Putting Atoms and Molecules into Chemically Opened Fullerenes

Abstract

We studied Ar, Kr, CO, and N(2) going into and out of a chemically opened fullerene, 1. We measured the equilibrium constant, K(eq), for the formation of X@1. K(eq) is particularly large for Ar, probably due to the large van der Waals attraction between the Ar atom and the fullerene cage. We measured rate constants and activation energies for the unimolecular reaction X@1-->X + 1 (X = Ar, CO, N(2)). The reactions show an unusually small pre-exponential factor, probably due to the loose binding of X inside the cage.

Synthesis and Properties of Open Fullerenes Encapsulating Ammonia and Methane

“…From the linear Arrhenius and Eyring plots (Figure ), an activation energy of 134.6±5.0 kJ mol −1 and pre‐exponential factor log(A) of 10.9 was determined. The latter is low for a unimolecular reaction, but comparable for those previously observed for loss of endohedral atoms and molecules from endohedral fullerenes . The enthalpy and entropy of activation for CH 4 loss were determined to be Δ H ≠ =131.0±5.0 kJ mol −1 and Δ S ≠ =−47.0±11.2 J K −1 mol −1 giving a Δ G ≠ at 165 °C of 151.5±0.1 kJ mol −1 .…”

Preparation of Open‐Cage Fullerenes and Incorporation of Small Molecules Through Their Orifices

“…For the selenium-inserted derivative 41b, milder conditions (760 atm and 190 8C) [50] were needed than for the sulfur-inserted compound 41a (800 atm and 200 8C). [59] So far the following molecules have been incorporated into open-cage fullerene derivatives: He, [58,60] H 2 , N 2 , [61] CO, [62] H 2 O, [44,49,57] NH 3 , [63] and CH 4 . [64] Owing to the size of the cavity, only one molecule was incorporated in the C 60 open-cage derivatives.…”

Inelastic neutron scattering investigations of the quantum molecular dynamics of a H2molecule entrapped inside a fullerene cage

“…In addition to the increasing literature on the chemical principles [5,6,7,8,9,10,11,12], spectroscopic investigations using infra-red (IR) [3,13,14,15], inelastic neutron scattering (INS) [3,16,17] and nuclear magnetic resonance (NMR) [3,18,19] have probed the physical characteristics of these complexes. Also, heat capacity measurements have identified a small splitting of the rotational line associated with the symmetry of the crystal field, a first indication of inter-fullerene contributions to the effective cage potential [20].…”