Marczenko Katherine M, Mercier Hélène P A, Schrobilgen Gary J
Department of Chemistry, McMaster University, Hamilton, Ontario, L8S 4M1, Canada.
Angew Chem Int Ed Engl. 2018 Sep 17;57(38):12448-12452. doi: 10.1002/anie.201806640. Epub 2018 Aug 20.
Crown ethers have been known for over 50 years, but no example of a complex between a noble-gas compound and a crown ether or another polydentate ligand had previously been reported. Xenon trioxide is shown to react with 15-crown-5 to form the kinetically stable (CH CH O) XeO adduct, which, in marked contrast with solid XeO , does not detonate when mechanically shocked. The crystal structure shows that the five oxygen atoms of the crown ether are coordinated to the xenon atom of XeO . The gas-phase Wiberg bond valences and indices and the empirical bond valences indicate that the Xe- - -O bonds are predominantly electrostatic and are consistent with σ-hole bonding. Mappings of the electrostatic potential (EP) onto the Hirshfeld surfaces of XeO and 15-crown-5 in (CH CH O) XeO and a detailed examination of the molecular electrostatic potential surface (MEPS) of XeO and (CH CH O) reveal regions of negative EP on the oxygen atoms of (CH CH O) and regions of high positive EP on the xenon atom, which are also in accordance with σ-hole interactions.
冠醚已为人所知五十多年了，但此前从未有过稀有气体化合物与冠醚或其他多齿配体形成配合物的例子。已证明三氧化氙与15-冠-5反应形成动力学稳定的(CH₂CH₂O)₅XeO加合物，与固态XeO₃形成鲜明对比的是，该加合物在受到机械冲击时不会爆炸。晶体结构表明，冠醚的五个氧原子与XeO₃的氙原子配位。气相Wiberg键价和键指数以及经验键价表明，Xe—O键主要是静电作用的，并且与σ-空穴键合一致。将静电势(EP)映射到(CH₂CH₂O)₅XeO中XeO₃和15-冠-5的Hirshfeld表面上，以及对XeO₃和(CH₂CH₂O)₅XeO的分子静电势表面(MEPS)进行详细研究，发现在(CH₂CH₂O)₅的氧原子上存在负EP区域，在氙原子上存在高正EP区域，这也与σ-空穴相互作用一致。
