The radical-type chemistry of rhodium and iridium complexes with 'non-innocent' nitrido and PNN pincer ligands

In this thesis our efforts to synthesize and study group 9 nitrido and nitridyl radical complexes are described. Photolysis of rhodium and iridium azido complexes bearing bipyridine based PNNH pincer ligands allowed formation of the first two examples of isolated nitridyl radical complexes. The unique combination of the right amount of steric congestion and the redox activity of the PNNH ligand allows the formation and isolation of these bridging nitridyl species. These complexes have been characterized by (inter alia) X-ray diffraction, multinuclear NMR and IR spectroscopy, electrochemistry and mass spectrometry and supported by DFT calculations. Different ligand systems with more steric congestion give rise to different reactivity of the azido complexes, leading to proposed nitrido intermediates and follow-up reactions, such as an intramolecular reaction between an azido and the nitrido groups.
Furthermore, the chemical non-innocence of the bipyridine based PNNH ligand used in this thesis has been described as well. Hydrogen atom transfer reactivity from a Rh(PNNH)Cl complex leads to a partially carbon-centered radical complex that can reversibly dimerize by forming a C-C bond. Such complexes, which store an electron pair, could be applied in reversible generation of ‘ligand radicals’, rhodium(II) metallo-radicals and/or in ‘molecular batteries’.