doi.org/10.26434/chemrxiv.7092263.v1 Xenon Trioxide Adducts of O-Donor Ligands; [(CH3)2CO]3XeO3, [(CH3)2SO]3(XeO3)2, (C5H5NO)3(XeO3)2, and [(C6H5)3PO]2XeO3 Katherine Marczenko, James Goettel, Gary Schrobilgen Submitted date: 15/09/2018 • Posted date: 18/09/2018 Licence: CC BY-NC-ND 4.0 Citation information: Marczenko, Katherine; Goettel, James; Schrobilgen, Gary (2018): Xenon Trioxide Adducts of O-Donor Ligands; [(CH3)2CO]3XeO3, [(CH3)2SO]3(XeO3)2, (C5H5NO)3(XeO3)2, and [(C6H5)3PO]2XeO3. ChemRxiv. Preprint. Oxygen coordination to the Xe(VI) atom of XeO was observed in its adducts with triphenylphosphine oxide, 3 dimethylsulfoxide, pyridine-N-oxide, and acetone. The crystalline adducts were characterized by low-temperature, single-crystal X-ray diffraction and Raman spectroscopy. Unlike solid XeO , which 3 detonates when mechanically or thermally shocked, the solid [(C H ) PO] XeO , [(CH ) SO] (XeO ) , and 6 5 3 2 3 3 2 3 3 2 (C H NO) (XeO ) adducts are insensitive to mechanical shock, but undergo rapid deflagration when ignited 5 5 3 3 2 by a flame. Both [(C H ) PO] XeO and (C H NO) (XeO ) are air-stable whereas [(CH ) SO] (XeO ) 6 5 3 2 3 5 5 3 3 2 3 2 3 3 2 slowly decomposes over several days and [(CH ) CO] XeO undergoes adduct dissociation at room 3 2 3 3 temperature. The xenon coordination sphere of [(C H ) PO] XeO is a distorted square pyramid which 6 5 3 2 3 provides the first example of a five-coordinate XeO adduct. The xenon coordination spheres of the remaining 3 adducts are distorted octahedra comprised of three Xe---O secondary contacts that are approximately trans to the primary Xe–O bonds of XeO . Quantum-chemical calculations were used to assess the Xe---O adduct 3 bonds, which are predominantly electrostatic σ-hole bonds between the nucleophilic oxygen atoms of the bases and the σ-holes of the xenon atoms. File list (2) ChemRxiv_Sept_15_2018.pdf (1.12 MiB) view on ChemRxiv download file Supporting_Information_O-Base_Adducts_Sept_15_2018... (2.90 MiB) view on ChemRxiv download file FULL PAPER Xenon Trioxide Adducts of O-Donor Ligands; [(CH3)2CO]3XeO3, [(CH3)2SO]3(XeO3)2, (C5H5NO)3(XeO3)2, and [(C6H5)3PO]2XeO3 Katherine M. Marczenko,[a,b] James T. Goettel,[a,b] and Gary J. Schrobilgen*[b] Dedication ((optional)) Abstract: Oxygen coordination to the Xe(VI) atom of XeO3 was observed for the N-coordinated pyridine and pyridinium salt [7] [8] observed in its adducts with triphenylphosphine oxide, adducts and nitrile adducts of XeO3. In the case of dimethylsulfoxide, pyridine-N-oxide, and acetone. The crystalline (CH2CH2O)5XeO3, the σ-bonding interactions that occur between adducts were characterized by low-temperature, single-crystal X-ray the electrophilic xenon atom and the five nucleophilic oxygen diffraction and Raman spectroscopy. Unlike solid XeO3, which atoms of the crown ether ligand result in a xenon coordination detonates when mechanically or thermally shocked, the solid number of 8, the highest coordination number observed thus far VI [5] [(C6H5)3PO]2XeO3, [(CH3)2SO]3(XeO3)2, and (C5H5NO)3(XeO3)2 for Xe in an XeO3 adduct. Prior to the present study, there adducts are insensitive to mechanical shock, but undergo rapid were no examples in which the number of secondary bonds with deflagration when ignited by a flame. Both [(C6H5)3PO]2XeO3 and the xenon atom of XeO3 was less than three. [5] (C5H5NO)3(XeO3)2 are air-stable whereas [(CH3)2SO]3(XeO3)2 slowly The 15-crown-5 adduct of XeO3, (CH2CH2O)5XeO3, is decomposes over several days and [(CH3)2CO]3XeO3 undergoes thus far the only structurally documented example of XeO3 adduct dissociation at room temperature. The xenon coordination coordinated to an organic oxygen base. Although early studies sphere of [(C6H5)3PO]2XeO3 is a distorted square pyramid which showed that primary and secondary alcohols quantitatively [1] provides the first example of a five-coordinate XeO3 adduct. The oxidized, XeO3 does not oxidize pure t-butanol, but dissolves xenon coordination spheres of the remaining adducts are distorted to form solutions which are stable for up to six weeks.