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Monometallic cyanide clusterfullerenes (CYCFs) represent a unique branch of endohedral clusterfullerenes with merely one metal atom encapsulated, offering a model system for elucidating structure-property correlation, while up to now only C 82 and C 76 cages have been isolated for the pristine CYCFs. C 84 is one of the most abundant fullerenes and has 24 isomers obeying the isolated pentagon rule (IPR), among which 14 isomers have been already isolated, whereas the C 2 v (17)-C 84 isomer has lower relative energy than several isolated isomers but never been found for empty and endohedral fullerenes. Herein, four novel C 84 -based pristine CYCFs with variable encapsulated metals and isomeric cages, including MCN@ C 2 (13)-C 84 (M = Y, Dy, Tb) and DyCN@ C 2 v (17)-C 84 , have been synthesized and isolated, fulfilling the first identification of the missing C 2 v (17)-C 84 isomer, which can be interconverted from the C 2 (13)-C 84 isomer through two steps of Stone-Wales transformation. The molecular structures of these four C 84 -based CYCFs are determined unambiguously by single-crystal X-ray diffraction. Surprisingly, although the ionic radii of Y 3+ , Dy 3+ , and Tb 3+ differ slightly by only 0.01 Å, such a subtle difference leads to an obvious change in the metal-cage interactions, as inferred from the distance between the metal atom and the nearest hexagon center of the C 2 (13)-C 84 cage. On the other hand, upon altering the isomeric cage from DyCN@ C 2 (13)-C 84 to DyCN@ C 2 v (17)-C 84 , the Dy-cage distance changes as well, indicating the interplay between the encapsulated DyCN cluster and the outer cage. Therefore, we demonstrate that the metal-cage interactions within CYCFs can be steered via both internal and external routes.