Aromaticity of Organic and Inorganic Heterocycles

Heteroaromatic rings are present in many organic molecules. They can be found as part of the core of drugs or agrochemicals and in many important biochemical molecules. The last three centuries have brought important advances in heteroaromatic chemistry. Indeed, the first organic molecules with heteroaromatic rings were already synthesized in the middle of the nineteenth century. Then, the twentieth century witnessed the first inorganic heteroaromatic compound produced in the laboratory. And at the beginning of the present century, the first all-metal heteroaromatic cluster was detected. Here, we discuss the aromaticity of some of these heteroaromatic compounds using different descriptors of aromaticity, with special emphasis in those measures based on electron delocalization properties of the aromatic rings.