Question

3. In addition to the energy involved in readjusting the M-L bond lengths in the coordinated metal ions that serve as reactants, there are several other contributing factors to the energy of activation for an outer sphere redox reaction. Clearly identify/explain 2 of these other factors.

Answer 1

The electron transfer reaction in OSET process involves the chemical activation of precursor complex to overcome Frank-Condon Barrier. The most contributing factor in chemical activation process is bond length and bond angle adjustment. Besides this other some important contributing factors are - - i) Electronic activation to allow T * 174 transter when the G.S.configurations leach oth st * or * o* e-transter. ii) Electronic activation to accommodate the spin state change (if any) 2 Change in the electronic configuration (for on complex). in orbital (tag level) doesn't seriously affect the M-L bond length, but metal-ligand B. L is very muc sensitive to the é contiguration of o* (eg) orbital. Thus donation of tag e- from tag of reductant to an. accommodation of e-intza of oxidant is very favourable path as it leads to less reorganizing energy In on geometry , IT* obitals are exposed everywhere except vertices. This makes - IT* overlaping interaction better. Whereas, o*obilahs are projected towarch the vertices, where, ligands are positioned, this more shielded. So, 6*6* orbitals overlaping is unvourable. 2 Tans, sometimes, redwed and oxidized metal Centres have different spin-state, which will not facilates the energy favourable 17 y Tl* transition. Thus, there will be a need of spin-change state change to overcome barrier ote-transfer.