Reaction of the organoplatinum complex [Pt(COD)(neoPh)Cl] (neoPh = (2-methyl-2-phenylpropyl)) with Ag(PF₆) leads to the undercoordinated cationic complex [Pt(COD)(neoPh)]⁺ which rapidly and quantitatively rearranges to the complex [Pt(COD)(κ²-neoPh)] through intramolecular cyclometalation. Detailed NMR spectroscopy and single crystal XRD reveal a doubly metalated neoPh ligand. In line with experimental observations, ab initio molecular dynamics simulations confirm that the cyclometalation reaction is exothermic and has a relatively low free energy barrier. In addition, the simulations provide detailed insight into the reaction mechanism, showing that an intermediate species exists in which the newly formed Pt–C bond coexists with a covalent Pt–H bond involving the leaving proton. The latter is found to eventually transfer onto an acetone solvent molecule.