Solution and solid-state structure of the anion [Ag(2)[closo-CB(11)H(12)](4)](2-)

Addition of the carbene 1,3-dimesitylimidazol-2-ylidene (IMes) to a toluene solution of Agcloso-CB(11)H(12)] results in the formation of the complex (IMes)(2)Ag](2)Ag(2)closo-CB(11)H(12)](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 (11)B(1)H] NMR chemical shifts of (IMes)(2)Ag](2)Ag(2)closo-CB(11)H(12)](4)] or Agcloso-CB(11)H(12)] with NBu(4)]closo-CB(11)H(12)] in CD(2)Cl(2) demonstrates that the silver ion interacts significantly with the cage in solution. Theoretical investigations using the ab initio/GIAO/NMR method of closo-CB(11)H(12)](-) and Nacloso-CB(11)H(12)] as model geometries for the silver salts support experimental evidence for these Ag...BH] interactions in solution.