Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Molecular structure of Dy₃N@C₇₈ and Tm₃N@C₇₈ clusterfullerenes are addressed by the IR and Raman vibrational spectroscopic studies and DFT computations. Firstly, extensive semiempirical calculations of 2927 isomers of C₇₈ hexaanions followed by DFT optimization were applied to establish their relative stability. Then, DFT calculations of a series of M₃N@C₇₈ (M=Sc, Y, Lu, La) isomers were performed which have shown that the stability order of the isomers depends on the cluster size. While the Sc₃N cluster is planar in the earlier reported Sc₃N@C₇₈ (D_3h: 24109) clusterfullerene, relatively large Y₃N and Lu₃N clusters would be forced to be pyramidal inside this cage, which would result in their destabilization. Instead, these clusters remain planar in the non-IPR C₂: 22010 isomer making Y₃N@C₇₈ and Lu₃N@C₇₈ clusterfullerenes with this cage structure the most stable ones. Finally, on the basis of a detailed analysis of their IR and Raman spectra supplemented with DFT vibrational calculations, the recently isolated Tm₃N@C₇₈ and the major isomer of Dy₃N@C₇₈ are assigned to the non-IPR C₂: 22010 cage structure. A detailed assignment of their experimental and computed IR and Raman spectra is provided to support this conclusion and to exclude other cage isomers.