The endohedral fullerene CH 4 @C 60 , in which each C 60 fullerene cage encapsulates a single methane molecule, has been synthesized for the first time. Methane is the first organic molecule, as well as the largest, to have been encapsulated in C 60 to date. The key orifice contraction step, a photochemical desulfinylation of an open fullerene, was completed, even though it is inhibited by the endohedral molecule. The crystal structure of the nickel(II) octaethylporphyrin/ benzene solvate shows no significant distortion of the carbon cage, relative to the C 60 analogue, and shows the methane hydrogens as a shell of electron density around the central carbon, indicative of the quantum nature of the methane. The 1 H spin‐lattice relaxation times ( T 1 ) for endohedral methane are similar to those observed in the gas phase, indicating that methane is freely rotating inside the C 60 cage. The synthesis of CH 4 @C 60 opens a route to endofullerenes incorporating large guest molecules and atoms.

An open-cage fullerene incorporating phosphorous ylid and carbonyl group moieties on the rim of the orifice can be filled with gases (H 2 ,He, Ne) in the solid state,and the cage opening then contracted in situ by raising the temperature to complete an intramolecular Wittig reaction, trapping the atom or molecule inside.K nown transformations complete conversion of the product fullerene to C 60 containing the endohedral species.A sw ell as providing an improved synthesis of large quantities of 4 He@C 60 ,H 2 @C 60 ,and D 2 @C 60 ,the method allows the efficient incorporation of expensive gases such as HD and 3 He,t op repare HD@C 60 and 3 He@C 60 .T he method also enables the first synthesis of Ne@C 60 by molecular surgery,and its characterization by crystallography and 13 CNMR spectroscopy.

The interactions between atoms and molecules may be described by a potential energy function of the nuclear coordinates. Nonbonded interactions between neutral atoms or molecules are dominated by repulsive forces at a short range and attractive dispersion forces at a medium range. Experimental data on the detailed interaction potentials for nonbonded interatomic and intermolecular forces are scarce. Here, we use terahertz spectroscopy and inelastic neutron scattering to determine the potential energy function for the nonbonded interaction between single He atoms and encapsulating C 60 fullerene cages in the helium endofullerenes 3 He@C 60 and 4 He@C 60 , synthesized by molecular surgery techniques. The experimentally derived potential is compared to estimates from quantum chemistry calculations and from sums of empirical two-body potentials.

Synthesis of Ar@C60 is described, using a route in which high-pressure argon filling of an open-fullerene and photochemical desulfinylation are the key steps for >95% encapsulation of the noble gas....