Crystal structure of Cs+[(XeOF4)3F]- and vibrational study of the oxygen-18-enriched [XeOF5]- and [(XeOF4)3F]- anions

Abstract

The cesium salts of the anions [XeOF5]' and [(XeOF4)3F]" have been prepared and characterized. The Raman spectra of Xe16OF5" and Xe18OFs" are consistent with a stereochemically active lone pair in the xenon valence shell that results in a distorted octahedral arrangement of five fluorines and one oxygen around xenon to give Cs symmetry. The X-ray structure of Cs+[(XeOF4)3F]" has been obtained. Crystals are cubic, space group Pa3 with a = 13.933 (7) Á and Z = 8. The structure was solved by means of Patterson and Fourier syntheses and refined by the least-squares method to R = 0.0969 and = 0.0960 for 355 reflections. The anion possesses C3 symmetry and consists of octahedra of 0=XeF4£ (E = lone electron pair; mean XeF = 1.90 (3) A; Xe=0 = 1.70 (5) A) linked through three fluorine bridges (Xe-F = 2.62 (1) A, ¿(Xe---F---Xe) = 116.5 (8)e) with the trigonally bonded fluorine positioned 0.49 A above the plane defined by the three xenon atoms. The Raman spectra of the ,60/180 isotopic isomers of [(XeOF4)3F]" and their associated coupling patterns have been interpreted on the basis of the X-ray structure.

XeOF3−, an Example of an AX3YE2 Valence Shell Electron Pair Repulsion Arrangement; Syntheses and Structural Characterizations of [M][XeOF3] (M = Cs, N(CH3)4)

“… [ N ( CH 3 ) 4 ] [ XeOF 3 ] + SO 2 → − 78 normal° C neat XeF 2 + SO 3 + [ N ( CH 3 false) 4 ] [ F ] An attempt to dissolve [Cs][XeOF 3 ] in XeOF 4 at ca. 20 °C resulted in oxygen/fluorine metathesis to give XeF 4 , XeO 2 F 2 , and [Cs][F(XeOF 4 ) m ] according to eq . [ Cs ] [ XeOF 3 ] + ( m + 1 ) XeOF 4 → 20 normal° C neat XeF 4 + XeO 2 F 2 + [ Cs ] [ F ( XeOF 4…”

“…Weak bands between 223 and 276 cm −1 in the Cs + salt are absent in the N(CH 3 ) 4 + salt. These bands are in the appropriate region and are of appropriate intensity for stretching modes associated with fluorine bridges, suggesting an oligomeric or chain structure for [Cs][XeOF 3 ]. Such long contacts most likely result in coupling between XeOF 3 − units which not only would account for the splittings of the vibrational bands but also may result in symmetry reduction and observation of the ν as (XeF 2a ) stretching mode at 498.9, 509.7, and 512.8 cm −1 which was not observed in the N(CH 3 ) 4 + salt.…”

[H(OXeF2)n][AsF6] and [FXeII(OXeIVF2)n][AsF6] (n = 1, 2): Examples of Xenon(IV) Hydroxide Fluoride and Oxide Fluoride Cations and the Crystal Structures of [F3Xe---FH][Sb2F11] and [H5F4][SbF6]·2[F3Xe---FH][Sb2F11]

“…18 The general preference for fluorine-bridge formation over oxygenbridge formation is also found in the polynuclear Xe(VI) salt, [Cs][(XeOF 4 ) 3 F]. 24,25 The only confirmed hydroxy derivatives of xenon are the perxenate anions, H 3 XeO 6 − , H 2 XeO 6 2− , and HXeO 6 3− that were observed by conventional and stopped-flow spectrophotometry in the pH ranges −0.2−2, 6−8, and 12−13, respectively. 26 The Raman spectra of aqueous alkaline perxenate solutions show the Xe(VIII) species present are octahedrally coordinated but fail to provide further structural details.…”

“…All of the aforementioned polynuclear xenon cations and the Xe 3 OF 3 + cation contain fluorine-bridged xenon atoms (the Xe 3 OF 3 + cation also contains a Xe–O–Xe bridge) . The general preference for fluorine-bridge formation over oxygen-bridge formation is also found in the polynuclear Xe(VI) salt, [Cs][(XeOF 4 ) 3 F]. , …”

Br2F7− and Br3F10−: peculiar anions showing μ2- and μ3-bridging F-atoms

“…In comparison, compounds featuring m 2 -F bridges between two nonmetal atoms are even more uncommon; examples are known for H, 26 Kr, 27,28 Xe, 29 Br, 4,30 and I, 31 as well as for several metalloid atoms: B, 32 As, 33 Sb, 34 and Si. 35 To the best of our knowledge, the m 3 -F type among nonmetals was fully established only for Xe 36 and I. 20,21 Here, we report the results of our investigations on the non-common fluorine bridging in rubidium and cesium decafluoridotribromates(III): RbBr 3 F 10 (compound 1) and CsBr 3 F 10 (compound 2), respectively, as well as in rubidium heptafluoridodibromate(III), RbBr 2 F 7 (compound 3).…”