Ground form single coronoid

Fig. 6.2. Two isomers of the non-circular G systems imperfect ground form single coronoids.

The focussing on formulas for single coronoids is continued in this chapter. It starts with a treatment of sequences of associated formulas for extremal single coronoids. This study leads to another subdivision of the extremal coronoids ground forms and higher members. The pertinent sections can be considered as a preparation to the enumeration of coronoid isomers, which is treated in the subsequent chapter. Also the process of building-up (Sect. 6.5) is highly relevant to the enumeration of isomers. 

For extremal single coronoids we shall define ground forms and higher members in connection with a sequence of formulas (uq Sq), (n . , (nj. in analogy with the... 

DefimUian 6.1 A ground form (of single coronoids), G, is an extremal single coronoid which is not drcumextremal. 

Table 6.1. Fonnula for the first (smallest) ground forms of single coronoids (G) and their associated benzenoids (A) ...

Definition 6.4 . (a) A perfect higher member (of single coronoids) is defined by having the same formula as a Wold k > 1) circumscribed perfect ground form, (b) An imperfect higher member has the same formula as a A —fold circumscribed imperfect ground form. 

Fig. 6.1. The smallest perfect ground forms of single coronoids, aumented bv two...

Figure 3 shows a dot diagram for the formulas of single coronoids as in Fig. 5.8. However, more detailed information about the extremal (A) systems is included formulas for ground forms and higher members, both perfect and imperfect, are indicated.

Property 6.S An imperfect ground form or a circumextremal single coronoid, A, has neither an L — or P2—Taode hexagon. 

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