Two series of electron-rich metal (Ni and Pd) complexes, namely a pyridine-coordinated tridentate NHC/amidate/ phenoxy metal complex and a tetradentate complex bearing an extra pyridyl group, were synthesized. Two carbene moieties, imidazole-based and benzimidazole-based NHCs, were also incorporated into the ligand backbones. Seven of the new complexes were structurally characterized and comparative structural analysis revealed that the tetradentate complex with a flanking pyridyl side-arm was less distorted, leading to chelation-assisted stronger NHC coordination and hence a shorter metal-carbene bond. The catalytic activities of the two sets of [a] L.