Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

1. The synthesis of the complex cation [Co(en) begis with CoCl2 6 H2O. This coba

ID: 693391 • Letter: 1

Question

1. The synthesis of the complex cation [Co(en) begis with CoCl2 6 H2O. This cobalt starting material is first allowed to react with the ethylenediamine ligands and then hydrogen peroxide (H02, an oxidant) was added to the reaction mixture to produce the desired complex cation. [12 points; 6 points each] a. Determine the identity of the intermediate complex generated in the reaction (represented by the bank space in the reaction sequence shown below) after thee addition of only the ethylenediamine reactant. CoCl2(aq) + 3 en(aq) + H2O2(aq) [Co(en)J'. b. Please explain why this particular order of addition of the reagents was followed for this experiment.

Explanation / Answer

Formation of Cobalt complex

a. The reaction of cobalt chloride with ethylene diamine gave a complex,

CoCl2 + 3en ---> [Co(en)3Cl]Cl (intermediate complex)

which upon oxidation with H2O2 gave [Co(en)3]3+

b. The reagents are added in this fashion, as the firt complex formed is chloride containing complex which is oxidized in the second step. If the reagent addition is reversed, the Co(II) will get oxidized in the first step and we would end up with a different complex of formula [CoCl2(en)2]Cl and not the one we wanted to synthesize.