Metalloborospherene Analogs to Metallofullerene

Boron, the neighbor element to carbon in the periodic table, is characterized by unique electron deficiency that fosters multicenter delocalized bonding, contributing to its diverse chemistry. Unlike carbon cages (fullerenes), which preserve their structural integrity under endohedral or exohedral doping, larger boron cages (borospherenes) exhibit diverse structural configurations. These configurations can differ from those of pure boron cages and are stabilized by various metals through unique metal–boron bonding, resulting in a variety of metalloborospherenes. Due to boron’s electron deficiency, metalloborospherenes exhibit fascinating chemical bonding patterns that vary with cluster size and the type of metal dopants. This review paper highlights recent advancements in metalloborospherene research, drawing comparisons with metallofullerenes, and focuses on the use of transition metals, lanthanides, and actinides as dopants across various cage dimensions.