This document provides an introduction to crystal field theory (CFT), which models the splitting of d-orbital energies that occurs when a central metal ion is surrounded by ligands in an octahedral complex. It outlines the key assumptions of CFT, including that the metal-ligand bond is ionic and the interactions between the metal d-electrons and ligand electrons are entirely repulsive. It then describes how the d-orbital degeneracy is removed in an octahedral complex, with the t2g orbitals having lower energy than the eg orbitals. Finally, it discusses the crystal field stabilization energy formula and how it can be used to predict whether complexes will be high or low spin.

1. Shri Shivaji Education Society Amravati’s
J.D.Patil Sangludkar Mahavidyalaya,
Daryapur.
CRYSTAL FIELD
THEORY
Mr.Rahul G.Sawarkar
M.Sc.(Chem) SET,GATE.

2. Contents
Introduction
Assumption of CFT
Shapes of d – orbital
Splitting in octahedral complex
CFSE formula
Electronic distribution and CFSE of High Spin & Low
Spin complexes
Applications
References.

3. Introduction
What is Coordination Compound ?
What is Double salt ?
What is Complex?
What is Ligand ?
What is CMI?

4. Assumptions of CFT
4
This theory considers a complex as a combination of a central ion
surrounded by other ions or molecules with electrical dipoles called
ligands.
The bond between the metal and the ligand is purely ionic.
The interaction between the electrons of the cation and those of the
ligands is entirely repulsive. These repulsive forces are responsible for the
splitting of the d - orbitals of metal cation .
The crystal field theory does not consider any overlapping between metal
orbitals and orbitals .
The d- orbitals which are degenerate in a free metal ion have their
degeneracy destroyed by the approach of ligands during the formation
of complex .

5. dx2-y2 dz2
dxy dxz dyz
X
Y Z
X
Y
X
Z
Y
Z
X
d - orbitals
Axial
Non-axial

6. ligands approach along x, y, z axes
(-) Ligands attracted to (+)
metal ion; provides stability
Octahedral Crystal Field
d orbital e-’s repulsed by (–)
ligands; increases d orbital
potential energy
+
-
- -
-
-
-
Crystal Field Theory

7. --------------------------------------------
dxy dyz dzx dx2-
y2 dz2
Degenerate d orbitals
dxy dyz dzx dx2-
y2 dz2
Hypothetical
Degenerate d orbitals
eg
t2g
Bary Cente
dxy dyz
dzx
dx2-y2
dz2
---------
---------
Splitting in octahedral complex
+ 0.6 ∆o
- 0.4 ∆o
E
d1
(t2g)1 (eg)0

8. --------------------------------------------
dxy dyz dzx dx2-
y2 dz2
Degenerate d orbitals
dxy dyz dzx dx2-
y2 dz2
Hypothetical
Degenerate d orbitals
eg
t2g
Bary Cente
dxy dyz
dzx
dx2-y2
dz2
---------
---------
Splitting in octahedral complex
+ 0.6 ∆o
- 0.4 ∆o
d4
E
(t2g)3 (eg)1 (t2g)4 (eg)0

9. --------------------------------------------
dxy dyz dzx dx2-
y2 dz2
Degenerate d orbitals
dxy dyz dzx dx2-
y2 dz2
Hypothetical
Degenerate d orbitals
eg
t2g
Bary Cente
dxy dyz
dzx
dx2-y2
dz2
---------
---------
Splitting in octahedral complex
+ 0.6 ∆o
- 0.4 ∆o
d8
E
(t2g)6 (eg)2 (t2g)6 (eg)2

10. Crystal Field Stabilization Theory
CFSE = ( - 0.4 x No. of electron + 0.6 x No. of electron ) ∆o + P.E.
in t2g in eg

11. System
High Spin Low spin
Electronic
Distribution
CFSE Electronic
Distribution
CFSE
d1 (t2g)1 (eg)0 0.4 ∆o (t2g)1 (eg)0 0.4 ∆o
d2 (t2g)2 (eg)0 0.8 ∆o (t2g)2 (eg)0 0.8 ∆o
d3 (t2g)3 (eg)0 1.2 ∆o (t2g)3 (eg)0 1.2 ∆o
d4 (t2g)3 (eg)1 0.6 ∆o (t2g)4 (eg)0 1.6 ∆o
d5 (t2g)3 (eg)2 0.0 ∆o (t2g)5 (eg)0 2.0 ∆o
d6 (t2g)4 (eg)2 0.4 ∆o (t2g)6 (eg)0 2.4 ∆o
d7 (t2g)5 (eg)2 0.8 ∆o (t2g)6 (eg)1 1.8 ∆o
d8 (t2g)6 (eg)2 1.2 ∆o (t2g)6 (eg)2 1.2 ∆o
d9 (t2g)6 (eg)3 0.6 ∆o (t2g)6 (eg)3 0.6 ∆o
d10 (t2g)6 (eg)4 0.0 ∆o (t2g)6 (eg)4 0.0 ∆o

12. 1. To explain deviation that occur in the heat of
formation of transition metal .
2. To predict whether the resultant complex will be
high spin or low spin and hence stereo chemical
preference is useful .
3. To explain deviation that occur in the lattice
energy of the divalent , trivalent metal halides .
Applications