Classes of Basic Benzenoids (IV): Rectangles

Abstract

A class of rectangle-shaped benzenoids or rectangles, which has the main symbol R, consists of straight regular strips; cf. Chapter 10. Both rims are (single) zigzag chains. We distinguish between a prolate rectangle, Rⁱ (m,n), and an oblate rectangle, R^j (m,n), which possess an inward or outward indentation, respectively; cf. Fig. 1. They are (2m−1)-tier strips. The cases of 5-tier strips (m=3) are found as No. I-14 (Rⁱ) and No. I-6 (R^j) in Table 10.5. Figure 1 shows Rⁱ (4,4) and R^j (3,3), a 7-tier and a 5-tier regular strip, respectively. An intermediate system is identified as a non-regular 6-tier strip (see Fig. 1); it is an obvious non-Kekuléan.