Question

Those are three substances: Ferrocyanide (Fe(CN)64-); Ferrocenemethanol; Fe2+(aq).

The question is: Based on the understanding of Marcus Theory and how it is used to rationalize the observed rate of electron transfer for redox species, draw out the shape of the CV that will be obtained for each of the Fe(II) species.

Answer 1

R.MARCUS recognised that the electrone transfer should be adiabatic.,because electron motion should be fastened than nuclear motion. In other words electrone transfer takes place quickly ,once internuclear distances have become appropriately adjusted. For the complex that is being oxidised ,metal-ligand distances in the activated complex must generally become shorter,because of higher oxidation state that is to exist on metal upon oxidation .the complex being reduce must achieve longer metal-ligand bond distance in the activated complex,in anticipation of the lower oxidation state that develops at the metal upon reduction.

  THE POTENTIAL ENERGY CURVES FOR REACTION

The reactant initially have normal bond lengths for Fe(2) and Fe(3) , respectively and reaction correspond to motion in which Fe(2) bonds shoten and Fe(3) bonds simultaneously lengthen .the potential energy curve for the product of this symmetrical fraction is same s for reactant , the only difference being the change in role of the two Fe atoms.i have assumed that metal-ligand streching motions resemble a harmonic vibration and so have drawn them as parabolas.

The activation complex have been shown at the intersection of two curves. However ,the non crossing rulestate that molecular potential energy curves of the state of symmetry do not cross but instead split into an upper and a lower curve (as shown in figure ). the non crossing rule implies that ,if the reactants in their grund states slowly distort ,then they follow the path of minimum energy and transform into product into their ground state.