Noble gas–sulfur anions: A theoretical investigation of FNgS− (Ng = He, Ar, Kr, Xe)

MP2, coupled-cluster, and multireference–CI calculations were performed to investigate the structure, stability, and properties of the noble gas anions FNgS− (Ng = He, Ar, Kr, Xe). Similar to the recently investigated FNgO− and FNgBN−, these species reside into deep wells on the singlet surface, protected by sizable barriers with respect to FS− + Ng and F− + Ng + S(3P). Their stability arises from the strong F−-stabilization of the elusive NgS. The lightest FHeS− and FArS− are also first predicted examples of helium–sulfur and argon–sulfur molecular species.