An unprecedented C-80 cage that violates the isolated pentagon rule

Two Lu2O@C-80 isomers have been successfully isolated and unambiguously assigned as Lu2O@C-1(31876)-C-80 and Lu2O@C-2v(5)-C-80, respectively, by X-ray crystallography. Interestingly, C-1(31876)-C-80 is an unprecedented cage with a pair of adjacent pentagons, which can be closely connected with C-2v(5)-C(80)via a two-step Stone-Wales transformation. More importantly, the C-1(31876)-C-80 cage is a key point in the transformation map of oxide cluster fullerenes, filling the vacancy in the formation process.