Fulvenes are a class of organic compounds characterized by a five-membered ring containing two double bonds. They are part of the broader category of polycyclic aromatic hydrocarbons and are known for their unique structural properties, which can influence their chemical reactivity and stability. These compounds can be synthesized through various chemical reactions and are of interest in fields such as organic chemistry and materials science. Their distinct properties make them useful in applications like organic electronics and as intermediates in the synthesis of more complex molecules.