Intramolecular Csp³-H Activation at a Platinum(IV) Center Resulting from O₂ Activation: The Role of a Proton-Responsive Ligand and Trans Influence

Abstract

Aerobic oxidation of a dimethylplatinum(II) complex featuring 1,1-di(2-pyridyl)ethanol as a supporting ligand leads to the formation of two unexpected Pt IV complexes (in ∼1:1 ratio), neither of which results from direct oxidation typical for Pt II centers supported by popular κ 2 -(N,N) ligands. While one product features an isomerized Pt IV center stabilized by the κ 3 -(N,N,O) ligand coordination mode, surprisingly, the other product results from intramolecular activation of the ligand methyl fragment. Mechanistic studies, reactivity of model complexes, and DFT calculations reveal that the critical proton-responsive nature of the ligand allows formation of intermediates that result in a concerted metalation deprotonation (CMD)-like C−H activation at Pt IV . To the best of our knowledge, this is the first mechanistic delineation of Csp 3 -H activation at Pt IV , despite being known for other highvalent platinum group metal centers.