Direct X-ray scattering evidence for metal-metal interactions in solution at the molecular level

The study of the aggregation of small molecules in solution induced by metallophilic interactions has been traditionally performed by spectroscopic methods through identification of chemical changes in the system. Herein we demonstrate the use of SAXS (small-angle X-ray scattering) to identify structures in solution, taking advantage of the excellent scattering intensity of heavy metals which have undergone association by metallophilic interactions. An analysis of the close relationship between solid-state and solution arrangements of a dynamic [Ag2(bisNHC)2]2+ (NHC=N-heterocyclic carbene) system, and how they are complementary to each other, is reported..We gratefully acknowledge financial support from the National Science Foundation (grant CHE-1102637), from the Center for Sustainable Materials Chemistry (L.B.F., S.G.F., and M.N.), and the Spanish Ministerio de Economía y Competitividad (“Ramón y Cajal” program (P.J.S.M.) and CTQ2011-27593).Peer Reviewe