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Open-cage fullerenes, fullerenes with orifices created by breaking some of the C-C bonds in a fullerene such as C60, are molecules that allow chemical access to both the external and the internal surfaces of the carbon cage. We have found such molecules to be challenging to crystallize and thereby fully structurally characterize through single crystal X-ray diffraction studies. We have also found that the reactivity of these open cage fullerenes can differ significantly from that of the parent fullerene (see A. Aghabali, S. Jun, M. M. Olmstead, A. L. Balch, Silver(I)-Mediated Modification, Dimerization, and Polymerization of an Open-Cage Fullerene. J. Am. Chem. Soc. 2016, 138, 16459-16465.) This talk will report recent studies of the crystallographically determined structures and reactivities of several open-cage fullerenes with particular attention given to the accessibility of the cage opening to chemical reactions.

The structure of Sc3N@D 3h -C78, which has been examined crystallographically and found to obey the isolated pentagon rule (IPR), will be discussed and compared to other related endohedral fullerenes. The effect of the composition of the interior M3N unit in this and other endohedral fullerenes will be shown to influence cage structure, sometimes in a predictable fashion. Structural studies of other fullerenes will also be presented.

Cocrystallization of endohedral fullerenes and empty cage fullerenes with Ni(octaethylporphyrin) has become a widely used method to obtain X-ray structural information on these molecules. However, the stoichiometry of composition of these materials is difficult to predict. here we will report some new structures and studies of factors that effect the composition of these cocrystals.