As one of the most extensively dispersed elements in the universe, carbon can exist in many forms, which are known as carbon allotropes. In recent years, carbon materials of sp 2 -hybridization, such as fullerenes , carbon nanotubes , and graphene , have attracted much attention and have played a role in many applications. However, molecules with sp-hybridized carbon, such as chain and ring structures, are more elusive. Direct configuration observation and property determination of these dicoordinated carbon clusters have always been considered a great challenge due to their extremely high sensitivity against oxygen and strong tendency to covalent coupling.