Solvent-mediated intermolecular bonds: cation-cation and anion-anion interactions in solution showing the signature of chemical bonds

We have illustrated such behavior for the acetone solutions of [Au(C(NHMe)2)2]+ and of TCNE− in dichloromethane, where energetically stable ([Au(C(NHMe)2)2]+)2acetone4 and (TCNE−)2dichloromethane6 aggregates have been identified (although their stability is small). The Au-Au distance in the ([Au(C(NHMe)2)2]+)2acetone4 aggregate is 3.833 Å and its electronic spectrum is shifted respect to that for the isolated monomers. In the (TCNE−)2dichloromethane6 aggregates the interaction energy is very small and the TCNE−-TCNE− distance is much larger (4.760 Å). As a consequence, no shifts in the electronic spectra are found.