An optimised scalable synthesis of H2O@C60 and a new synthesis of H2@C60.

New high-yielding synthetic routes to the small-molecule endofullerenes H2O@C-60, D2O@C-60 and H-2@C-60 are described. The use of high temperatures and pressures for the endohedral molecule incorporation are avoided. A new partial closure step using PPh3, and final suturing using a novel Diels-Alder/retro-Diels-Alder sequence are amongst the advances reported.