https://doi.org/10.1351/goldbook.A00249
A
![Not defined](/img/inline/A00249-2.png)
conjugated system
of π-electrons is termed alternant if its atoms can be divided into two sets so that no atom of one set is directly linked to any other atom of the same set. ![Not defined](/img/inline/A00249-1.png)
![Not defined](/img/inline/A00249-2.png)