University of California, Los Angeles

CHEMISTRY 171: PROBLEM SET 7 (11/13/15)

1)Determine the CFSE (crystal field stabilization energy) for each of the following:

1. 2. Ru(H O)³⁺                   
   3.  

2. Explain how ?_o is affected by ?-acceptor ligands, ?-donor ligands and by ligands that don’t ?-bond

3. Calculate the crystal field stabilization energy and predict whether the following exhibit a Jahn-Teller distortion:

1. d2 octahedral and tetrahedral                              
2. d3 octahedral and tetrahedral.                            
3. d4 octahedral (consider both cases)                  
4. Ti+2 tetrahedral                                                         
5. Co+2 octahedral                                                         
6. Cu+2 octahedral                                                        
7. Cd+2 octahedral                                                         

4. Which of the following complexes obey the 18-electron rule (EAN rule)?
   1. Cu(NH )^2?, Cu(en)²⁺, Cu(CN)^3-                            

3  4                   3                      4

1. 2. Ni(NH )²⁺, Ni(CN)^2-, Ni(CO)

3  6                    4                    4

1. 3. Co(NH )^3? , CoBr^2-                                            

3  6                 4

1. 4. Fe(CN)3- , Fe(CN)4?, Fe(CO)5                     

6                      6

1. 5. Cr(NH₃ ^3? , Cr(CO)

6. Determine the number of d electrons for each of the following:

1. 1. Fe(CN)4-                                                                d. Cr(NH3)3+                    

6                                                                                         6

1. 2. Fe(H2O)3+                                                            e. Ru(NH3)3+                   

6                                                                                      6

1. 3. Co(NH3)3+                                                            f. PtCl2-                              

6                                                                          6

7. The structure of Co2(CO)8 shows that in the solid state there are two bridging carbonyl groups. Studies of Co2(CO)8 in solution have shown that the compound also exists in an unbridged form. Formulate a structure for the unbridged form in which the 18-electron rule is obeyed. Is a metal-metal bond required?

8. The complex [Ni(CN)4]-2 is diamagnetic, but [NiCl4]-2 is paramagnetic with two unpaired electrons. Likewise, [Fe(CN)6]-3 has only one unpaired electron, but [Fe(H2O)6]+3 has five.

a      Explain these experimental observations using valence bond theory.