Question

Discuss the probable mechanisms of the following reaction and also speculate on why this reaction is rather slow. For each of the following electron transfer reactions, speculate whether the mechanism is outer-sphere or inner sphere. Explain your reasoning.

6, 7 a and 7b

Answer 1

Hello!

For Question 6: The Mechanism may be outer sphere electron transfer, the event that occurs between chemical species remain separate and intact before, during, and after the ET event. In contrast, for inner sphere electron transfer the participating redox sites undergoing ET become connected by a chemical bridge. Because the ET in outer sphere electron transfer occurs between two non-connected species, the electron is forced to move through space from one redox center to the other.

other example of OSET:

[MnO₄]^? + [Mn*O₄]^2? ? [MnO₄]^2? + [Mn*O₄]^?

example of ISET:

[CoCl(NH₃)₅]²⁺ + [Cr(H₂O)₆]²⁺ ? [Co(NH₃)₅(H₂O)]²⁺ + [CrCl(H₂O)₅]²⁺

About the rate of the reaction, If you look for the rate constants you find that for Co complexes the constant is small (10E-9), this complex may be predominant in the rate law of this reaction and therefore occurs slow.

Some rate constants (M-1 s-1) > 106 106 All but the last of these is "easily" explained! Note: All these rxns involve at least one d6 or d3 (substitutionally inert) complex.