Approaching monocoordination at a silver(I) cation

The recently reported bulky N-heterocyclic carbene ITr (ITr = [(HCNCPh3)(2)C:]) was found to stabilize low-coordinate Ag(I) environments. These electrophilic species were crystallographically identified as the weak solvates [(ITr) Ag(sol)](+) (sol = PhF, MesH or CH2Cl2) and as a solvent-free dimer [(ITr) Ag]2(2+). The highly electrophilic nature of the [(ITr) Ag](+) cation was further demonstrated by the calculation of a very high methyl ion affinity (MIA) and the synthesis of [(ITr) Ag(PCO)] which features substantial side-on electron donation from a P-C pi bond to Ag.