Model complexes FLi center dot center dot center dot CH3X center dot center dot center dot F- (X = Cl, Br, H) and FLi center dot center dot center dot Kr center dot center dot center dot F-, with a linear orientation of the F-Li, C-X and F- molecular axes, were predicted to be energetically stable. These triads exhibit a significant cooperative effect, in which the repulsive FLi center dot center dot center dot CH3X (or weakly bound FLi center dot center dot center dot CH4/Kr pair interaction) and the weakly bound CH3X/Kr center dot center dot center dot F- pair interaction is converted into a strong attractive interaction. The results are rationalized by considering the pair energies and the three-body nonadditive components of the interaction energy. (C) 2018 Elsevier B.V. All rights reserved.