Question

(i) explain how they differ. b. (ii) Explain how the following reaction was used to deduce the mechanism of inner sphere electron transfer. [Co(NH,),Cl]Cr(Hd+SH,OCo(H,O)+ [Cr(HO),ci+5NH 8 marks] (i) Given the following ligands, suggest which one you would use as a chelating agent to treat an excess of Fe(III). Explain your choice. c. HS SH он HS NH2 Ci) Assuming an octahedral geometry, draw the strueture (inecluding any possible isomers) of the neutral Fe(III) complex that would be formed if it was reacted with an excess of your choice of ligand. Deprotonation of the ligand may occur upon complexation to the metal. [7 marks]

Answer 1

b. (i) inner-sphere electron transfer and outer-sphere electron transfer. They differ in the electron transfer, one involves the electron transfer within the same complex-ion, whereas the other involves the electron transfer between two complex-ions.

(ii) [Co(NH₃)₅Cl]²⁺ + [Cr(H₂O)₆]²⁺ +5H₂O ----> [(H₂O)₅Co --- Cl --- Cr(H₂O)₆]²⁺ ----> [Co(H₂O)₆]²⁺ + [Cr(H₂O)₅Cl]²⁺

c. (i) A is the preferred ligand.

Explanation: Fe-O interaction is the favorable hard(metal)-hard(ligand) interaction.

(ii) The structure of the Fe(III)-complex with the ligand A can be drawn as follows.