Cyclic (alkyl) (amino)carbenes (CAACs) are highly nucleophilic and electrophilic species. By utilizing these properties, neutral mono- and di-nuclear coinage metal complexes have been stabilized and represent the first complexes of their kind. These complexes are readily available by one-electron reduction from the corresponding (CAAC)₂Metal⁺X⁻ and (CAAC)Metal chloride complexes, respectively. The (CAAC)₂M⁰ complexes have been studied by X-ray diffraction and electron paramagnetic resonance, demonstrating that the additional electron is located on both the metal and ligand. In addition to synthesizing the diamagnetic (CAAC)M-M(CAAC) complexes, interesting reactivity has been shown by the addition of alkynes, alkenes, CO₂, P₄, isocyanides and Fe(CO)₅ to the dimeric complexes. Attempts to isolate the larger neutral trinuclear gold complex were unsuccessful, but led to the isolation of the mixed valence Au(0)/Au(I)/Au(0) complex supported by three CAAC ligands, which proved to be a catalyst for the carbonylation of amines under mild conditions

An expanded family of ruthenium-based metathesis catalysts bearing cyclic alkyl amino carbene (CAAC) ligands was prepared. These catalysts exhibited exceptional activity in the ethenolysis of the seed-oil derivative methyl oleate. In many cases, catalyst turnover numbers (TONs) of more than 100,000 were achieved, at a catalyst loading of only 3 ppm. Remarkably, the most active catalyst system was able to achieve a TON of 340,000, at a catalyst loading of only 1 ppm. This is the first time a series of metathesis catalysts has exhibited such high performance in cross-metathesis reactions employing ethylene gas, with activities sufficient to render ethenolysis applicable to the industrial-scale production of linear α-olefins (LAOs) and other terminal-olefin products.