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  2. Sigma bond - Wikipedia

    en.wikipedia.org/wiki/Sigma_bond

    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. This rule is a special-case application of the Euler characteristic of the graph which represents the molecule. A molecule with no rings can be represented as a tree ...

  3. Carbon–carbon bond - Wikipedia

    en.wikipedia.org/wiki/Carbon–carbon_bond

    The carbon–carbon single bond is a sigma bond and is formed between one hybridized orbital from each of the carbon atoms. In ethane, the orbitals are sp 3-hybridized orbitals, but single bonds formed between carbon atoms with other hybridizations do occur (e.g. sp 2 to sp 2). In fact, the carbon atoms in the single bond need not be of the ...

  4. Sigmatropic reaction - Wikipedia

    en.wikipedia.org/wiki/Sigmatropic_reaction

    Hydrogens are omitted in the third example for clarity. A convenient means of determining the order of a given sigmatropic rearrangement is to number the atoms of the bond being broken as atom 1, and then count the atoms in each direction from the broken bond to the atoms that form the new σ-bond in the product, numbering consecutively.

  5. Inductive effect - Wikipedia

    en.wikipedia.org/wiki/Inductive_effect

    In Organic chemistry, the inductive effect in a molecule is a local change in the electron density due to electron-withdrawing or electron-donating groups elsewhere in the molecule, resulting in a permanent dipole in a bond. [1] It is present in a σ (sigma) bond, unlike the electromeric effect which is present in a π (pi) bond.

  6. Molecular orbital diagram - Wikipedia

    en.wikipedia.org/wiki/Molecular_orbital_diagram

    This MO is called the bonding orbital and its energy is lower than that of the original atomic orbitals. A bond involving molecular orbitals which are symmetric with respect to any rotation around the bond axis is called a sigma bond (σ-bond). If the phase cycles once while rotating round the axis, the bond is a pi bond (π-bond).

  7. Hyperconjugation - Wikipedia

    en.wikipedia.org/wiki/Hyperconjugation

    Bond length: Hyperconjugation is suggested as a key factor in shortening of sigma bondsbonds). For example, the single C–C bonds in 1,3-butadiene and propyne are approximately 1.46 Å in length, much less than the value of around 1.54 Å found in saturated hydrocarbons. For butadiene, this can be explained as normal conjugation of the ...

  8. 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.

  9. Sigma complex - Wikipedia

    en.wikipedia.org/wiki/Sigma_complex

    Transition metal alkane complexes (e.g., a methane complex) that bind solely through the C–H bond are also known but structurally characterized examples are rare, as C–H σ-bonds are generally poor electron donors, and, in many cases, the weakened C–H bond cleaves completely (C–H oxidative addition) to form a complex of type M(R)(H). [1]