Variations on N-heterocyclic carbene ligands

In the light of examinations on the variation of electronic and steric characteristics of N-heterocyclic carbene ligands (NHCs), this dissertation mainly focuses on the question whether the concepts of ‘abnormal‘ and ‘normal‘ carbene ligands can be widened to heterocyclic systems other than imidazolylidenes. In particular, the high donor strength observed in ‘abnormal‘ imidazolylidenes bears promise for generation of ligands with new characteristics. This work in detail examines the distinction between ‘normal’ and ‘abnormal’ substituted 1,2,3-triazolylidene and tetrazolylidene ligands in transition metal complexes. In particular, NMR as well as IR spectroscopy allow evaluation of the differences between both ligand types.