ENUMERATION AND CLASSIFICATION OF CORONOID HYDROCARBONS .10. DOUBLE CORONOIDS

A multiple coronoid is a polyhex with more than two corona holes. Double coronoids with two holes are treated most extensively. They are classified into (a) those obtained by additions of hexagons, (b) primitive, (c) nonprimitive basic, and (d) nonbasic extras. This classification is important under the computer-aided specific generation of the double coronoids. A full account is given for the numbers of nonisomorphic double coronoids with the number of hexagons (h) up to 16. Among the 1618 systems with h = 16, the 64 systems under the categories (b), (c), and (d) are described extensively, and their forms are depicted. Machine-computed Kekulé structure counts are reported for many double coronoids, and for some of them also an analytical solution according to the method of fragmentation is shown. Some features of triple coronoids (three holes) are included. © 1990, American Chemical Society. All rights reserved.