Origin of the Rate Acceleration in the C−C Reductive Elimination from Pt(IV)-complex in a [Ga₄L₆]¹²⁻ Supramolecular Metallocage

The reductive elimination on [(Me₃P)₂Pt(MeOH)(CH₃)₃]⁺, 2P, complex performed in MeOH solution and inside a [Ga₄L₆]¹²⁻ metallocage are computationally analysed by mean of QM and MD simulations and compared with the mechanism of gold parent systems previously reported [Et₃PAu(MeOH)(CH₃)₂]⁺, 2Au. The comparative analysis between the encapsulated Au(III) and Pt(IV)-counterparts shows that there are no additional solvent MeOH molecules inside the cavity of the metallocage for both systems. The Gibbs energy barriers for the 2P reductive elimination calculated at DFT level are in good agreement with the experimental values for both environments. The effect of microsolvation and encapsulation on the rate acceleration are evaluated and shows that the latter is far more relevant, conversely to 2Au. Energy decomposition analysis indicates that the encapsulation is the main responsible for most of the energy barrier reduction. Microsolvation and encapsulation effects are not equally contributing for both metal systems and consequently, the reasons of the rate acceleration are not the same for both metallic systems despite the similarity between them.