U2N@Ih(7)-C80: fullerene cage encapsulating an unsymmetrical U(iv)NU(v) cluster

A novel actinide cluster, UNU, is stabilized inside a C 80 fullerene cage. The U( iv )NU( v ) cluster features two UN bonds with uneven bond distances of 2.058(3) Å and 1.943(3) Å, leading to an unsymmetrical structure.