ELECTROCHEMICAL STUDY OF TRICARBONYL(ETA(6)-CYCLOOCTATETRAENE)METAL(0) COMPLEXES OF THE GROUP-6 ELEMENTS

Tricarbonyl(eta(6)-cyclooctatetraene)metal(0) complexes of the group 6 elements were prepared by using the procedures described in the liter ature with some minor modifications and identified by IR and NMR spect roscopy. Their electrochemical behavior was studied by using cyclic vo ltammetry in dichloromethane solution containing 0.1 M tetrabutylammon ium tetrafluoroborate as supporting electrolyte. Their oxidation and r eduction potentials were measured and discussed in terms of the fronti er energy levels in connection with the UV-Visible electronic absorpti on spectral data. In order to elucidate the mechanism of electrooxidat ion of the complexes, constant potential electrolysis was performed fo r one representative example, tricarbonyl(eta(6)-cyclooctatetraene)chr omium(0). The IR monitoring of the reaction showed that it is graduall y converted to hexacarbonylchromium(0) upon electrolysis at constant p otential.