Deviation from the planarity--a large Dy3N cluster encapsulated in an Ih-C80 cage: an X-ray crystallographic and vibrational spectroscopic study.

The high-yield synthesis of Dy3N@C80 (I) opens the possibility of characterizing its molecular and vibrational structures. We report on the structure determination of Dy3N@C80 (I) by X-ray crystallographic study of single crystal of Dy3N@C80.Ni(OEP).2C6H6, revealing a nearly planar Dy3N cluster encapsulated in an Ih-C80 cage. The vibrational structure of Dy3N@C80 (I) is studied by Fourier transform infrared (FTIR) and Raman spectroscopy in combination with force-field calculations. A correlation was found between the antisymmetric metal-nitrogen stretching vibration and the structure of the M3N cluster of M3N@C80 (I) (M = Y, Gd, Tb, Dy, Ho, Er, Tm). Moreover, a stronger interaction between the encaged nitride cluster and the C80 carbon cage was found in the class II M3N@C80 (I) (M = Y, Gd, Tb, Dy, Ho, Er, Tm) than in Sc3N@C80 (I). This study demonstrates that the cluster size plays the dominating role in the structure of the M3N cluster in M3N@C80 (I).