65014-03-1Relevant academic research and scientific papers
XeOF3-, an example of an AX3YE2 valence shell electron pair repulsion arrangement; Syntheses and structural characterizations of [M][XeOF3] (M = Cs, N(CH3) 4)
Brock, David S.,Mercier, Helene P. A.,Schrobilgen, Gary J.
, p. 10935 - 10943 (2010/09/16)
The XeOF3- anion has been synthesized as its Cs + and N(CH3)4+ salts and structurally characterized in the solid state by low-temperature Raman spectroscopy and quantum-chemical calculations. Vibrational frequency assignments for [Cs][XeOF3] and [N(CH3) 4][XeOF3] were aided by 18O enrichment. The calculated anion geometry is based on a square planar AX3YE 2 valence-shell electron-pair repulsion arrangement with the longest Xe-F bond trans to the oxygen atom. The F-Xe-F angle is bent away from the oxygen atom to accommodate the greater spatial requirement of the oxygen double bond domain. The experimental vibrational frequencies and trends in their isotopic shifts are reproduced by the calculated gas-phase frequencies at several levels of theory. The XeOF3- anion of the Cs + salt is fluorine-bridged in the solid state, whereas the anion of the N(CH3)4+ salt has been shown to best approximate the gas-phase anion. Although [Cs][XeOF3] and [N(CH 3)4][XeOF3] are shock-sensitive explosives, the decomposition pathways for the anions have been inferred from their decomposition products at 20°C. The latter consist of XeF2, [Cs][XeO2F3], and [N(CH3)4][F]. Enthalpies and Gibbs free energies of reaction obtained from Born-Fajans-Haber thermochemical cycles support the proposed decomposition pathways and show that both disproportionation to XeF2, [Cs][XeO2F3], and CsF and reduction to XeF2, CsF, and O2 are favorable for [Cs][XeOF3], while only reduction to XeF2 accompanied by [N(CH3)4][F] and O2 formation are favorable for [N(CH3)4][XeOF3]. In all cases, the decomposition pathways are dominated by the lattice enthalpies of the products.
New syntheses and properties of XeO2F2, Cs+XeO2F3-, and NO2+[XeO2F3·nXeO 2F2]-
Christe, Karl O.,Wilson, William W.
, p. 3763 - 3768 (2008/10/08)
Alkali-metal nitrates and N2O5 are useful reagents for the stepwise replacement of two fluorine atoms by one oxygen atom in xenon fluorides or oxyfluorides. Thus, the reaction of an excess of XeF6 with CsNO3 yields XeOF4, FNO2, and CsXeF7 in high yield. With CsNO3 in excess, the primary products are CsXeOF5 and FNO2, and after longer reaction times some CsXeO2F3 is also formed. The reaction of CsNO3 with an excess of XeOF4 produces FNO2 and XeO2F2 in quantitative yield with a mixture of CsF and CsXeOF5 as the byproducts. Recrystallization of this CsF-CsXeOF5-XeO2F2 mixture from anhydrous HF provides a convenient synthesis for CsXeO2F3. The reaction of N2O5 with an excess of XeOF4 results in XeO2F2 and FNO2, thus providing a new safe synthesis for XeO2F2. Vibrational spectra of liquid, solid, and Ar-matrix-isolated XeO2F2 are reported. With FNO2, xenon dioxide difluoride forms an unstable NO2+[XeO2F3·nXeO 2F2]- adduct, which was characterized by Raman spectroscopy. The vibrational spectra of CsXeO2F3 were recorded and assigned. It is shown that the two oxygen atoms in XeO2F3- are cis and not trans to each other and that the Raman spectrum previously attributed to Cs+XeO2F3- is due to a Cs+[XeO2F3·nXeF2]- adduct.
