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Many aromatic and antiaromatic compounds (benzene and cyclobutadiene) are too small to have protons inside of the ring, where shielding and deshielding effects can be more diagnostically useful in determining if a compound is aromatic, antiaromatic, or nonaromatic. Nucleus Independent Chemical Shift (NICS) analysis is a method of computing the ...
The compound is the prototypical antiaromatic hydrocarbon with 4 pi electrons (or π electrons). It is the smallest [n]-annulene ([4]-annulene).Its rectangular structure is the result of a pseudo [3] - (or second order) Jahn–Teller effect, which distorts the molecule and lowers its symmetry, converting the triplet to a singlet ground state. [4]
In contrast, the corresponding [12]-and [16]annulenes, which are weakly antiaromatic or nonaromatic, have downfield shifted interior hydrogens. However, unlike the undoubtedly aromatic [18]annulene , [14]annulene does not bear the hallmark aromatic property of chemical stability, and it quickly decomposes when exposed to light and air.
Aliphatic compounds can be saturated, joined by single bonds , or unsaturated, with double bonds or triple bonds . If other elements ( heteroatoms ) are bound to the carbon chain , the most common being oxygen , nitrogen , sulfur , and chlorine , it is no longer a hydrocarbon, and therefore no longer an aliphatic compound.
1,4-Dioxin (also referred as dioxin or p-dioxin) is a heterocyclic, organic, non-aromatic [2] compound with the chemical formula C 4 H 4 O 2.There is an isomeric form of 1,4-dioxin, 1,2-dioxin (or o-dioxin). 1,2-Dioxin is very unstable due to its peroxide-like characteristics.
Aromaticity can be induced in compounds having a [10]annulene-type core if planarity is forcibly imposed by other substituents. Two methods to do so are known. One method is to formally replace two hydrogen atoms by a methylene bridge ( −CH 2 − ); this gives the planar bicyclic 1,6-methano[10]annulene ( 5 ).
Natural bond orbital (NBO) analysis of C 4 H 4 BH has been performed in order to understand the bonding of borole in the familiar Lewis picture. [5] According to the computational results, the occupancy of the two C−C π orbitals is about 1.9, with a tiny amount of electronic charge (an occupancy of 0.13) delocalised on the out-of-plane boron p orbital, illustrated below.
A cyclic compound or ring compound is a compound in which at least some its atoms are connected to form a ring. [1] Rings vary in size from three to many tens or even hundreds of atoms. Examples of ring compounds readily include cases where: all the atoms are carbon (i.e., are carbocycles),