Problems: The Eighteen Electron Rule 

1: Which calculation is correct when applying the The Eighteen Electron Rule to the following structures.
(Click on the best summation.)

1a)
 
Fe0            = 8e-
(5-C5H5) = 5e-
2 x (CO)T = 4e-
C2H4         = 1e- 
                     18e-
     See answer		 Fe+            = 9e-
(5-C5H5) = 5e-
2 x (CO)T = 2e-
C2H4         = 2e- 
                     18e-
     See answer		 Fe-            = 7e-
(5-C5H5) = 1e-
2 x (CO)T = 4e-
C2H4         = 4e- 
                     16e-
     See answer		 Fe+            = 7e-
(5-C5H5) = 5e-
2 x (CO)T = 4e-
C2H4         = 2e- 
                     18e-
     See answer

1b)
 
Fe0            = 8e-
(5-C5H5) = 2e-
2 x (CO)T = 8e- 
                   18e-
   See answer		 Fe0            = 8e-
(5-C5H5) = 5e-
2 x (CO)T = 4e- 
                   17e-
   See answer		 Fe-            = 9e-
(5-C5H5) = 5e-
2 x (CO)T = 4e- 
                   18e-
   See answer		 Fe+            = 9e-
(5-C5H5) = 5e-
2 x (CO)T = 4e- 
                   18e-
   See answer

2: Which structure matches the following molecular formula? Use the Eighteen Electron Rule to predict the correct structure.
(Click on the best summation.)

2a) (C6H6)Cr(CO)3
 

2b) (5-C5H5)Fe(CO)(PPh3)Me
 

2c) Os3(CO)12
 

2d) (Pr3P)2PtBr(C6H5)