Stereoisomerism
Isomers having the same connectivity but differing in the spatial arrangement of atoms or groups around the central metal ion.
What is Stereoisomerism?
Isomers that have the same molecular formula and connectivity but differ in the three-dimensional arrangement of their atoms or groups in space.
Key points
- Define stereoisomerism in coordination compounds.
- Differentiate between geometrical and optical isomerism.
- Identify complexes that exhibit geometrical isomerism.
- Determine if a complex can exhibit optical isomerism (chirality).
Common exam trap
Confusing stereoisomers with structural isomers (which have different connectivity).
Definitions
- Term
Stereoisomers
- Meaning
Isomers that have the same molecular formula and connectivity but differ in the three-dimensional arrangement of their atoms or groups in space.
- Term
Geometrical Isomerism
- Meaning
A type of stereoisomerism in which isomers have different spatial arrangements of ligands around the central metal atom, particularly in cis (adjacent) and trans (opposite) positions.
- Term
Optical Isomerism
- Meaning
A type of stereoisomerism in which isomers are chiral and exist as non-superimposable mirror images (enantiomers), rotating plane-polarized light in opposite directions.
- Term
Chirality
- Meaning
The property of a molecule or ion of being non-superimposable on its mirror image.
- Term
Enantiomers
- Meaning
A pair of stereoisomers that are non-superimposable mirror images of each other.
Learning objectives
Define stereoisomerism in coordination compounds.
Differentiate between geometrical and optical isomerism.
Identify complexes that exhibit geometrical isomerism.
Determine if a complex can exhibit optical isomerism (chirality).
Prerequisites
Coordination Compounds: Definition, Central Metal Ion, Ligands.
Types of Ligands: Monodentate, Bidentate, Polydentate.
Coordination Number and Geometry (e.g., tetrahedral, square planar, octahedral).
Valence Bond Theory (VBT) and Crystal Field Theory (CFT) basics.
Common mistakes
Confusing stereoisomers with structural isomers (which have different connectivity).
Incorrectly identifying the possibility of geometrical isomerism based solely on the number of different ligands.
Failing to recognize chiral centers or planes of symmetry in complexes, leading to misidentification of optical isomers.
Keywords
Stereoisomerism
Coordination Compounds
Geometrical Isomerism
Optical Isomerism
Chirality
Enantiomers
Cis
Trans
Ligands
Central Metal Ion
Practice preview
Consider the complex [Cr(ox)2(en)]-. Which statement about its isomerism is correct?…
hard
Geometrical isomerism in coordination compounds is primarily observed in complexes with which coordination numbers?…
easy
The cis isomer of [Co(en)2Cl2]+ exhibits optical isomerism, while its trans isomer does not. This is because:…
medium