Cyclometalated Platinum Compounds from Competing C-H/C-X Bond Activation Pathways

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Photochemistry

Background:

• Platinum complexes are vital in catalysis and materials science.
• Understanding reactivity pathways of platinum precursors is crucial for designing new functional molecules.
• Cyclometalated ligands offer unique electronic and steric properties.

Purpose of the Study:

• To investigate the reactivity of [Pt2Me4(μ-SMe2)2] with X-C^N^N ligands (X = Br, Cl).
• To characterize the resulting platinum(IV) and platinum(II) products.
• To explore the photophysical properties and reaction mechanisms using computational methods.

Main Methods:

• Synthesis of platinum complexes.
• Multinuclear NMR spectroscopy and single-crystal X-ray diffraction (SCXRD) for structural characterization.
• UV/vis, emission, and transient absorption (TA) spectroscopies for photophysical studies.
• Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT) calculations.

Main Results:

• Reaction with X=Br yielded a six-coordinate cyclometalated platinum(IV) complex with an anionic C^N^N ligand.
• Reaction with X=Cl produced both platinum(IV) and platinum(II) products.
• The platinum(II) species formed via C-H activation and reductive elimination of methane.
• Experimental and computational results were compared to elucidate reaction pathways.

Conclusions:

• The reactivity of platinum precursors is sensitive to the nature of the ancillary ligand (X-C^N^N).
• C-H activation is a viable pathway for forming platinum(II) species from platinum(IV) intermediates.
• Spectroscopic and computational methods provide complementary insights into complex reaction mechanisms.