Efficient new transformations of carbon dioxide represent an important goal in synthetic and environmental chemistry.  Seeking catalysts for such reactions, we have explored the synthesis of low-coordinate complexes of the late transition metals.  This talk will present the use of N-heterocyclic carbene ligands to support new complexes of the Group 11 metals, many of them inaccessible using phosphine ligands.  These isolable yet reactive complexes catalyze a range of reactions, including the fixation of carbon dioxide and the formation of carbon–fluorine bonds

Biomechanics is now a major area of materials research. The mechanics of fracture and other damage modes in engineering ceramic coatings on soft substrates are of special interest because of the potential for premature failures in biomechanical prostheses— dental crowns, hip replacements, etc. In this presentation we characterize contact damage modes in model layer systems that simulate the basic features of biomechanical structures (especially dental crowns), and at the same time allow direct experimental observation of the system responses during loading. We report on different fracture and deformation modes in the ceramic layers, and derive explicit analytical relations for the critical loads required to initiate these competing modes in terms of conventional materials properties (modulus, strength, toughness, hardness) and geometrical variables (layer thickness, contact radius). Particular attention is devoted to radial cracks that initiate within the coating layers—these cracks are believed to a principal cause of clinical failures. Experimental data on selected model bilayers and trilayers are used to validate the relations. Use of the results to provide a sound basis for the design of layer systems with optimal damage thresholds will be discussed.