Aryl-substituted derivatives of trimethylenemethane dianion: a dynamic NMR study

Shenhar, Roy; Rabinovitz, Mordecai

doi:10.1039/a704020b

Cited by 3 publications

(1 citation statement)

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“…For about 25 years are being studied the noncyclic, "Y-shaped", aromatic species. [62][63][64][65][66][67][68][69][70][71] TOPAZ identifies as "Y-shaped" aromatic molecules, for instance, the urea (A = 255), thiourea (A = 248) and guanidine (A = 479). In these molecules, the algorithm we have proposed here identifies a unique aromatic zone including all the heavy atoms.…”

Section: Aromatic Zonesmentioning

confidence: 99%

Aromatic molecular zones and fragments

Tarko¹

2008

Arkivoc

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An edge on the weighted molecular graph is aromatic if the bond order B value is within [α, β] range. A certain "non-conjugated topological path" includes minimum two adjacent "single" edges (B < α). The topological paths that are not "non-conjugated" are "conjugated topological paths". An aromatic zone is a collection of contiguous aromatic edges. An aromatic fragment is a topological path within aromatic zone. The proposed aromaticity formula measures the aromaticity of zones and any "conjugated paths" via two variables that gauge deviations of bond orders from a reference value and of atom hybridization from sp 2 character. The aromaticity of "non-conjugated paths" is, conventionally, null. The analysis of organic/inorganic molecules, ions and radicals, including those having cyclic, non-cyclic, planar and non-planar geometries, uses a unique set of parameters. The larger the deviation from Hückel rules, the smaller (even negative) is the computed aromaticity value. The paper presents a few non-aromatic Hückel and aromatic non-Hückel structures. After geometry optimization by PM6 method, one can compute the value of some aromaticity molecular descriptors, useful in QSPR computations. The paper includes a list of some descriptors that are measurements of the aromaticity of zones and aromatic "conjugated topological paths".

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