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  2. 18-electron rule - Wikipedia

    en.wikipedia.org/wiki/18-electron_rule

    The 18-electron rule is a chemical rule of thumb used primarily for predicting and rationalizing formulas for stable transition metal complexes, especially organometallic compounds. [1] The rule is based on the fact that the valence orbitals in the electron configuration of transition metals consist of five ( n −1)d orbitals, one n s orbital ...

  3. Tolman's rule - Wikipedia

    en.wikipedia.org/wiki/Tolman's_rule

    Tolman's rule states that, in a certain chemical reaction, the steps involve exclusively intermediates of 18- and 16 electron configuration. The rule is an extension of the 18-electron rule . This rule was proposed by American chemist Chadwick A. Tolman . [ 1 ]

  4. Organometallic chemistry - Wikipedia

    en.wikipedia.org/wiki/Organometallic_chemistry

    The 18-electron rule is helpful in predicting the stabilities of organometallic complexes, for example metal carbonyls and metal hydrides. The 18e rule has two representative electron counting models, ionic and neutral (also known as covalent) ligand models, respectively. [7] The hapticity of a metal-ligand complex, can influence the electron ...

  5. Electron counting - Wikipedia

    en.wikipedia.org/wiki/Electron_counting

    Many rules in chemistry rely on electron-counting: Octet rule is used with Lewis structures for main group elements, especially the lighter ones such as carbon, nitrogen, and oxygen, 18-electron rule [2] in inorganic chemistry and organometallic chemistry of transition metals, Hückel's rule for the π-electrons of aromatic compounds,

  6. Chemical reaction - Wikipedia

    en.wikipedia.org/wiki/Chemical_reaction

    The electron pair from the nucleophile attacks the substrate forming a new bond, while the leaving group departs with an electron pair. The nucleophile may be electrically neutral or negatively charged, whereas the substrate is typically neutral or positively charged. Examples of nucleophiles are hydroxide ion, alkoxides, amines and halides.

  7. Octet rule - Wikipedia

    en.wikipedia.org/wiki/Octet_rule

    The bonding in carbon dioxide (CO 2): all atoms are surrounded by 8 electrons, fulfilling the octet rule.. The octet rule is a chemical rule of thumb that reflects the theory that main-group elements tend to bond in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas.

  8. 18 (number) - Wikipedia

    en.wikipedia.org/wiki/18_(number)

    Group 18 of the periodic table is called the noble gases. The 18-electron rule is a rule of thumb in transition metal chemistry for characterising and predicting the stability of metal complexes. 18 is the number of ways to represent the word 'Floccinaucinihilipilification' using chemical element symbols.

  9. Transition metal hydride - Wikipedia

    en.wikipedia.org/wiki/Transition_metal_hydride

    A celebrated example is K 2 ReH 9, a salt containing two K + ions and the ReH 9 2− anion. Other homoleptic metal hydrides include the anions in Mg 2 FeH 6 and Mg 2 NiH 4. Some of these anionic polyhydrides satisfy the 18-electron rule, many do not.