A new krypton complex - experimental and computational investigation of the krypton sulphur pentafluoride cation, [KrSF 5 ] + , in the gas phase.

The gas-phase reactions of noble gas (Ng) cations, namely Kr + and Xe + , with SF 6 were investigated experimentally by Fourier transform ion cyclotron resonance mass spectrometry and computationally using RI-MP2 and BCCD(T) methods. The study revealed a new interaction between Kr + and neutral SF 6 that gave rise to a new cationic, weakly bound complex of Kr, [KrSF 5 ] + , although the major reaction channel was dissociative electron transfer to yield SF 5 + and {Kr, F}. Experimental studies examined the formation and stability of the new species and computational studies addressed the energetics of the reaction and indicated that [KrSF 5 ] + is stable by ca. 1 kcal mol -1 . The same computational approach was used to examine the reaction of Xe + with SF 6 and showed it to be thermodynamically unfavourable by ca. 35 kcal mol -1 , confirming the non-observation of reaction in the mass spectrometry experiments. An analysis of the bonding in [KrSF 5 ] + clearly showed that it is a non-covalently bound species, while in its presumed precursor [KrSF 6 ] + a partially covalent Kr-F bond is present.