Understanding the relationship of Molecular Orbital Theory to the fundamental tool of organometallic chemistry:

why?
 

The 18 electron rule is to organometallic chemistry whatcrystal field theory is to coordination chemistry.
 
 

method

A. With a recent inorganic Chemistry student as guide (you know who you are!), rediscover the development of the MOT diagram for octahedral ML₆ complexes where:

• L = a pi-innocent ligand (what is an example?)
• L = a pi-base ligand (what is an example?)
• L = a pi-acid ligand (and what is an example?)

B. Now start thinking about these questions:

1. why does an octahedral complex where L= CO want to have exactly 6 electrons?

2. what would the MO diagram for a square pyramidal M(CO)₅ complex look like?

3. How many electrons does the metal in the ML₅ complex want?

4. Extrapolate the above results to a tetrahedral carbonyl complex...then to a CN=7 complex...then to an CN=8 complex...

5. Can you formulate a general rule about the relationship of coordination number, metal electrons and carbonyl complex stability?

6. Why does the formulation you make in (6) above not hold true when L = ammonia or chloride?

Please prepare one written summary (one from theentire class)of your answers to thequestions and email  them to Dr. B. at her BrynMawr address: sburgmay@brynmawr.edu.