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In the first place, Clar's rule is formulated only for species with hexagonal rings, [12] and thus it cannot be applied to species having rings different from the benzene moiety, even though an extension of the rule to molecules with rings of any dimension has been provided by Glidewell and Lloyd. [12]
The symmetrical molecule [3.3]orthocyclophane, also known as janusene, is a cyclophane that contains 4 benzene rings in a cleft-shaped arrangement. First synthesized in 1967 by Stanley J. Cristol through the cycloaddition of anthracene and dibenzobarrelene, [ 22 ] the molecule has been used to study stacking and interactions between cations and ...
Hexafluorobenzene stands somewhat aside in the perhalogenbenzenes. If a perhalogenated benzene ring were to remain planar, then geometric constraints would force adjacent halogens closer than their associated nonbonding radius. Consequently the benzene ring buckles, reducing p-orbital overlap and aromaticity to avoid the steric clash ...
In alkanes, optimum overlap of atomic orbitals is achieved at 109.5°. The most common cyclic compounds have five or six carbons in their ring. [6] Adolf von Baeyer received a Nobel Prize in 1905 for the discovery of the Baeyer strain theory, which was an explanation of the relative stabilities of cyclic molecules in 1885.
The chemical shift for the protons outside its ring is 5.91 ppm and that for the protons inside the ring is 7.86 ppm, compared to the normal range of 4.5-6.5 ppm for nonaromatic alkenes. This effect is of a smaller magnitude than the corresponding shifts in aromatic compounds.
Aromaticity also occurs in compounds that are not carbon-based at all. Inorganic 6-membered-ring compounds analogous to benzene have been synthesized. Hexasilabenzene (Si 6 H 6) and borazine (B 3 N 3 H 6) are structurally analogous to benzene, with the carbon atoms replaced by another element or elements. In borazine, the boron and nitrogen ...
Benzene, the most widely recognized aromatic compound with six delocalized π-electrons (4n + 2, for n = 1). In organic chemistry , Hückel's rule predicts that a planar ring molecule will have aromatic properties if it has 4 n + 2 π-electrons , where n is a non-negative integer .
The stable conformation of this molecule has the phenyl rings rotated out of the plane of the central benzene ring. The molecule adopts a propeller-like conformation in which the phenyl rings are rotated about 65°, [ 4 ] while in the gas phase, they are perpendicular with some slight oscillations.