E

Electron-Deficient Compounds

Incomplete octet: e.g., BF₃, AlCl₃, B₂H₆
Quick Reference
Formula / NotationIncomplete octet: e.g., BF₃, AlCl₃, B₂H₆
Also Known AsLewis acid; incomplete octet compound; electron-poor compound; BF₃-type compound; boron compounds

What is Electron-Deficient Compounds?

Electron-deficient compounds are molecules or ions that have fewer than the expected number of electrons for a complete octet around the central atom. They act as Lewis acids (electron pair acceptors) and form adducts with electron-donating species (Lewis bases). Classic examples are boron trifluoride (BF₃), aluminium chloride (AlCl₃), and diborane (B₂H₆).

Formula & Notation

Incomplete octet: e.g., BF₃, AlCl₃, B₂H₆

Other Names / Synonyms: Lewis acid; incomplete octet compound; electron-poor compound; BF₃-type compound; boron compounds

Properties & Characteristics

Central atom has incomplete octet (< 8 electrons); strong Lewis acids; form coordinate bonds with Lewis bases; examples: BF₃ (6 electrons on B), AlCl₃ (6 electrons on Al), B₂H₆ (bridging 3-centre-2-electron bonds); tend to dimerize (AlCl₃ → Al₂Cl₆)

Uses & Applications

Friedel-Crafts catalysts (AlCl₃, BF₃); Lewis acid catalysts in organic synthesis; hydroboration reactions (B₂H₆, borane); synthesis of organoboron compounds; polymerisation catalysts

Safety Information

Boron trifluoride is toxic and corrosive; aluminium chloride reacts violently with water producing HCl. Diborane is flammable, toxic, and spontaneously ignites in moist air. Handle with extreme caution in dry, inert conditions with appropriate PPE.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Electron-Deficient Compounds
Formula Incomplete octet: e.g., BF₃, AlCl₃, B₂H₆
Synonyms Lewis acid; incomplete octet compound; electron-poor compound; BF₃-type compound; boron compounds

Frequently Asked Questions

Electron-deficient compounds are molecules or ions that have fewer than the expected number of electrons for a complete octet around the central atom. They act as Lewis acids (electron pair acceptors) and form adducts with electron-donating species (Lewis bases). Classic examples are boron trifluoride (BF₃), aluminium chloride (AlCl₃), and diborane (B₂H₆).

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