Results 151 to 160 of about 1,373 (200)

On the Number of Benzenoid Hydrocarbons

Journal of Chemical Information and Computer Sciences, 2002
We present a new algorithm which allows a radical increase in the computer enumeration of benzenoids b(h) with h hexagons. We obtain b(h) up to h = 35. We prove that b(h) approximately const.kappa(h), prove the rigorous bounds 4.789 < or = kappa < or = 5.905, and estimate that kappa = 5.16193016(8).
Markus Vöge, Anthony J. Guttmann, Iwan Jensen   +2 more
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Embedding in Benzenoid Hydrocarbons

Journal of Chemical Information and Computer Sciences, 1996
Using the embedding scheme and a rule we proposed previously, in this work we discuss common eigenvalues and their degeneracies in benzenoid molecular graphs.
Jun Liu, Yuansheng Jiang
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Algebraic Kekulé Structures of Benzenoid Hydrocarbons

Journal of Chemical Information and Computer Sciences, 2004
An algebraic Kekulé structure of a benzenoid hydrocarbon is obtained from an ordinary Kekulé structure by inscribing into each hexagon the number of pi-electrons which (according to this Kekulé structure) belong to this hexagon. We show that in the case of catafusenes, there is a one-to-one correspondence between ordinary and algebraic Kekulé ...
Ivan Gutman, Damir Vukicevic, Ante Graovac, Milan Randic   +3 more
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The Non-Benzenoid Aromatic Hydrocarbon Pentalene

Nature, 1948
IT is an interesting fact that neitherjpentalene (1), nor heptalene (2), nor any derivatives of them have been definitely reported as being synthesized1 or found to occur naturally. Azulene (3) is, on the other hand, a substance which can be made by the established procedures of organic chemistry and it is known in Nature.
D P, CRAIG, A, MACCOLL
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Algebraic Kekulé Formulas for Benzenoid Hydrocarbons

Journal of Chemical Information and Computer Sciences, 2004
By assigning two pi-electrons of CC double bonds in a Kekulé valence structure to a benzene ring if not shared by adjacent rings and one pi-electron if CC double bond is shared by two rings we arrived at numerical valence formulas for benzenoid hydrocarbons.
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Perimeter Topology of Benzenoid Polycyclic Hydrocarbons.

ChemInform, 2005
The equivalence of the perimeter topological equations derived by Dias and the 13 possible modes of hexagon adjacency in fused benzenoid systems subsequently presented by Cyvin, Gutman, and collaborators is shown. The aufbau principle for generation of all fused total resonant sextet (TRS) benzenoid hydrocarbons is proved.
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The evaluation of moments for benzenoid hydrocarbons

Theoretica Chimica Acta, 1995
A systematic derivation of moments for polyhexes is presented, covering the tenth and twelfth members for the first time. The total Huckel π-electron energy is computed in terms of moments with desired precision. Equations governing various molecular fragments are useful for enumerating embeddings of acyclic chains (rooted trees) in polyhexes.
Yuansheng Jiang, Xiaoliang Qian, Yihan Shao   +2 more
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Nonaromatic benzenoid hydrocarbons

Pure and Applied Chemistry, 1990
Abstract
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Conjugated circuits in benzenoid hydrocarbons

Journal of Molecular Structure: THEOCHEM, 1989
Abstract A proof is provided for the previously known result that all conjugated circuits in a benzenoid hydrocarbon are of the size 4m + 2.
I. Gutman, S.J. Cyvin
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Benzenoid rings resonance energies and local aromaticity of benzenoid hydrocarbons

Journal of Computational Chemistry, 2018
In this article, we consider partitioning of the analytical expression for resonance energy (RE) in smaller benzenoid hydrocarbons, to individual benzenoid rings of polycyclic molecules. The analytical expression for molecular RE, available since 1976, is given by the count of all linearly independent conjugated circuit in all Kekulé structures in a ...
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