Diamino-carbenes are viewed as an alternative to the ubiquitous phosphine class of ligands, and are occasionally viewed as a substitute for ligands that coordinate via nitrogen. Throughout this book several classes of newly developed carbene precursors are presented. The work describes the generation and application of N-heterocyclic carbene derived metal complexes to a range of common organic transformations. This book opens with two distinct introductory reviews. The first focuses on recent developments in the generation and application of NHC ligands. The second is concerned with the area of hydrogen transfer reactions. The results and discussion section describes the successful generation of free 'pincer' type carbene moieties, their complexation with ruthenium and subsequent application to oxidation/reduction reactions. The development of a 'second generation' acac based ligand is presented in the penultimate results and discussion section. An array of functionalised carbene precursors are prepared, each possessing a masked carbene in a 1,5 relationship to a chelating oxo-substituent. The final chapters contain the experimental procedures for the compounds prepared.