Co-ordinate Bond

Coordinate Bond is a special type of covalent bond in which both electrons or an electron pair that is shared between two atoms come from the same atom. Coordinate bonds are also called Dative Bonds or Dipolar Bonds. Coordinate bonds are commonly found in coordination compounds.

In this article, we will look into what a coordinate bond is, its characteristics, examples, and others in detail.

What is a Coordinate Bond?

Coordinate bond, also known as a dative bond, dipolar bond, or coordinate covalent bond, is a type of two-center, two-electron covalent bond in which the two electrons derive from the same atom. This type of bonding is central to Lewis acid–base theory and is commonly found in coordination compounds.

Coordinate covalent bonding occurs when an atom donates a lone pair of electrons to another atom, forming a shared electron pair.

Learn, Chemical Bonds

Compounds With Coordinate Bonds

Various compounds that are formed using Coordinate Bonds are,

• Carbon Monoide
• Ammonia Boron Trifluoride
• Ammonium Ion
• Hydronium Ion, etc.

Characteristics of Coordinate Covalent Bond

Some chracterstics of Coordinate Covalent Bond are,

• Electron Pair Sharing: A coordinate bond is a type of covalent bond in which both electrons in the bond come from the same atom.

• Donor and Acceptor: In coordinate bonding, one atom acts as the donor, sharing a pair of electrons, and the other atom acts as the acceptor, receiving the shared electron pair to attain a stable electronic configuration.

• Formation: Coordinate covalent bonds are usually formed in reactions that involve two non-metals, such as a hydrogen atom, or during bond formation between metal ions and ligands.

• Polarity: Coordinate bonds are always polar because they are formed between two unlike atoms.

• Representation: In simple diagrams, a coordinate bond is shown by an arrow pointing from the atom, donating the lone pair to the atom accepting it.

• Strength: Coordinate covalent bonds are usually strong, similar to other interatomic bonds.

Types of Coordinate Bonds

Depending on the specific context and the atoms involved, these bonds can be considered either weak or strong.

• Weak Coordinate Covalent Bonds: In some cases, coordinate covalent bonds can be weaker than other covalent bonds due to the nature of the atoms involved or the bonding arrangement. For example, coordinate covalent bonds formed between non-metals or between a central electrophile and a ligand can be weaker than ionic bonds.

• Strong Coordinate Covalent Bonds: In other cases, coordinate covalent bonds can be strong and have properties similar to other covalent bonds. For instance, coordinate covalent bonds formed between transition metals or between two like atoms can be strong.

Coordinate Bond Examples

Here are a few examples of coordinate covalent bonds

Coordinate Bond in Ammonium Ion (NH₄⁺)

Formation of ammonium ions involves a coordinate covalent bond. In this case, the nitrogen atom in ammonia (NH₃) donates its lone pair of electrons to the hydrogen ion (H⁺). The nitrogen atom is the donor, and the hydrogen ion is the acceptor. The coordinate covalent bond is represented by an arrow pointing from the nitrogen atom to the hydrogen ion.

👁 Ammonium-Ion

Coordinate Bond in Aluminum Chloride (AlCl₃)

Aluminum chloride is formed through a coordinate covalent bond between two chlorine atoms. In this case, both chlorine atoms have lone pairs of electrons, and one of these lone pairs is donated to the aluminum atom to complete its outer shell. This results in forming a dimer, which is electron-deficient and requires two electrons to complete its outer shell.

👁 Aluminium-Chloride

Coordinate Bond in Hydronium Ion

Hydronium Ion is formed when oxygen atom in water denotes an electron pair of electrons to the vacant orbital of H⁺ ion. The structure for the same is shown in the image added below,

👁 Hydronium-Ion

Coordinate Bond in Ammonia Boron Trifluoride

Ammonia Boron Trifluoride is formed when nitrogen atom in Ammonia donates one pair of electrons to the vacant orbital of the Boron atom in the Boron Trifluoride. The structure for the same is shown in the image added below,

👁 Ammonium-Boron-Triflouride

Coordinate Bond in Transition Metal Complexes

Coordinate covalent bonding is common in transition metal complexes, where a central electrophile (usually a transition metal ion) bonds with one or more nucleophiles (ligands). For example, in the complex [VO]SO₄, Vanadium (VO) acts as the central electrophile, and sulfate (SO₄) serves as the ligand. The sulfate ligand has a lone pair of electrons to donate to the vanadium ion, forming a coordinate covalent bond.

Properties of Coordinate Bond

The properties of a coordinate bond include:

• Directionality: A coordinate bond is a directional bond because the sharing of electrons takes place in a specific direction.

• Isomerism: Some coordinate compounds exhibit isomerism, which is the existence of two or more compounds with the same molecular formula but different structural formulas.

• Melting and Boiling Points: Coordinate compounds generally have lower melting and boiling points than ionic compounds.

• Strength: Since they involve the sharing of electron pairs, they are stronger than hydrogen bonds but relatively weaker than ionic bonds.

Coordinate and Covalent Bond

Coordinate bonds and covalent bonds are two types of chemical bonds that hold atoms together in molecules.

• Covalent Bond: A covalent bond is a type of chemical bond formed when two atoms share electrons in order to achieve a more stable electron configuration.
• Coordinate Bond (Dative Bond): A coordinate bond, also known as a dative bond, is a type of covalent bond in which both of the shared electrons come from one of the atoms involved in the bond.

Coordinate Vs Covalent Bond

Differences Between Coordinate Bond and Covalent Bond is added in the table below,

Features	Coordinate bond	Covalent bond
Electron Sharing	In a coordinate bond, one atom donates a lone pair of electrons to another atom.	In a covalent bond, both atoms share their electrons.
Electron Donation	Only one atom donates a pair of electrons for bond formation	Two atoms donate an equal number of electrons for bond formation.
Presence of Unpaired Electrons	Formed when at least one lone electron pair is present in one of the two atoms	Formation of a covalent bond requires both atoms to have unpaired electrons, as each atom supplies one electron to the bond
Polarity	Always polar because they are formed between two unlike atoms.	Can be either polar or nonpolar.

Some Compounds and their Coordinate Bonds

Coordinate Bond in SO₃

There are no coordinate bond in SO₃

Coordinate Bond in H₂SO₄

There are no coordinate bond in H₂SO₄

Coordinate Bond in HNO₃

There is only one coordinate bond in HNO₃

Read More,

• Types of Bonding
• Ionic Bond
• Covalent Bond

Coordinate Bond JEE Questions

Q1. A simple example of a coordinate covalent bond is exhibited by

1. C₂H₂
2. H₂SO₄
3. H₂O
4. HCl

Option (2) H₂SO₄ Is Correct

Q2. The bond that exists between NH₃ and BF₃ is called

1. Electrovalent
2. Covalent
3. Coordinate
4. Hydrogen

Option (3)Coordinate Is Correct

Q3. Coordinate covalent compounds are formed by

1. Transfer of electrons
2. Sharing of electrons
3. Donation of electrons
4. None of these process

Option (3) Donation of electrons Is Correct

Q4. In the coordinate valency

1. Electrons are equally shared by the atoms
2. Electrons of one atom are shared with two atoms
3. Hydrogen bond is formed
4. None of the above

Option (2) Electrons of one atom are shared with two atoms Is Correct

Q5. Which has a coordinate bond

1. SO₂⁻³
2. CH₄
3. CO₂
4. NH₃

Option(A)SO₂⁻³ is correct

Structure of SO₂⁻³

⁻O−S−O⁻

↓

O