ISSN:
1572-9001
Keywords:
Hydrocarbon
;
helicene
;
chemical formula
;
extremal helicene
;
formula index
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The formulas C n H s ≡ (n; s) for helicenic hydrocarbons are treated. The restrictions onn ands are specified comprehensively in terms of inequalities. General expressions are given for the C n H s formulas of extremal helicenes and some of their subclasses: circumextremal- and circular helicenes. Sequences of formulas for extremal helicenes, viz. (n 0; s0), (n 1; s1), ..., (n k; sk), ..., are defined. Here (n 0;s 0) is said to represent ground-form helicenes, while (n k; sk) for k 〉 0 pertain to higher members. A higher member with the formula (n k; sk) is an extremal helicene which can be obtained byk-fold complete sedimentation of a ground form. This process corresponds to circumscribing of benzenoids. A formula index, viz.x as a function ofn ands, distinguishes different classes of helicenes and can be used to identify the formulas for ground forms and higher members. The possible C n H s formulas for helicenes and their indices are tabulated. Finally the numbers of edges in C n H s isomers are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00681204
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