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  2. Resonance (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Resonance_(chemistry)

    Contributing structures of the carbonate ion. In chemistry, resonance, also called mesomerism, is a way of describing bonding in certain molecules or polyatomic ions by the combination of several contributing structures (or forms, [1] also variously known as resonance structures or canonical structures) into a resonance hybrid (or hybrid structure) in valence bond theory.

  3. Organic azide - Wikipedia

    en.wikipedia.org/wiki/Organic_azide

    The azide functional group can be shown by two resonance structures. An organic azide is an organic compound that contains an azide (– N 3) functional group. [1] Because of the hazards associated with their use, few azides are used commercially although they exhibit interesting reactivity for researchers.

  4. Azide - Wikipedia

    en.wikipedia.org/wiki/Azide

    In chemistry, azide (/ ˈ eɪ z aɪ d /, AY-zyd) is a linear, polyatomic anion with the formula N − 3 and structure − N=N + =N −.It is the conjugate base of hydrazoic acid HN 3. Organic azides are organic compounds with the formula RN 3, containing the azide functional group. [1]

  5. Lewis structure - Wikipedia

    en.wikipedia.org/wiki/Lewis_structure

    Expressing resonance when drawing Lewis structures may be done either by drawing each of the possible resonance forms and placing double-headed arrows between them or by using dashed lines to represent the partial bonds (although the latter is a good representation of the resonance hybrid which is not, formally speaking, a Lewis structure ...

  6. Natural resonance theory - Wikipedia

    en.wikipedia.org/wiki/Natural_Resonance_Theory

    [1] [3] Once NRT has generated a set of density operators, Γ α, for localized resonance structures, α, a least-squares variational functional is employed to quantify the resonance weights of each structure. [1] It does this by measuring the variational error, δ w, of the linear combination of resonance structures to the true density ...

  7. Clar's rule - Wikipedia

    en.wikipedia.org/wiki/Clar's_rule

    Such a resonance structure is called a Clar structure. In other words, a polycyclic aromatic hydrocarbon with a given number of π-sextets is more stable than its isomers with fewer π-sextets. [1] [2] In 1984, Glidewell and Lloyd provided an extension of Clar's rule to polycyclic aromatic hydrocarbons containing rings of any size. [3]

  8. Squaric acid - Wikipedia

    en.wikipedia.org/wiki/Squaric_acid

    Squaric acid, also called quadratic acid because its four carbon atoms approximately form a square, is a diprotic organic acid with the chemical formula C 4 O 2 (OH) 2. [4]The conjugate base of squaric acid is the hydrogensquarate anion HC 4 O − 4; and the conjugate base of the hydrogensquarate anion is the divalent squarate anion C 4 O 2− 4.

  9. Stereoelectronic effect - Wikipedia

    en.wikipedia.org/wiki/Stereoelectronic_effect

    For instance, in the 1 H NMR, 3 J 23 higher than 3 J 56. [16] The C2-C3 double bond also selectively undergoes Diels–Alder reaction with cyclopentadiene, despite the increased steric hindrance on that side of the molecule. [17] These data illustrate an increased contribution of resonance structure B over structure A.