Chlorination-promoted Transformation of Isolated Pentagon Rule C78 into Fused-pentagons- and Heptagons-containing Fullerenes.

Cage transformations in fullerenes are rare phenomena which are still not fully understood. We report the first skeletal transformation of an Isolated-Pentagon-Rule (IPR) isomer of C78 fullerene upon high-temperature chlorination which proceeds by six-step Stone-Wales rearrangements affording non-IPR, non-classical (NC) C78 (NC2)Cl24 with two cage heptagons, six pairs of fused pentagons, and an unprecedented loop-like chlorination pattern. The following loss of a C2 unit results in C76 (NC3)Cl24 containing three cage heptagons.