Functionalized pentamethylferrocenes: Synthesis, structure, and electrochemistry

The advantageous properties of the Cp* ligand - intensified electron donation, steric bulk, and enhanced solubility in comparison to the ubiquitous Cp ligand - are finding increasing use in organometallic chemistry. A systematic evaluation of synthetic routes to pentamethylferrocene compounds with a wide range of functionalities, including carboxyl, carbonyl, aminomethyl, vinyl, ethynyl, fulvenyl, cyclopentadienylmethyl, and others is reported, Spectroscopic, structural, and electrochemical properties of such functionalized pentamethylferrocenes Fc(*/2)-R compared to those of non-methylated ferrocenes Fc-R. The electronic influence of the Cp* ligand in these unsymmetrical ferrocenes Fc(*/2)-R has been studied by cyclic voltammetry measurements, demonstrating a decrease in oxidation potential of -0.276 V in direct comparison to non-methylated ferrocenes Fc-R. (C) 1997 Elsevier Science S.A.