1. How molecules are formed:
generally two other molecules react

2. How molecules are formed:
generally two other molecules react
What factors are involved?

3. Molecule R
Molecule S

4. Molecule R
Joined through atoms
r and s
Molecule S

5. Molecule R Molecule S Makes a supermolecule Joined through atoms
r and s
Molecule S
Makes a supermolecule

6. The possible interactions
Molecule R
Joined through atoms
r and s
Molecule S
Makes a supermolecule

7. Molecule R Molecule S Makes a supermolecule Joined through atoms
r and s
Molecule S
Lets look
at FMO
concepts L H
Makes a supermolecule

8. Orbital Control Molecule R Molecule S Joined through atoms r and s
Lets look
at FMO
concepts L H
One gets preferential interaction between frontier
orbitals closest in energy

9. If there is substantial energy difference
Molecule R
Joined through atoms
r and s
Molecule S
Lets look
at FMO
concepts L H
If there is substantial energy
difference

10. If there is substantial energy difference
Reactions are governed by charge control
Molecule R
Joined through atoms
r and s
Molecule S L H
If there is substantial energy
difference

11. Hard and Soft Acid Base Theory

12. Hard and Soft Acid Base Theory
Charge control involves small,
polarizable electron donors and
acceptors

13. Hard and Soft Acid Base Theory
Charge control involves small,
polarizable electron donors and
acceptors
Large atoms with little or no charge
almost unsovated and readily
polarized

14. Relationship between hardness and
electronegativity

15. Relationship between hardness and
electronegativity
Electronegativity = = (I + A)/2

16. Relationship between hardness and
electronegativity
Electronegativity = = (I + A)/2
Hardness = = (I-A)/2

17. Relationship between hardness and
electronegativity
I = E HOMO
Electronegativity = = (I + A)/2
Hardness = = (I-A)/2
A = E LUMO

18. Relationship between hardness and
electronegativity
I = E HOMO
Electronegativity = = (I + A)/2
Hardness = = (I-A)/2
A = E LUMO
Thus, we see the useful relationship
of hardness to FMO theory.

19. Thermochemical Data
Bond energies (Homolytic)
C-H 99 kcal/mol
C-C 83
C-O 86
C-Cl 79
C-Br 66
C-I 52

20. Thermochemical Data
Bond energies (Homolytic)
C-H 99 kcal/mol
C-C 83
C-O 86
C-Cl 79
C-Br 66
C-I 52

21. Thermochemical Data
Bond energies
C-H 99 kcal/mol
C-C 83
C C 143
C C 194

22. Thermochemical Data
Bond energies
Try to know some trends: