organometalic chemistry

[Bibinou]

Hello everybody,

 

I have some problems in order to count the electrons in compound using the 18th electrons rule.

 

In the compound [(BuO)3 Mo Mo (OBu)3] I count 12 electrons (6 e- for Mo, 3 * 1e- for Metal-Metal bound, and 3 * 1e- for OBu). Is it correct?

 

In the compound W(CO)3(P Pr3)2(H2) I count 18 electrons (6 e- for W, 3 * 2e- for CO and 2*2e- for P Pr3 and 2 for the H). Is it correct?

 

Moreover, it exist exceptions to the 18-electron rule.

Why cannot V(CO)6 dimerize?

What about the compound Mo2(OSiMe3)6 and W(Me6)?

 

Why are Metallocenes [M (C5H5)2] are only known for M = V to Ni ?

 

I thank you very much for your help