Inorganic II

1. InCh3111 - Inorganic Chemistry - II
By
Dr. Madhu Thomas, Associate Professor,
Dept. of Industrial Chemistry,
College of Applied Sciences

2. Course outline
Molecular Symmetry and Group Theory
Coordination chemistry of transition metals
Electronic spectra of Coordination compounds
Preparation of coordination compounds
Bioinorganic Chemistry
Organometallic Chemistry

3. Molecular Symmetry and Group Theory
•Symmetry elements and operations
•Point groups and molecular symmetry
• Uses of point group symmetry

4. Coordination chemistry of transition metals
• History of coordination compounds
• Nomenclature
• Isomerism
• Bonding theories of d-block metal complexes
• Valence Bond Theory
• Crystal Field Theory
• Molecular Orbital Theory

5. Electronic spectra of Coordination compounds
• Spectral properties of coordination compounds
• Spectroscopic terms and their determination.
• Selection rules
• Nature of electronic transitions in complexes with d1-d9
configuration in octahedral and tetrahedral complexes
• Magneto chemistry

6. Preparation of coordination compounds
• Synthesis of coordination compounds
• Coordination compounds and the HSAB concepts
• Stability of coordination compounds: Kinetic verses thermodynamic
concepts
• Kinetics and Reaction mechanisms
• Applications of selected coordination compounds

7. Bioinorganic Chemistry
• Essential elements
• Biological metal-coordination sites
• Structures of metal coordination sites
• Metal functions in metalloproteins
• Metal ion transport and storage Roles of Na+, K+, Mg2+ , Ca2+ and iron
pumps

8. Organometallic Chemistry
• Introduction to Organometallic
• Stability of Organometallics compounds
• Structure and bonding in organometallic compounds
• Organometallic Reactions

9. Assessment
Continuous Assessment (50%)
Quiz, Tests, Assignments, Attendance and participation.
Attendance and participation
Final exam (50%)

10. 1.Molecular Symmetry and Group Theory

11. All Symmetrical things
are beautiful!
Symmetry – Nothing but Beauty
11

12. 12

13. 13

14. Flower arrangement of Kerala, India
14

15. Symmetric art work of my son when he
was 3 years.
15

16. Which of the following shapes would you call as
more symmetrical or beautiful? A or B
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17. If we rotate a piece of cardboard shaped like A by one third of a
turn, the result looks the same as the starting point. This kind of
operations are called Symmetry operations
17

18. Since A and A’ are indistinguishable ( not identical),
we say that the rotation is a symmetry operation of
the shape.
18

19. We Can have another symmetry operation possible in the
cardboard triangle by half a turn about an axis through a
vertex… How many such operations are possible?
Three… One through each vertex
19

20. These types of symmetry operations are called proper
rotation and is represented by the symbol C. The symbol
is given a subscript to indicate the order of rotation. One
third of the turn is called an C3 and one half of the turn
is called C2
What is the symbol of the following operation?
20

21. It is C4 …….rotation by ¼ of a turn…
What is the symmetry element for a regular Hexagon? It
is , C6 because we can turn 1/6 th of the turn to get
indistinguishable structure but not identical!
21

22. One element of symmetry may generate more than one
operation for example a C3 axis generates two
operations called C3 and C3
2
What happens if it is C3
3 ?
Gives identical structure (E), Which means that
C3
3 = E
In general Cn
n = E
22

23. Perform the different symmetry operations like C5, C5
2 C5
3 C5
4 C5
5
in the following regular pentagon
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24. Now we have seen two symmetry operations – One is Identity E and another is proper
rotation Cn. Can you think of a symmetry element which is possed by planar
molecule……The answer is a plane of symmetry represented by
Eg. H2O Molecule
It has one more reflection plane and there is one more C2 axis
24

25. What are the symmetry operations in H2O
Molecule?
• The Answer is C2, and ’
25

26. What are the symmetry operations Pyridine?
• The Answer is C2, and ’
26

27. A further element of symmetry is inversion centre
represented by the symbol i . This generates the
operation of inversion through the centre.
Draw a line from any point to the centre of the molecule and extend
to an equal distance to the other side, then if it reaches to an
equivalent point, then comes the operation of inversion.
Eg. Ethane in the staggered confirmation
27

28. Which of the following has inversion centers?
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29. Only B and D
Let’s see the example of C, which is not having inversion centre . The
operation i would take the point X to the point Y , which is certainly
not equivalent
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30. Now, we have the operations Cn, ,E and I.
There is one more symmetry operation is
called improper rotation represented by
the symbol S
Sn operation is rotation by 1/nth of a turn followed by reflection in a
plane perpendicular to the axis, which gives the indistinguishable
structure.
30

31. Eg. Ethane in the staggered conformation has
a S6 axis because it is brought to an
indistinguishable arrangement by a rotation of
1/6th of a turn followed by reflection.
31

32. IMPROPER AXIS OF ROTATION
CH4
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33. Point Groups and Group Theory
• What is a point group?
• The number and nature of the symmetry elements of a given
molecule are called its point group.
• Eg. C2, C3v , D3h, D3d , Td, Oh or Ih
• These point groups belong to the classes of C groups, D groups and
special groups
33

34. C3v point groups
eg. Ammonia molecule
The Molecule is Triagonal Pyramidal
The symmetry operations are E, C3 and 3 v
So the point group is C3v
34

35. D3h point group
eg. BCl3 molecule
• There are three C2 axis , one C3 axis and one horizontal
plane of symmetry ( h)
• Therefore the point group is D3h
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36. D3d Point Group
eg. Ethane in the staggered configuration
• There are three C2 axis
• Three fold principal axis
• Three verticle planes
• Therefore the point group is D3d
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37. Td,Oh or Ih point groups
• It possess many symmetry elements
• Td - a species with Tetrahedral Symmetry
• Oh – a species with Octahedral Symmetry
• Ih – a species with Isohedral Symmetry ( which is uncommon)
37

38. Examples of Td Point group
SiF4, [ClO4], [CoCl4 ]2,[NH4]+
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39. Examples of Oh Point group
SF6, [PF6], W(CO)6
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40. Example of Ih Point Group
[B12H12]2
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41. C2h Point Group
•Such a point group is generated by a Cn axis
and a horizontal mirror plane, h.
•eg. H2O2 Molecule
•It has a C2 axis and a horizontal plane of
symmetry.
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42. C1 Point group
eg.CHFClBr
Molecules that appear to have no symmetry at all.
 Possess the symmetry element E.
Possess one C1 axis of rotation.
42

43. C∞v Point Group
Linear molecules lacking a center of inversion, such
as heteronuclear diatomic molecules, belong to this
point group. It possess infinite number of vertical
planes.
Eg. HCl Molecule.
43

44. D∞h point group
Symmetrical diatomics (e.g.H2) and linear
polyatomics that contain a centre of symmetry .e.g.
[N3]- , possess a horizontal plane in addition to a C1
axis and an infinite number of v planes.
These species belong to the D∞h point group.
44

45. 45
Linear molecules
D  h
C ∞ v