Chemical Bonding – Coordinate Bond (Dative Bond)

A coordinate bond, also known as a dative covalent bond, is a type of covalent bond in which both electrons in the shared pair come from the same atom. It is commonly observed when a lone pair from one atom is donated to an electron-deficient species.

Formation

• Donor: Atom with a lone pair of electrons (N, O, etc.).
• Acceptor: Electron-deficient atom or ion (e.g., H⁺, metal cations).

Representation: Denoted by an arrow (→) from donor to acceptor atom.

Examples

• Ammonium ion (NH₄⁺): NH3 + H+ → NH4+
• Hydronium ion (H₃O⁺): Water donates a lone pair to H⁺.
• Carbon monoxide (CO): O donates lone pair to C forming a triple bond (one coordinate).
• Complex ions: [Cu(NH₃)₄]²⁺, where NH₃ donates lone pairs.

Properties

• Behaves like a covalent bond after formation.
• Common in coordination compounds.
• Observed in Lewis acid-base reactions.
• Important in transition metal chemistry and polyatomic ions.

Quiz: Test Your Knowledge

1. What makes a coordinate bond different from a covalent bond?
2. Which ion is formed when NH₃ donates a lone pair to H⁺?
3. What symbol represents a coordinate bond?
4. Give two examples of coordinate bonded compounds.
5. Explain bonding in H₃O⁺.

Answers

1. Both electrons in a coordinate bonds come from the donor atom.
2. Ammonium ion (NH₄⁺).
3. Arrow (→) from donor to acceptor.
4. NH₄⁺, CO, H₃O⁺, [Cu(NH₃)₄]²⁺.
5. Oxygen donates a lone pair to H⁺ → H₃O⁺.

FAQs

Q1: Is a coordinate bonds weaker than a covalent bond?
Ans: No, once formed, a coordinate bond is indistinguishable from a covalent bond in strength.

Q2: How do you identify a coordinate bond?
Ans: Look for lone pairs donated from one atom to an electron-deficient atom (represented by →).

Q3: Where are coordinate bonds commonly found?
Ans: In complex ions, polyatomic ions, and Lewis acid-base reactions.

Read also: Bond Parameters | Inorganic Chemistry