Remarkable Stabilities of Trimetallic Nitride Clusterfullerenes MSc2N@C70 (M = Sc, Y, Dy) with Three Pentagon Adjacencies: A Theoretical Survey

A MSc2N@C70 (M =Sc, Y, Dy) family has been systematically investigated by density functional calculations in conjunction with statistical thermodynamic analyses for the first time. The results revealed that C2v(7854)-C70 is the most predominant carbon cage when encapsulating DySc2N, YSc2N, and Sc3N clusters. In addition, endohedral structures based on C1(7852)-C70 and C1(7851)-C70 are also stable with large concentrations in the temperature region of fullerene formation. All these three isomers are non-IPR structures with three pentagon adjacencies (PA) and related by Stole-Wales transformation. The interaction energies (INT) of MSc2N@C2v(7854)-C70, MSc2N@C1(7852)-C70, and MSc2N@C1(7851)-C70 are much more negative than those of the IPR structures MSc2N@D5h(8149)-C70, revealing a stabilizing effect of the MSc2N (M=Sc, Y, Dy) clusters toward the PAs. Based on the ionic model of (MSc2N)6+@C706- which is confirmed by the frontier orbital analyses, the electron back-donation from C706- to (MSc2N)6+ increases i...