The SBeNg, SBNg(+), and SCNg(2+) complexes (Ng = He, Ne, Ar) have been investigated at the CASSCF and Coupled cluster level of theory. All these singlet ground-state neutrals and ions result thermochemically stable with respect to dissociation into singlet SBe and Ng, triplet SB+ and Ng, and triplet SC2+ and Ng. The only exception is SCAr2+, which should exothermically dissociate into doublet SC+ and Ar+. Thus, our calculations confirm a previous theoretical prediction [Chem. Phys. Lett. 162 (1989) 349] for the possible experimental observation of these SXNg adducts as gas phase or matrix species. (C) 2003 Elsevier B.V. All rights reserved.