Question

SYNTHESIS OF TRANSITION METAL COORDINATION COM 3. Ethylenediamine ("en" in short-hand notation) has two amine groups, one at each end of a two-carbon chain, NH,CH,CH,NH. Each nitrogen in NH,CH,CH_NH, has a lone pair that coordinates to the metal. Thus, one NH CH CH NH, ligand, takes up two coordina- tion sites. a) Draw and label the structures of the cis and trans isomers of Co(en),C1,CI. b) What is the coordination number for (Coſen),C1,CI? c) Determine the oxidation state of the cobalt in each of these complexes. d) What is the molecular geometry? 4. In Part 1 of this experiment, CoCl2-6H,O reacts with ammonium chloride, ammonium hydroxide, and hydrogen peroxide to produce [Co(NH3)JCl, and water. a) Write the balanced equation for this reaction. b) What is the purpose of adding the charcoal? c) To the test tube containing CoCl2-6H,O, NH,CI, and NH,OH, 3 mL of 10% H2O2 is added. Why must the H,O, be added slowly, in 1 mL portions? What is the purpose of adding the H2O2? d) What is the coordination number for CO(NH).JCI,? What is the charge on the com- plex ion? Distinguish between the complex ion and the counter ion. Determine the oxidation state of the cobalt in CoCl2 6H,O and Co(NH3).JC13. How many d-electrons does the cobalt have in (CO(NH3).JC13? 5. In Part 2 of this experiment you will synthesize Co(NH3),CICI a) Write the balanced equations for the reactions to synthesize (Co(NH),CI]Cl.. Explain the difference in the synthesis of [Co(NH3). Cl; and (Co(NH3),CI]CI. b) What property will allow you to distinguish between Co(NH3). Cl, and (Co(NH3),CIJCI ? What causes the difference? Draw the d-orbital diagrams, including the electrons, indicating the relative crystal field splitting for the two compounds. Both compounds are diamagnetic 6. In Parts 3 and 4 of this experiment you will synthesize cis- and trans-[Co(en),Cl,CI. a) Write the balanced equation for the reaction to synthesize trans-[Co(en),Cl]CI. b) What is the purpose of aerating the solution containing CoCl2 6H,O, hydrogen per- oxide, and ethylenediamine? c) What safety issues must be taken into consideration? BIRCUSSION

Answer 1

ce ! , --- Itu- CO WHE N I Trang isomer d) - cis-isomel This is octahedral Geometry. b) [co cen, az a co-ordination number cl - Mono dentate ligand en-bidentate ligan Number coordination 2/2) + 1(2) = 4+2=6 coor Number=6 c) r +062) + (-1) 2 = +1 x +3 oxidation state ts.