Category 2: Five-Membered Hetarenes with Three or More Heteroatoms (Vol 13)

Nearly a hundred different ring systems are included in this volume: a clear indication of the variety of possible structures that can be formed by including three or more heteroatoms in a five-membered ring. Some of these rings systems, such as the thiadiazoles, triazoles, and tetrazoles, are common and stable structures with hundreds of known deriva-tives, whereas others, such as the thiatriazoles and pentazoles, are thermally unstable species with little known chemistry.