Nanoscale Fullerene Compression of an Yttrium Carbide Cluster

The nanoscale parameters of metal clusters and lattices have a crucial influence on the macroscopic properties of materials. Herein, we provide a detailed study on the size and shape of isolated yttrium carbide clusters in different fullerene cages. A family of diyttrium endohedral metallofullerenes with the general formula of Y2C2n (n = 40–59) are reported. The high field 13C nuclear magnetic resonance (NMR) and density functional theory (DFT) methods are employed to examine this yttrium carbide cluster in certain family members, Y2C2@D5(450)-C100, Y2C2@D3(85)-C92, Y2C2@C84, Y2C2@C3v(8)-C82, and Y2C2@Cs(6)-C82. The results of this study suggest that decreasing the size of a fullerene cage with the same (Y2C2)4+ cluster results in nanoscale fullerene compression (NFC) from a nearly linear stretched geometry to a constrained “butterfly” structure. The 13C NMR chemical shift and scalar 1JYC coupling parameters provide a very sensitive measure of this NFC effect for the (Y2C2)4+ cluster. The crystal structur...