Carbon atoms trapped in cages: Metal carbide clusterfullerenes

• An exhaustive survey of recent research progress of metal carbide clusterfullerenes (MCCFs).
• A detailed enumeration of structural establishments of representative MCCFs.
• Novel structures, intriguing cluster–cage interplays, and exohedral reactivity.
• Fascinating properties and potential applications.

Metal carbide clusterfullerenes (MCCFs), which trap two carbon atoms together with metal atom(s) inside the fullerene cage, are a novel branch of endohedral metallofullerenes (EMFs). This review presents an exhaustive survey of recent research progress in MCCFs. After a detailed enumeration of the structural establishments of representative MCCFs, their novel structures, intriguing cluster–cage interplays, fascinating properties, and potential applications are highlighted. Moreover, a variety of new MCCF members are suggested for future identification.