The diiridium complexes of lithium-ion endohedral fullerene Li+@C60 were synthesised in high yields. X-ray crystallography revealed the η2:η2-coordination of Li+@C60 and the disorder of the Li+ ion over two sites close to the coordinated carbons. 13C NMR study suggested the presence of dynamic behaviour via haptotropic rearrangements. UV/Vis and CV characteristics were also investigated experimentally and theoretically.