IB Chemistry Topic R3.4.8 Ligands and Coordination Bond Revision Notes (HL)

IB Chemistry Topic R3.4.8 Ligands and Coordination Bond Revision Notes (HL) | RevisionDojo

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What Are Coordination Bonds?

Definition

Coordination bond

A coordination bond (also known as a dative covalent bond) forms when both electrons in the shared pair come from the same atom.

In the context of complex ions, this occurs when a ligand donates a lone pair of electrons to a transition metal cation.
Ligands can be ranked by field strength, from weak-field to strong-field: $$
\mathrm{I}^{-}<\mathrm{Br}^{-}<\mathrm{S}^{2-}<\mathrm{Cl}^{-}<\mathrm{F}^{-}<\mathrm{OH}^{-}<\mathrm{H}_2 \mathrm{O}<\mathrm{SCN}^{-}<\mathrm{NH}_3<\mathrm{CN}^{-} \approx \mathrm{CO}
$$ and a stronger field gives a bigger split and a different colour.

Definition

Ligand

A molecule or ion that donates a lone pair of electrons to a central metal ion to form a coordination bond.

Example

Common ligands include water ($H_2O$), ammonia ($NH_3$), and chloride ions ($Cl^-$).

Other important definitions:

Transition Metal Cation: A positively charged ion of a transition metal, which has vacant orbitals capable of accepting electron pairs from ligands.
Complex Ion: A charged species consisting of a central metal ion surrounded by ligands bonded through coordination bonds.

Tip

Ligands must have at least one lone pair of electrons to form a coordination bond with the metal ion.

How Are Coordination Bonds Formed?

Coordination bonds are formed when ligands donate their lone pairs of electrons to the empty orbitals of a transition metal cation.
This process can be broken down into the following steps:
1. Electron Pair Donation: The ligand, which has a lone pair of electrons, approaches the transition metal cation.

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What Are Coordination Bonds?

Definition

Coordination bond

A coordination bond (also known as a dative covalent bond) forms when both electrons in the shared pair come from the same atom.

In the context of complex ions, this occurs when a ligand donates a lone pair of electrons to a transition metal cation.
Ligands can be ranked by field strength, from weak-field to strong-field: $$
\mathrm{I}^{-}<\mathrm{Br}^{-}<\mathrm{S}^{2-}<\mathrm{Cl}^{-}<\mathrm{F}^{-}<\mathrm{OH}^{-}<\mathrm{H}_2 \mathrm{O}<\mathrm{SCN}^{-}<\mathrm{NH}_3<\mathrm{CN}^{-} \approx \mathrm{CO}
$$ and a stronger field gives a bigger split and a different colour.

Definition

Ligand

A molecule or ion that donates a lone pair of electrons to a central metal ion to form a coordination bond.

Example

Common ligands include water ($H_2O$), ammonia ($NH_3$), and chloride ions ($Cl^-$).

Other important definitions:

Transition Metal Cation: A positively charged ion of a transition metal, which has vacant orbitals capable of accepting electron pairs from ligands.
Complex Ion: A charged species consisting of a central metal ion surrounded by ligands bonded through coordination bonds.

Tip

Ligands must have at least one lone pair of electrons to form a coordination bond with the metal ion.

How Are Coordination Bonds Formed?

Coordination bonds are formed when ligands donate their lone pairs of electrons to the empty orbitals of a transition metal cation.
This process can be broken down into the following steps:
1. Electron Pair Donation: The ligand, which has a lone pair of electrons, approaches the transition metal cation.

Definition

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Structure 1. Models of the particulate nature of matter5 subtopics

Structure 2. Models of bonding and structure4 subtopics

Structure 3. Classification of matter2 subtopics

Reactivity 1. What drives chemical reactions?4 subtopics

Reactivity 2. How much, how fast and how far?3 subtopics

Reactivity 3. What are the mechanisms of chemical change?4 subtopics

IB Chemistry R3.4.8 Ligands and Coordination Bond Notes

Structure 1. Models of the particulate nature of matter5 subtopics

Structure 2. Models of bonding and structure4 subtopics

Structure 3. Classification of matter2 subtopics

Reactivity 1. What drives chemical reactions?4 subtopics

Reactivity 2. How much, how fast and how far?3 subtopics

Reactivity 3. What are the mechanisms of chemical change?4 subtopics

What Are Coordination Bonds?

How Are Coordination Bonds Formed?

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What Are Coordination Bonds?

How Are Coordination Bonds Formed?

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