1. Chapter 2 Stereo chemistry ISOMERISM 2. 1
Chapter 2 Stereo chemistry ISOMERISM Review of common stereo-chemistries Stereochemistry the branch of chemistry concerned with the three-dimensional arrangement of atoms and molecules and the effect of this on chemical reactions.

2. Louis Pasteur could rightly be described as the first stereochemist, having observed in 1849 that salts of tartaric acid collected from wine production vessels could rotate plane polarized light, but that salts from other sources did not. This property, the only physical property in which the two types of tartrate salts differed, is due to optical isomerism. In 1874, Jacobus Henricus van 't Hoff and Joseph Le Bel explained optical activity in terms of the tetrahedral arrangement of the atoms bound to carbon.
History

3. Same formula, different arrangement

4. Structural (constitutional) and stereo isomers

7. 2.2. Structural Isomerism 1. Coordination isomerism:
Composition of the complex ion varies.
[Cr(NH3)5SO4]Br
and [Cr(NH3)5Br]SO4

8. Structural Isomerism 2. Ligand (linkage) isomerism:
Same complex ion structure but point of attachment of at least one of the ligands differs.
[Co(NH3)5(NO2)]Cl2
and [Co(NH3)5(ONO)]Cl2

11. Linkage Isomers [Co(NH3)5(NO2)]Cl2 [Co(NH3)5(ONO)]Cl2
Pentaamminenitrocobalt(III)
chloride
[Co(NH3)5(ONO)]Cl2
Pentaamminenitritocobalt(III)
chloride

12. 3. Ionization isomerism IONIZATION ISOMERISM
Certain isomeric pairs occur that differ only in that two ionic groups exchange positions within (and without) the primary coordination sphere.
These are called ionization isomers and are exemplified by the two compounds, pentaamminebromocobalt sulfate, [CoBr(NH3)5]SO4, and pentaamminesulfatocobalt bromide, [Co(SO4)(NH3)5]Br. In the former the bromide ion is coordinated to the cobalt(3+) ion, and the sulfate ion is outside the coordination sphere; in the latter the sulfate ion occurs within the coordination sphere, and the bromide ion is outside it.

14. 4.

16. 2.3.Geometric isomerism (cis-trans):
Atoms or groups arranged differently spatially relative to metal ion
Pt(NH3)2Cl2

18. Trans - diastereoisomers
Cis-enantiomers

19. Stereoisomerism 2 1.Optical isomerism:
Have opposite effects on plane-polarized light
(no superimposable mirror images)