Wei-Chih Shih

Bimetallic Nickel Aluminun Mediated Para-Selective Alkenylation of Pyridine: Direct Observation of η2,η1-Pyridine Ni(0)−Al(III) Intermediates Prior to C−H Bond Activation

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.

Preparation and Characterization of Amino-Linked Heterocyclic Carbene Palladium, Gold, and Silver Complexes and Their Use as Anticancer Agents That Act by Triggering Apoptotic Cell Death

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.

Expanding the Ligand Framework Diversity of Carbodicarbenes and Direct Detection of Boron Activation in the Methylation of Amines with CO2

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.

Carbodicarbenes: Unexpected π-Accepting Ability during Reactivity with Small Molecules

An investigation of carbodicarbenes, the less explored member of the carbenic complex/ligand family has yielded unexpected electronic features and concomitant reactivity. Observed 1,2-addition of E-H bonds (E = B, C, Si) across the carbone central carbon and that of the flanking N-heterocyclic carbene (NHC) fragment, combined with single-crystal X-ray studies of a model Pd complex strongly suggests a significant level of π-accepting ability at the central carbon of the NHC moiety. This feature is atypical of classic NHCs, which are strong σ-donors, with only nominal π-accepting ability. The unanticipated π-acidity is critical for engendering carbodicarbenes with reactivity more commonly observed with frustrated Lewis pairs (FLPs) rather than the more closely related NHCs and cyclic (alkyl)(amino)carbenes (CAACs).

Carbodicarbenes and their Captodative Behavior in Catalysis

That of carbones is a new family member in the class of low‐valent carbon compounds. Unlike its cousin, the conventional carbene, the carbone possesses two free electron lone pairs. In combination with their unique allene‐type structure, they possess stronger σ‐donating ability than conventional carbenes such as NHCs or CAACs. Because of this property, they have a huge potential to become a new class of ligands in organometallic chemistry and catalysis. Although carbodiphosphoranes (CDP) were initially discovered in 1961, nearly 50 years were needed to attract the attention of the chemical community with the synthesis of the carbodicarbene (CDC). This Concept paper summarizes developments over the last 10 years and future outlooks for this new class of σ‐donors, particularly carbodicarbenes.