Collision-induced dissociation (CID) patterns of the phosphine-protected Au-based clusters [PdAu(PPh)] () and [Au(PPh)] (), featuring crown-shaped M@Au (M = Pd, Au) cores, were investigated. For , ordinary sequential PPh losses ( → [PdAu(PPh)] + (8 - )PPh ( = 7, 6, 5)) were observed. In contrast, underwent cluster-core fission ( → [Au(PPh)] () + [Au(PPh)] ()) upon sufficiently high energy collision, associated with splitting the number of valence electrons in the superatomic orbitals from 6e () into 4e () and 2e (). Density functional theory calculations revealed oblate and prolate cores of and with semiclosed superatomic electron configurations of (1S)(1P)(1P) and (1S)(1P), respectively. This result indicated a significant deformation of the cluster-core motif during the CID process. We attribute the clear difference between and to the softer Au-Au bond in and propose that the collision-induced structural deformation plays a critical role in the fission.
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