Rhodium bis-carbene and well-defined iron complexes for hydrosilylation

Bis-benzimidazolium salts and chelate Rh(I) complexes with different N-substituents and varying bridge length were synthesized. The highly stable complexes were effective catalysts for the hydrosilylation of ketones. The systematic study revealed that the intricate interplay of heterocycle, bridge-length and N-substituents has to be considered when designing a catalyst for a certain application. The effect of solvent and anion on selectivity and activity of the complexes was closer investigated by NOESY and PGSE. The scope of a protocol for the microwave-assisted Ullman-type cross-coupling for the synthesis of 2-aryl-benzimidazoles was explored. The hydrosilylation of ketones and olefins with Fe complexes was investigated and pathways other than metal centered reactivity discovered. A new synthesis route for NHC-Fe complexes was developed and classic NHC, chelate bis-NHC, imine- and pyridyl-functionalized NHC complexes were prepared. Complexes with redox active ligands were applied as catalysts and concepts to access low valent iron complexes were investigated.