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  2. Hückel method - Wikipedia

    en.wikipedia.org/wiki/Hückel_method

    The Hückel method or Hückel molecular orbital theory, proposed by Erich Hückel in 1930, is a simple method for calculating molecular orbitals as linear combinations of atomic orbitals. The theory predicts the molecular orbitals for π-electrons in π-delocalized molecules , such as ethylene , benzene , butadiene , and pyridine .

  3. Allyl group - Wikipedia

    en.wikipedia.org/wiki/Allyl_group

    Resonance structure of the allyl anion. The cation is identical, but carries an opposite-sign charge. [7] In terms of MO theory, the MO diagram has three molecular orbitals: the first one bonding, the second one non-bonding, and the higher energy orbital is antibonding. [2] MO diagram for allyl π orbitals.

  4. Molecular orbital diagram - Wikipedia

    en.wikipedia.org/wiki/Molecular_orbital_diagram

    Molecular orbital diagram of NO. Nitric oxide is a heteronuclear molecule that exhibits mixing. The construction of its MO diagram is the same as for the homonuclear molecules. It has a bond order of 2.5 and is a paramagnetic molecule. The energy differences of the 2s orbitals are different enough that each produces its own non-bonding σ orbitals.

  5. Bond order - Wikipedia

    en.wikipedia.org/wiki/Bond_order

    In chemistry, bond order is a formal measure of the multiplicity of a covalent bond between two atoms. As introduced by Gerhard Herzberg, [1] building off of work by R. S. Mulliken and Friedrich Hund, bond order is defined as the difference between the numbers of electron pairs in bonding and antibonding molecular orbitals.

  6. Molecular orbital theory - Wikipedia

    en.wikipedia.org/wiki/Molecular_orbital_theory

    Molecular orbital diagram of He 2. Bond order is the number of chemical bonds between a pair of atoms. The bond order of a molecule can be calculated by subtracting the number of electrons in anti-bonding orbitals from the number of bonding orbitals, and the resulting number is then divided by two. A molecule is expected to be stable if it has ...

  7. Localized molecular orbitals - Wikipedia

    en.wikipedia.org/wiki/Localized_molecular_orbitals

    Localized molecular orbitals are molecular orbitals which are concentrated in a limited spatial region of a molecule, such as a specific bond or lone pair on a specific atom. They can be used to relate molecular orbital calculations to simple bonding theories, and also to speed up post-Hartree–Fock electronic structure calculations by taking ...

  8. Transition-metal allyl complex - Wikipedia

    en.wikipedia.org/wiki/Transition-metal_allyl_complex

    The allyl ligand is commonly in organometallic chemistry.Usually, allyl ligands bind to metals via all three carbon atoms, the η 3-binding mode.The η 3-allyl group is classified as an LX-type ligand in the Green LXZ ligand classification scheme, serving as a 3e – donor using neutral electron counting and 4e – donor using ionic electron counting.

  9. Carbenium ion - Wikipedia

    en.wikipedia.org/wiki/Carbenium_ion

    The tert-butyl cation is a relatively stable carbenium ion. [1] A carbenium ion is a positive ion with the structure RR′R″C +, that is, a chemical species with carbon atom having three covalent bonds, and it bears a +1 formal charge. Carbenium ions are a major subset of carbocations, which