1. Transition Metal Complex Bonding and Spectroscopy Review

2. Bonding: Donor-Acceptor Interactions Roles of metal and ligands Making MO Diagrams for Complexes Counting d-electrons Filling in the MO Diagram High spin/Low spin cases Comparing structures for bond strength

3. Donor Acceptor MO Interactions

4. Roles: Metal d-orbitals = acceptors Ligands = donors MO Diagram in general:

5. Specific Interactions for each d orbital based on ligand position
Use Angular Overlap parameters:
--for each d-orbital, add up the interactions for all the ligands
-- the total for that orbital determines how much higher its energy gets

7. Example: Linear shape: ligands at positions 1 and 6 dz2 dx2-y2 dxy dxz dyz 1+1 0 0 0 0
MO Diagram:

8. Example: Square pyramid shape: ligands at positions 1, 2, 3, 4, 5 dz dx2-y dxy dxz dyz 1+4(1/4) 4(3/4)
MO Diagram:

9. Counting d electrons: Count over from Group 1A – size of positive charge Ti2+: V+: Co3+:

10. Filling in Electrons
If gap is >=2, then need to consider high/low spin.
If gap is <2, then it is always high spin.
MO Diagram examples:

11. Comparing Overall Bond Order: Low spin case
Oh d6 case:
Square pyramid d6 case:

12. Comparing Overall Bond Order: High spin case
Oh d6 case:
Square pyramid d6 case:

13. Spectroscopy: 3 types of transitions 1. d-d transitions wavelength vs
Spectroscopy: 3 types of transitions d-d transitions wavelength vs. bond strength LMCT MLCT

14. Sigma Interaction Strength

15. LMCT with Pi Donor Ligands: Mainly oxides and halides

16. MLCT with Pi Acceptor Ligands and spectroscopy: CO, CN-, pyridine