Transition Metal Complex Bonding and Spectroscopy Review

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Transition Metal ComplexBonding and
SpectroscopyReview
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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
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Donor Acceptor MO Interactions
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Roles Metal d-orbitals acceptors
Ligands donorsMO Diagram in general
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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
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Example Linear shape ligands at
positions 1 and 6dz2 dx2-y2 dxy
dxz dyz11 0 0
0 0
MO Diagram
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Example Square pyramid shape ligands at
positions 1, 2, 3, 4, 5dz2 dx2-y2
dxy dxz dyz14(1/4) 4(3/4)
0 0 0
MO Diagram
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Counting d electrons Count over from Group 1A
size of positive chargeTi2VCo3
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Filling in Electrons
If gap is gt2, then need to consider high/low
spin. If gap is lt2, then it is always high spin.
MO Diagram examples
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Comparing Overall Bond Order Low spin case
Oh d6 case
Square pyramid d6 case
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Comparing Overall Bond Order High spin case
Oh d6 case
Square pyramid d6 case
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Spectroscopy 3 types of transitions 1. d-d
transitions wavelength vs. bond
strength 2. LMCT 3. MLCT
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Sigma Interaction Strength
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LMCT with Pi Donor Ligands Mainly oxides and
halides
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MLCT with Pi Acceptor Ligands and spectroscopy
CO, CN-, pyridine