F + 11 ) 2 NiF 2- 6 ; (XeF + 5 AgF - 4 ). Fluoride-ion capture from such high oxidation-state-metal anions of AHF solution by strong fluoride ion acceptors (e.g. AsF 5 ) provides a general approach to the synthesis of polymeric and (in AHF) insoluble binary fluorides. This is particularly advantageous in the synthesis of thermally unstable highest-oxidation-state transition metal polymeric fluorides (e.g. NiF 4 , AgF 3 ). AgF 3 prepared in this way is a bright red diamagnetic solid apparently isostructural with AuF 3 . The hexagonal unit cells are: AgF 3 : a 0 , 5.088(10); c 0 , 15.43(3) A; V, 346 A 3 ; Auf 3 ; a 0 , 5.149(2); c 0 , 16.26 (1) A; V 373 A 3 , the AgF 3 formula unit being 4.5 A 3 smaller than for AuF 3 . These structural features imply that the d z 2 electron pair of Ag(III) is highly contracted and in conformity with its chemistry, tightly bound. Less powerfully oxidizing binary fluorides have also been made by this new approach and include RuF 4 , OsF 4 and ReF 4 , all of which have structures related to that of PdF 4 .