Neil Bartlett Memorial Lecture: In the Wake of Neil Bartlett’s Beautiful Experiment; Recent Developments in Krypton and Xenon Chemistry

Seminar | April 28 | 4-5 p.m. |  Pitzer Auditorium, 120 Latimer Hall

 Prof. Gary J. Schrobilgen, Department of Chemistry, McMaster University

 College of Chemistry

Although the highly endothermic, shock-sensitive XeVIO3 and XeVIIIO4, have been known for ca. five decades, examples of Xe(II) oxide species have only been synthesized and characterized recently. The zigzag-shaped [XeOXeOXe]2+ cation (C2h) was synthesized as its [µ-F(ReO2F3)2]– salt by reaction of ReO3F with XeF2 in anhydrous HF (aHF) at –30 oC. The bent [XeOXe]2+ cation was stabilized as its CH3CN adduct, [CH3CNXeOXeNCCH3]2+, by reaction of [FXeO---FXeF][AsF6] with CH3CN in aHF solvent and structurally characterized. Preliminary evidence for O(XeF)2 will also be presented.

Acetonitrile and XeF6 react at −40 oC in Freon-114 to form the highly endothermic and shock-sensitive F6XeNCCH3 and F6Xe(NCCH3)2·CH3CN adducts and the first examples of XeVI–N bonds. Their low-temperature (LT) X-ray structures show the Xe valence electron lone pair is stereochemically active and the adducted XeF6 molecules are among the most isolated XeF6 moieties thus far encountered in the solid state.

An extensive series of XeVI−N and XeVI−O bonded complexes of XeO3 has been synthesized and structurally characterized at LT. Unlike XeO3, many are stable at ambient temperatures and are not shock sensitive. Haloxenate(VI) anions have been little investigated. A series of kinetically stable cage anion salts, [N(C2H5)4]3[X3(XeO3)3]∙2CH3CN and [N(CH3)4]4[X4(XeO3)4] (X = Cl, Br), which have been synthesized in CH3CN, provide the first examples of Xe–Br bonds and noble-gas cage anions.

Although numerous examples of XeF2 molecules coordinated to s- and d-block cations have been structurally documented, the coordination chemistry of KrF2 was, until recently, non-existent. Among the fluorine coordinated KrF2 complexes that have been synthesized in anhydrous HF (aHF) at LT are [(KrF2)2BrOF2][AsF6], [Hg(KrF2)5][AsF6]2, [Mg(KrF2)4][AsF6]2, [XeF5][AsF6]∙KrF2 and [XeF5][AsF6]∙2KrF2. The latter are the only examples of mixed noble-gas compounds.

The fields of sulfur-nitrogen-fluorine chemistry and noble-gas chemistry have been significantly extended by the syntheses and characterizations of four new xenon-nitrogen bonded cations derived from NSF3. The XeII–N bonded adduct-cation salt, [F3SNXeF][AsF6], has provided the entry point to a significant chemistry through HF solvolysis of the coordinated NSF3 ligand and the HF catalyzed and solid-state rearrangements of [F3SNXeF]+ to give [F4S=NXe]+, [F4S=NXe---NSF3]+, and [F5SN(H)Xe]+.

 Light refreshments will be served at 3:50pm in The Coffee Lab

 seminarcoordinator-cchem@berkeley.edu, 510-643-0572