New Route to Cycloplatinated N-Heterocyclic Carbene Complexes via Iodide Assisted C-H Activation and Proton Transfer

Abstract

A convenient strategy to access cyclometalated platinum (II) N-heterocyclic carbene (NHC) complexes is reported herein, synthesized by treating a Pt (NHC)I₂Py precursor with Schiff-base (N^O) ligands in the presence of K₂CO₃ base under mild reaction conditions. These cyclometalated Pt(II) NHC complexes were fully characterized by ¹H and ¹³C NMR, mass spectrometry, and infrared spectroscopies, and the solid-state molecular structures of complexes 1, 2b, and 3b were unambiguously determined by single-crystal X-ray diffraction methods. To form these complexes, C-H bond activation and C-N cleavage and cycloplatination had to occur. In a bid to understand this transformation, density functional theory was carried out to rationalize the cycloplatination mechanism unveiling an intriguing anion assisted C-H activation and proton transfer process.