Bonding In Coordination Compounds
Chapter Name : Coordination Compounds |
Sub Topic Code : 102_12_09_05_06 |
Topic Name : Bonding In Coordination Compounds |
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Sub Topic Name : Limitations Of Crystal Field Theory |
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Introduction
Coordination complex or metal complex, consists of an atom or ion (usually metallic), and a surrounding array of bound molecules or anions, that are in turn known as ligands or complexing agents.
Pre-Requisites:
Coordination Compounds
Activity:
Nickel tetracarbonyl.
Real Life Question:
What are Coordination Compounds?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Crystal field theory | Crystal field theory (CFT) is a model that describes the breaking of degeneracies of electronic orbital states, usually d or f orbitals, due to a static electric field produced by a surrounding charge distribution (anion neighbors). |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| Ethylenediaminetetraacetic acid | Ethylenediaminetetraacetic acid (EDTA) is used for estimation of Ca2+ and Mg2+ in hard water. |
Real life uses :
Study of organometals.
Places to visit :
Pharmacy.
Practical examples around us
| Examples | Explainations |
|---|---|
| Nickel tetracarbonyl | It is an intermediate in the Mond process for the purification of nickel and a reagent in organometallic chemistry. |
What you learn in Theory:
The most obvious limit of this theory is that it can't explain the color of substances with a full or empty d orbital. (Since it only considers d orbitals) an example of these substances is kmno4 in which the d orbital is empty. There is another kind of electron transfer called charge transfer (ct) which is more powerful than d-d transfer and is between metal and ligand. This type of electron transfer is not covered in crystal field theory and can only be explained using mot (molecular orbital theory).
What you learn in Practice:
In crystal field theory the metal ion is assumed to be free in gas form, the ligands are assumed to behave like point charges and it is assumed that the orbitals of the metal and the ligands do not interact.