Ab initio helium NMR chemical shifts of endohedral fullerene compounds He@C_n (n = 32−180)

Helium NMR chemical shifts have been computed at the gauge including atomic orbitals (GIAO)-SCF/dz(C), tzp(He)//MNDO level for the endohedral fullerene compounds He@Cn (n = 32, 36, 50, 60, 70, 76, 78, 80, 82, 120, 180). The endohedral He shielding increases in the sequence C60 84 82 78 76 70, in accord with recent London calculations. For the smaller fullerenes (n 50 (D5h), while a nearly constant endohedral chemical shift of ≈ −17 ppm is predicted for the symmetric large fullerenes C120 and C180