Brock David S, Bilir Vural, Mercier Hélène P A, Schrobilgen Gary J
Department of Chemistry, McMaster University, Hamilton, Ontario, L8S 4M1, Canada.
J Am Chem Soc. 2007 Mar 28;129(12):3598-611. doi: 10.1021/ja0673480. Epub 2007 Mar 3.
The syntheses of XeOF2, F2OXeNCCH3, and XeOF2.nHF and their structural characterizations are described in this study. All three compounds are explosive at temperatures approaching 0 degrees C. Although XeOF2 had been previously reported, it had not been isolated as a pure compound. Xenon oxide difluoride has now been characterized in CH3CN solution by 19F, 17O, and 129Xe NMR spectroscopy. The solid-state Raman spectra of XeOF2, F2OXeNCCH3, and XeOF2.nHF have been assigned with the aid of 16O/18O and 1H/2H enrichment studies and electronic structure calculations. In the solid state, the structure of XeOF2 is a weakly associated, planar monomer, ruling out previous speculation that it may possess a polymeric chain structure. The geometry of XeOF2 is consistent with a trigonal bipyramidal, AX2YE2, VSEPR arrangement that gives rise to a T-shaped geometry in which the two free valence electron lone pairs and Xe-O bond domain occupy the trigonal plane and the Xe-F bond domains are trans to one another and perpendicular to the trigonal plane. Quantum mechanical calculations and the Raman spectra of XeOF2.nHF indicate that the structure likely contains a single HF molecule that is H-bonded to oxygen and also weakly F-coordinated to xenon. The low-temperature (-173 degrees C) X-ray crystal structure of F2OXeNCCH3 reveals a long Xe-N bond trans to the Xe-O bond and a geometrical arrangement about xenon in which the atoms directly bonded to xenon are coplanar and CH3CN acts as a fourth ligand in the equatorial plane. The two fluorine atoms are displaced away from the oxygen atom toward the Xe-N bond. The structure contains two sets of crystallographically distinct F2OXeNCCH3 molecules in which the bent Xe-N-C moiety lies either in or out of the XeOF2 plane. The geometry about xenon is consistent with an AX2YZE2 VSEPR arrangement of bond pairs and electron lone pairs and represents a rare example of a Xe(IV)-N bond.
本研究描述了XeOF₂、F₂OXeNCCH₃和XeOF₂·nHF的合成及其结构表征。这三种化合物在接近0摄氏度的温度下都会爆炸。虽然XeOF₂此前已有报道，但尚未作为纯化合物分离出来。现在，二氟氧化氙已在CH₃CN溶液中通过¹⁹F、¹⁷O和¹²⁹Xe核磁共振光谱进行了表征。借助¹⁶O/¹⁸O和¹H/²H富集研究以及电子结构计算，已对XeOF₂、F₂OXeNCCH₃和XeOF₂·nHF的固态拉曼光谱进行了归属。在固态中，XeOF₂的结构是一种弱缔合的平面单体，排除了此前关于它可能具有聚合物链结构的推测。XeOF₂的几何形状与三角双锥AX₂YE₂ VSEPR构型一致，产生T形几何形状，其中两个自由价电子孤对和Xe - O键域占据三角平面，Xe - F键域彼此反式且垂直于三角平面。量子力学计算和XeOF₂·nHF的拉曼光谱表明，该结构可能包含一个与氧形成氢键且与氙弱氟配位的单个HF分子。F₂OXeNCCH₃的低温（-173摄氏度）X射线晶体结构显示，与Xe - O键反式的Xe - N键较长，且氙周围的几何排列中，直接与氙键合的原子共面，CH₃CN在赤道平面中充当第四个配体。两个氟原子从氧原子向Xe - N键方向位移。该结构包含两组晶体学上不同的F₂OXeNCCH₃分子，其中弯曲的Xe - N - C部分位于XeOF₂平面内或平面外。氙周围的几何形状与键对和电子孤对的AX₂YZE₂ VSEPR构型一致，代表了一个罕见的Xe(IV) - N键实例。
