A Guide to Low?Valent Titanocene Complexes as Tunable Single?Electron Transfer Catalysts for Applications in Organic Chemistry

Low-valent titanocene catalysts are a versatile tool for organic synthesis. They promote inter- and intramolecular reactions ranging from homolytic bond cleavages to reductive umpolung additions cyclizations in single electron steps. These heavily depend on the redox potential of an situ formed titanium(III) center, which can be adjusted by choice appropriate ligands. We herein review various chiral achiral ligand-modified their reduction potentials Ep/2 obtained via cyclic voltammetry. The latter found correlate with Hammett parameters ?p cyclopentadienyl substituents pKa values corresponding acids Ti?X For selected examples, we further discuss how adjustment properties through modifications ligands lead greatly improved reaction outcomes catalyzed single-electron transfer reactions.