Endohedral metallofullerene Sc3NC@C84: a theoretical prediction

Abstract

Very recently, two novel Sc₃NC-based cluster fullerenes Sc₃NC@C₈₀ (Wang et. al. J. Am. Chem. Soc. 2010, 132, 16362) and Sc₃NC@C₇₈ (Wu et. al. J. Phys. Chem. C 2011, 115, 23755) were prepared and characterized, respectively. Inspired by these findings, the possibility of encapsulating Sc₃NC cluster in the C₈₄ fullerene is performed using density functional theory (DFT). Firstly, the isolated pentagon rule (IPR) D_2d (23) C₈₄ fullerene is employed to encase the Sc₃NC cluster: four possible endohedral metallofullerene isomers a–d are designed. The large binding energies (ranging from 163.7 to 210.0 kcal mol⁻¹) indicate that the planar quinary cluster Sc₃NC can be stably encapsulated in the C₈₄ (isomer 23) cage. Further, we consider the incorporation of Sc₃NC into the non-IPR C_s (51365) C₈₄ cage leading to isomer e and show the high stability of isomer e, which has a larger binding energy, larger HOMO-LUMO gap, higher adiabatic (vertical) ionization potential, and lower adiabatic (vertical) electron affinity than the former four Sc₃NC@C₈₄ (isomer 23). Significantly, the predicted binding energy (294.2 kcal mol⁻¹) of isomer e is even larger than that (289.2 and 277.7 kcal mol⁻¹, respectively) of the synthesized Sc₃NC@C₈₀ and Sc₃NC@C_78, suggesting a considerable possibility for experimental realization. The ¹³C NMR chemical shifts and Raman spectra of this a new endofullerene have been explored to assist future experimental characterization.