Two Amphoteric Silver Carbene Clusters.

Two highly labile silver carbene cluster complexes are described, which are unique in that they mark the transition point at which the carbene center transmutes from a fairly common NHC-like nucleophilic behavior to an electrophilic character befitting reactive silver carbene intermediates of relevance in various catalytic transformations. This amphoteric character is the distinguishing attribute of a μ-bridged donor/donor carbene entity that connects two silver atoms of triangular or tetrahedral metallic core units.