Application of electrochemical methods in the organometallic chemistry of transition metal π-complexes
ABSTRACT Polarography on both the dropping mercury and solid electrodes in aprotic solvents, electrolysis at a controlled potential, oscillopolarography, potentiometry, etc., along with non-electrochemical methods (such as e.s.r., nuclear-γ-resonance, i.r., n.m.r. spectroscopies) of a great number of organometallic transition metal π-complexes has been covered in detail. Methods and procedures are considered which may be helpful in the solution of such problems as a localization of electronic changes in a complex which may occur (a) on metal orbitals; (b) on the π-ligand orbitals, and (c) on the antibonding orbital of the metal–σ-ligand bond. The application of electrochemical methods in the solution of such problems as the relative location of the highest occupied and lowest vacant orbitals for a series of structurally similar π-complexes is discussed. The relation between the reduction potential of the LnM—σ—R bond and the pKa RH has been found; pKa values for a number of metallocenes as a C—H-type acid have been determined.