Encapsulation and dynamic behavior of two H2 molecules in an open-cage C70.

An open-cage C70 derivative having a 13-membered ring opening (2) was synthesized by a three-step reaction; thermal reaction of C70 with a pyridazine derivative, oxidative cleavage of the CC double bond, and insertion of a sulfur atom to the opening. The structure of 2 was determined by X-ray analysis. One H2 molecule was introduced into 2 to give H2@2 in 97% yield. Furthermore, two H2 molecules were encapsulated in 2 in 3% yield. The positional exchange of two H2 molecules inside 2 was clearly observed by the dynamic low-temperature NMR measurements.