How many organic compounds are graph-theoretically nonplanar?
Christoph Rücker, Markus Meringer · 2002
INTRODUCTION In computer-assisted structure elucidation, e.g. of natural products, a graph generator is used to construct all possible candidate structures (colored multigraphs) for a given molecular formula under a set of restrictions derived from various spectroscopic measurements. Often one is confronted with a very large number of candidates, therefore further restrictions are urgently needed. For an unknown containing more than three cycles (and these are the more difficult problems), as a rule many of the candidate structures are gt-nonplanar, whereas many chemists feel that gt-nonplanar compounds are rare. 1 The term gt-nonplanar (short for graph- theoretically nonplanar) means that the constitutional formula (structural formula) of such a compound cannot be drawn in a plane without at least two bonds crossing. Most known 154 compounds, even geometrically decidedly nonplanar ones such as helicenes, fullerenes, and most other synthesized polycyclic structures