Solution and Solid-State Structure of the Anion [Ag2{closo-CB11H12}4]2-

Addition of the carbene 1,3-dimesitylimidazol-2-ylidene (IMes) to a toluene solution of Ag[closo-CB11H12] results in the formation of the complex [(IMes)2Ag]2[Ag2{closo-CB11H12}4], the anionic component of which contains two silver(I) centers bridged by two carboranes in addition to one terminally bound carborane on each metal, in the solid-state. Comparison of the observed 11B{1H} NMR chemical shifts of [(IMes)2Ag]2[Ag2{closo-CB11H12}4] or Ag[closo-CB11H12] with [NBu4][closo-CB11H12] in CD2Cl2 demonstrates that the silver ion interacts significantly with the cage in solution. Theoretical investigations using the ab initio/GIAO/NMR method of [closo-CB11H12]- and Na[closo-CB11H12] as model geometries for the silver salts support experimental evidence for these Ag···{BH} interactions in solution.