Moderately Reactive Molecules Forming Stable Ionic Compounds with Superhalogens

An explanation of the ability of selected moderately reactive molecules to form stable systems with superhalogens (AlF4 and AlCl4) is provided on the basis of theoretical considerations supported by ab initio calculations. It is demonstrated that even the molecules possessing high ionization potentials (such as SiO2, NH3, CHCl3, CCl2F2) should form stable and strongly bound ionic compounds when combined with a properly chosen superhalogen system (acting as an oxidizing agent). The conclusion is supported by providing the structural parameters and interaction energies for the SiO2AlF4, NH3AlF4, CHCl3AlF4, CCl2F2AlF4, SiO2AlCl4, and NH3AlCl4 compounds obtained at the CCSD(T)/6-311++G(d,p)//MP2/6-311++G(d,p) level. On the other hand, the AlF4 and AlCl4 superhalogens were found to be incapable of reacting with molecules whose ionization potentials (IP) exceed 13 eV (e.g., CO2, CH4). Finally, it is demonstrated that the competition between the electron binding energy of the superhalogen system and the IP of the molecule the superhalogen is combined with is a key factor for predicting the stability of certain species.