[2] octahedra comprised of three Xe---O secondary contacts that are Titrations of these solutions with M[t-BuO] (M = K or Rb) yielded approximately trans to the primary Xe–O bonds of XeO3. Quantum- shock-insensitive precipitates having short-term stabilities whose chemical calculations were used to assess the Xe---O adduct bonds, formula weights suggested the formation of M[t-BuO–XeO3]t- which are predominantly electrostatic σ-hole bonds between the BuOH. Structural characterizations of the species isolated and nucleophilic oxygen atoms of the bases and the σ-holes of the xenon described in the latter study have not been forthcoming. atoms. In the present study, the syntheses and structural characterizations of XeO3 coordination complexes of several E– O bonded ligands (E = C, S, N, P) provide further insights into the Lewis acid behavior of XeO3. The complexes have been Introduction characterized in the solid-state by low-temperature, single- crystal X-ray diffraction, and Raman spectroscopy, and by gas- Xenon trioxide is a strong oxidant that rapidly oxidizes primary phase quantum-chemical calculations, which have been used to [1,2] and secondary alcohols to CO2 and H2O. Solid XeO3 readily aid in the assignment of vibrational frequencies and to assess detonates when subjected to mild mechanical or thermal shock, the relative strengths of the Xe---O adduct bonds. decomposing to Xe and O2 gases with the liberation of 402 ±8 kJ –1 [3] mol of energy. In its solid-state structures, XeO3 has three short Xe---O contacts between the oxygen atoms of neighboring VI [4] Results and Discussion XeO3 molecules and the electrophilic Xe atom. The electrostatic potential of the xenon atom at and in the Syntheses vicinity of the C v-axis of XeO is positive and only slightly lower 3 3 Solid XeO detonates on contact with liquid DMSO and in energy than the three regions of maximum electrostatic 3 acetylacetone but readily dissolves in acetone without incident. potential, the σ-holes, which occur opposite to its polar-covalent Xenon trioxide is very soluble and stable in acetone for up to Xe–O double bonds.[5−7] The xenon–ligand bonds of XeO 3 several months at room temperature and its solutions have adducts are best described as predominantly electrostatic, proven useful in synthetic applications.[5] When acetone (weakly covalent) interactions between the highly electrophilic σ- solutions of XeO were allowed to evaporate at room holes of the Xe atom and the nucleophilic region of the 3 temperature, solid, unsolvated XeO was recovered. Slow electronegative ligand atom.[5,7,8] Secondary bonding interactions 3 cooling of these solutions from 20 to −78 °C resulted in the occur approximately trans to the three primary Xe–O bonds, as formation of clear, colorless, block-shaped crystals of [(CH3)2CO]3XeO3 (1) (eq 1) which were stored at −78 °C to prevent acetone loss due to adduct dissociation. The adduct [a] Both authors contributed equally. readily dissociated when slowly warmed to room temperature [b] K. M. Marczenko, Dr. J. T. Goettel, Prof. G. J. Schrobilgen Department of Chemistry, McMaster University under dynamic vacuum to give solid XeO3. However, when Hamilton, ON L8S 4M1 (Canada) warmed to room temperature under ca. 1 atm of dry N2, the Email: [email protected] adduct dissociated to give a solution of XeO3 in acetone. Supporting information and the ORCID identification number(s) for −78 °C the authors of this article can be found under: 3(CH3)2CO + XeO3 acetone [(CH3)2CO]3XeO3 (1) FULL PAPER An aqueous solution containing a 1:6 molar ratio of upon warming to room temperature, at no point during the XeO3:HF was mixed with DMSO at room temperature. Slow synthesis, Raman spectral acquisition, crystal isolation, and X- evaporation of the mixture yielded large, plate-shaped crystals of ray structure determination did the crystalline adduct detonate. [(CH3)2SO]3(XeO3)2 (2) (eq 2). The crystalline product was Crystalline samples of (2), (3), and (4) were shock-insensitive significantly less shock-sensitive than solid XeO3, but slowly but underwent rapid deflagration when ignited. As in the cases [7] decomposed at room temperature to (CH3)2SO2, Xe, and O2 (eq of the stable XeO3 N-base adducts, (C6H5N)3XeO3, (4- [7] 3) over a period of several days. (CH3)2NC5H4N)XeO3∙H2O, and the O-base adduct, [5] (CH2CH2O)5XeO3, the crystal structures of (1), (2), (3), and (4) RT 3(CH3)2SO + 2XeO3 [(CH3)2SO]3(XeO3)2 (2) lack extended ---O3Xe---O(XeO3) networks (vide infra). The HF(aq) structural units of these adducts are well isolated which also RT 3 [(CH3)2SO]3(XeO3)2 3(CH3)2SO2 + 2Xe + ⁄2O2 (3) significantly diminishes their shock sensitivities. Rapid oxidation of soft Lewis bases was observed at room temperature when the Slow addition of an acetone solution of C5H5NO to solid Lewis base center is phosphorus, whereas slower oxidation o XeO3 resulted in detonation, however stable solutions of C5H5NO occurred (ca. 12 h) at low temperatures (–78 C) or over several and XeO3 in a 3:2 molar ratio (vide supra) were obtained by days at room temperature when the Lewis base center is sulfur. dissolution of the ligand in aqueous XeO3. Evaporation of the solution yielded a large, rod-shaped crystal of (C5H5NO)3(XeO3)2 X-ray Crystallography (3) (eq 3) which was insensitive to mechanical shock and was cut, A summary of X-ray crystal data and refinement results is without incident, into smaller fragments for an X-ray crystal provided in Table 1.