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  2. Sigma bond - Wikipedia

    en.wikipedia.org/wiki/Sigma_bond

    Organic molecules are often cyclic compounds containing one or more rings, such as benzene, and are often made up of many sigma bonds along with pi bonds. According to the sigma bond rule, the number of sigma bonds in a molecule is equivalent to the number of atoms plus the number of rings minus one. N σ = N atoms + N rings − 1

  3. Sigma-pi and equivalent-orbital models - Wikipedia

    en.wikipedia.org/wiki/Sigma-pi_and_equivalent...

    Two different explanations for the nature of double and triple covalent bonds in organic molecules were proposed in the 1930s. Linus Pauling proposed that the double bond in ethylene results from two equivalent tetrahedral orbitals from each atom, [5] which later came to be called banana bonds or tau bonds. [6]

  4. Pi bond - Wikipedia

    en.wikipedia.org/wiki/Pi_bond

    Quadruple bonds are extremely rare and can be formed only between transition metal atoms, and consist of one sigma bond, two pi bonds and one delta bond. A pi bond is weaker than a sigma bond, but the combination of pi and sigma bond is stronger than either bond by itself. The enhanced strength of a multiple bond versus a single (sigma bond) is ...

  5. Valence bond theory - Wikipedia

    en.wikipedia.org/wiki/Valence_bond_theory

    Pi bonds occur when two orbitals overlap when they are parallel. [9] For example, a bond between two s-orbital electrons is a sigma bond, because two spheres are always coaxial. In terms of bond order, single bonds have one sigma bond, double bonds consist of one sigma bond and one pi bond, and triple bonds contain one sigma bond and two pi bonds.

  6. Localized molecular orbitals - Wikipedia

    en.wikipedia.org/wiki/Localized_molecular_orbitals

    In the water molecule for example, ab initio calculations show bonding character primarily in two molecular orbitals, each with electron density equally distributed among the two O-H bonds. The localized orbital corresponding to one O-H bond is the sum of these two delocalized orbitals, and the localized orbital for the other O-H bond is their ...

  7. Ligand field theory - Wikipedia

    en.wikipedia.org/wiki/Ligand_field_theory

    These are the orbitals that are non-bonding when only σ bonding takes place. Example of π backbonding with carbonyl (CO) ligands. One important π bonding in coordination complexes is metal-to-ligand π bonding, also called π backbonding. It occurs when the LUMOs (lowest unoccupied molecular orbitals) of the ligand are anti-bonding π ...

  8. Electrocyclic reaction - Wikipedia

    en.wikipedia.org/wiki/Electrocyclic_reaction

    In organic chemistry, an electrocyclic reaction is a type of pericyclic, rearrangement reaction where the net result is one pi bond being converted into one sigma bond or vice versa. [1] These reactions are usually categorized by the following criteria: Reactions can be either photochemical or thermal.

  9. Allenes - Wikipedia

    en.wikipedia.org/wiki/Allenes

    The central carbon atom of allenes forms two sigma bonds and two pi bonds. The central carbon atom is sp-hybridized, and the two terminal carbon atoms are sp 2-hybridized. The bond angle formed by the three carbon atoms is 180°, indicating linear geometry for the central carbon atom.