Formation of C–X Bonds through Stable Low-Electron-Count Cationic Platinum(IV) Alkyl Complexes Stabilized by N‑Heterocyclic Carbenes

Cationic five-coordinate Pt­(IV) alkyl
complexes stabilized by bulky
N-heterocyclic carbenes have been isolated and fully characterized.
Related species have been postulated as key intermediates in carbon–heteroatom
coupling reactions and most particularly in Shilov-type chemistry.
The alkyl groups exhibit a pronounced electrophilic character and
can undergo nucleophilic addition of pyridine, bromide, or iodide
to form new carbon–heteroatom bonds. Nevertheless, direct reductive
coupling to form C–X bonds can be operative in the absence
of an external nucleophile source.