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  2. Molecular electronic transition - Wikipedia

    en.wikipedia.org/.../Molecular_electronic_transition

    For example, the absorption spectrum for ethane shows a σ → σ* transition at 135 nm and that of water a n → σ* transition at 167 nm with an extinction coefficient of 7,000. Benzene has three aromatic π → π* transitions; two E-bands at 180 and 200 nm and one B-band at 255 nm with extinction coefficients respectively 60,000, 8,000 and 215.

  3. Hückel method - Wikipedia

    en.wikipedia.org/wiki/Hückel_method

    The method predicts how many energy levels exist for a given molecule, which levels are degenerate and it expresses the molecular orbital energies in terms of two parameters, called α, the energy of an electron in a 2p orbital, and β, the interaction energy between two 2p orbitals (the extent to which an electron is stabilized by allowing it ...

  4. Ligand field theory - Wikipedia

    en.wikipedia.org/wiki/Ligand_field_theory

    The metal also has six valence orbitals that span these irreducible representations - the s orbital is labeled a 1g, a set of three p-orbitals is labeled t 1u, and the d z 2 and d x 2 −y 2 orbitals are labeled e g. The six σ-bonding molecular orbitals result from the combinations of ligand SALCs with metal orbitals of the same symmetry.

  5. Extended Hückel method - Wikipedia

    en.wikipedia.org/wiki/Extended_Hückel_method

    It is based on the Hückel method but, while the original Hückel method only considers pi orbitals, the extended method also includes the sigma orbitals. The extended Hückel method can be used for determining the molecular orbitals , but it is not very successful in determining the structural geometry of an organic molecule .

  6. Antibonding molecular orbital - Wikipedia

    en.wikipedia.org/wiki/Antibonding_molecular_orbital

    There are two bonding pi orbitals which are occupied in the ground state: π 1 is bonding between all carbons, while π 2 is bonding between C 1 and C 2 and between C 3 and C 4, and antibonding between C 2 and C 3. There are also antibonding pi orbitals with two and three antibonding interactions as shown in the diagram; these are vacant in the ...

  7. Pi bond - Wikipedia

    en.wikipedia.org/wiki/Pi_bond

    Two p-orbitals forming a π-bond. Pi bonds are usually weaker than sigma bonds.The C-C double bond, composed of one sigma and one pi bond, [1] has a bond energy less than twice that of a C-C single bond, indicating that the stability added by the pi bond is less than the stability of a sigma bond.

  8. Molecular orbital - Wikipedia

    en.wikipedia.org/wiki/Molecular_orbital

    This function can be used to calculate chemical and physical properties such as the probability of finding an electron in any specific region. The terms atomic orbital and molecular orbital [a] were introduced by Robert S. Mulliken in 1932 to mean one-electron orbital wave functions. [2]

  9. Pi backbonding - Wikipedia

    en.wikipedia.org/wiki/Pi_backbonding

    In chemistry, pi backbonding or π backbonding is a π-bonding interaction between a filled (or half filled) orbital of a transition metal atom and a vacant orbital on an adjacent ion or molecule. [ 1 ] [ 2 ] In this type of interaction, electrons from the metal are used to bond to the ligand , which dissipates excess negative charge and ...