Noble gas–selenium molecular species: A theoretical investigation of FNgSe− (Ng = He–Xe)

MP2 and coupled-cluster calculations were performed to investigate the structure, stability, and properties of the noble gas anions FNgSe− (Ng = He–Xe). Similar to the recently investigated congeners FNgO− and FNgS−, with the only exception of FNeSe−, all these species reside into energy minima on the singlet surface. The heaviest FKrSe− and FXeSe− are also protected by sizable barriers with respect to FSe− + Ng and F− + Ng + Se(3P). They are therefore the first predicted examples of metastable krypton–selenium and xenon–selenium molecular species. The lightest FHeSe− and FArSe− are instead kinetically unstable rather than metastable.