A facile route to 'naked' Ag+ ions enabling the coordination of the weak Lewis base Ni(CO)4.

The reaction of AgCN with two equivalents of tris(pentafluorophenyl)borane (BCF) in CH2Cl2 or ortho-difluorobenzene (oDFB) provides a straightforward access to (solvated) Ag+ salts of the weakly coordinating cyanide-bridged anion [µ-(CN)(BCF)2]- (suggested abbreviation [BCNB]). Reacting Ag[BCNB] with Ni(CO)4 yields the first structurally characterized complex in which Ni(CO)4 acts as a ligand towards a transition metal ion proving the extremely low basicity of the anion.