Non-heteroatom-substituted alkylidene complexes of groups 10 and 11

Gold Difluorocarbenoid Complexes: Spectroscopic and Chemical Profiling

“…Cationic gold carbene complexes can be thought as consisting of as inglet carbene fragment, the lone pair of which interacts with an orbital of appropriate symmetry of the [LAu] + unit to form as trong s-bond; p-back donation from the metal to the empty carbene p-orbital is (very) modest. [1][2][3][4] This particular bonding situation allows the exceptional electrophilicity of gold carbenes to be rationalized, which surfaces in ap lethora of catalytic transformations. [4][5][6][7] At the same time,itexplains why spectroscopic characterization and isolation of these highly reactive species in pure form proved challenging.K nown representatives have substituents at the carbene center, which are able to compensate for the largely missing stabilization that am ore strongly p-donating metal would entail ( Figure 1).…”

Two Amphoteric Silver Carbene Clusters

“…[23,24] Specifically,c omplex 1 features ad imesityl carbene unit (red) that, in itself,ishighly shielded by virtue of the twisting of the aryl rings enforced by the ortho substituents;in addition, the strongly electron-donating and massively overcrowded ancillary ligand (blue) safeguards the reactive carbene site to the maximum extent ( Figure 1). [23,24] Specifically,c omplex 1 features ad imesityl carbene unit (red) that, in itself,ishighly shielded by virtue of the twisting of the aryl rings enforced by the ortho substituents;in addition, the strongly electron-donating and massively overcrowded ancillary ligand (blue) safeguards the reactive carbene site to the maximum extent ( Figure 1).…”

“…Thep roblem is amplified by the paucity of secured experimental information on the structure and bonding of reactive silver carbenes.T ot he best of our knowledge,o nly as ingle electrophilic silver carbene complex has been characterized by spectroscopic and crystallographic means. [23,24] Specifically,c omplex 1 features ad imesityl carbene unit (red) that, in itself,ishighly shielded by virtue of the twisting of the aryl rings enforced by the ortho substituents;in addition, the strongly electron-donating and massively overcrowded ancillary ligand (blue) safeguards the reactive carbene site to the maximum extent ( Figure 1). This special design notwithstanding, complex 1 proved to be highly fragile;i tw as the least stable carbene complex amongst the Group 11 triad (Ag < Cu < Au), atrend that had already been noticed before for Fischer-type carbenes.…”

Gold Difluorocarbenoid Complexes: Spectroscopic and Chemical Profiling

“…Cationic gold carbene complexes can be thought as consisting of a singlet carbene fragment, the lone pair of which interacts with an orbital of appropriate symmetry of the [LAu] + unit to form a strong σ‐bond; π‐back donation from the metal to the empty carbene p ‐orbital is (very) modest . This particular bonding situation allows the exceptional electrophilicity of gold carbenes to be rationalized, which surfaces in a plethora of catalytic transformations .…”