A simple and convergent synthetic strategy used to increase the diversity of the carbodicarbene ligand framework through incorporation of unsymmetrical pendant groups is reported. Structural analysis and spectroscopic studies of ligands and their Rh complexes are reported. Reactivity studies reveal carbodicarbenes as competent organocatalysts for amine methylation using CO2 as a synthon. A unique BH-activated boron-carbodicarbene complex was isolated as a reaction intermediate, providing mechanistic insight into the CO2 functionalization process.

We have presented new amino-NHC Ni-Al complex mediated para C-H bond activation for pyridine and quinolin, and isolated for the first time the intermediate structure of a bimetallic eta(2),eta(1)-pyridine nickel aluminum complex prior to its C-H activation, which serves as key evidence for bimetallic catalysis.

Transition metal complexes bearing amino linked N-heterocyclic carbenes (NHC) were prepared and evaluated for their antiproliferative activities in human cancer cells. The optimum antiproliferative activity, observed for the gold complex 3 in U-87 MG cells, was found to involve S-phase arrest of the cell cycle. The results indicate that 3 induces apoptosis through a p53-bak pathway, a finding that could serve as a new strategy to reduce the resistance of cancer cells to p53-induced apoptosis.

Treatment of [HC{(MES)N(CHCH)N(CH 2 CH 2 NHtBu}]Br • HBr (1) with an excess of NaOH afforded the organic-soluble imidazolium salt 2, [HC{(MES)N(CHCH)N(CH 2 CH 2 NHtBu}]Br, the structure of which was confirmed by X-ray crystallography. Deprotonation of 2 by NaN(SiMe 3 ) 2 yielded the thermally unstable amino-linked free carbene, 3. The molecular structure of 3 was determined by single-crystal X-ray analysis, revealing an unexpectedly close intermolecular contact associated with the carbene and amine through an N-H • • • C interaction. In contrast to compound 3, the reaction of 2 with LiN(SiMe 3 ) 2 gave the much more stable LiBr carbene adduct 3-LiBr, which serves as an effective carbene transfer agent for organoaluminum compounds to give the corresponding AlR 3 -NHC (4a, Me; 4b, Et) in high yield. X-ray diffraction studies of 4a and 4b confirmed the formation of monomeric distorted tetrahedral Al species, in which the NHC binds via conventional σ-donation of the lone pair to the electrophilic metal center. The reaction of benzaldehyde with 4a resulted in the quantitative formation of a zwitterionic species consisting of a distorted pseudotetrahedral aluminate center covalently linked to imidazolium, 5. The product 5 resulted from insertion of the carbonyl moiety into the Al-carbene group. A similar reactivity with benzaldehyde was observed in compound 6, which was independently synthesized from addition of 1,3-bis(mesityl)imidazol-2-ylidene to AlMe 3 .