Why Are Quadruple Bonds Not Possible?

If we go on to the valence-bond model, in which bonds result from the overlap of atomic orbitals

atomic orbitals
History. The term "orbital" was coined by Robert Mulliken in 1932 as an abbreviation for one-electron orbital wave function.
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, we see a better explanation: carbon cannot form a quadruple bond because it doesn't have enough atomic orbitals pointing in the right directions.

Are quadruple bonds possible?

Quadruple bonds do indeed exist, however one typically required d-orbitals in order for them to form. Diatomic carbon / dicarbon (C2) actually has a double bond. Although it has enough electrons to form a quadruple bond, the molecular orbitals don't work out. We have a net bond order of 2.

Why is a quadruple bond not possible between two carbon atoms?

Basically, the orbitals that allow for single, double, and triple bonds between carbons to not have to bend very much, but the last orbital which would allow for a quadruple bond would have to been too far, so it makes it impossible for carbon to form a quadruple bond with itself.

Sarah Jenkins

Sarah Jenkins

Senior Technology Editor & AI Specialist

Sarah Jenkins is a veteran tech journalist with over 12 years of experience covering artificial intelligence, mobile innovations, and digital ethics. Her insights have appeared in leading technology publications worldwide.