multiple bonds

[Bethel Tesfamicael]

Is it possible to have a quadruple bond something like [C (- 4X) C ]and if so how many sigma bonds or pi bonds would that consist of?

[505989311]

No, a quadruple bond like [C----C] is not possible. Multipule bonds between oxygens are limited to a triple bonds due to the orbital hybridization of carbon atoms. A triple bond consists of one sigma bond and two pi bonds.

[Levy Shaked]

Agreed; a quadruple bond is geometrically impossible, as it would—hypothetically, as double bonds have sp2 hybridization and triple bonds have sp hybridization—result in just 's' hybridization and would require all three p orbitals free for pi bonding. This would mean that both the s orbital and a p orbital in each of the bonding atoms would occupy the space in between them, which (as orbitals cannot occupy the same position in space) is impossible.