CHM 401

 

Crystal Field Theory or Ligand Field Theory

An ionic approach to understanding bonding in transition metal complexes

Consider the Oh case : what is the effect of the negative electron density from the ligands on the energies of the valence (d) orbitals

Δo = 10Dq = Crystal Field Splitting parameter or Ligand Field parameter

Occupation of the t2g orbitals gives a little extra stabilization of the complex

Ligand Field Stabilization Energy (LFSE)

d electron
configuration
Crystal Field
configuration
LFSE
number of
unpaired spins
d1
t2g1
–4Dq
1
d2
t2g2
–8Dq
2
d3
t2g3
–12Dq
3
d4
t2g4
–16Dq + P
2 (ls)
d4
t2g3eg1
–6Dq
4 (hs)
d5
t2g5
–20Dq + 2P
1 (ls)
d5
t2g3eg2
0
5 (hs)
d6
t2g6
–24Dq + 2P
0 (ls)
d6
t2g4eg2
–4Dq
4 (hs)
d7
t2g6eg1
–18Dq+ P
1 (ls)
d7
t2g5eg2
–8Dq
3 (hs)
d8
t2g6eg2
–12Dq
2
d9
t2g6eg3
–6Dq
1
d10
t2g6eg4
0
0

P = spin pairing energy

hs = high spin

ls = low spin