Aryl-halide versus aryl-aryl reductive elimination in Pt(IV)-phosphine complexes

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Catalysis

Background:

• Platinum complexes with bidentate phosphine ligands are versatile in synthetic chemistry.
• Understanding reactivity patterns is crucial for designing new catalytic processes.
• The influence of ligand bite angle on metal complex reactivity is a key area of study.

Purpose of the Study:

• To investigate the reaction of bromine (Br2) with platinum(II) aryl complexes featuring bidentate phosphine ligands.
• To determine how the bite angle of the phosphine ligand influences the reaction pathway and product formation.
• To explore the thermal behavior of the observed platinum complexes and their subsequent transformations.

Main Methods:

• Synthesis of platinum(II) aryl complexes with varying bidentate phosphine ligands.
• Reaction of the platinum complexes with elemental bromine (Br2).
• Characterization of reaction products using spectroscopic techniques (e.g., NMR) and X-ray crystallography.
• Thermal treatment of platinum(IV) complexes to study reductive elimination.

Main Results:

• Two distinct product types were observed upon Br2 addition: a Pt(II) aryl bromide complex and a Pt(IV) oxidative addition complex.
• The formation of either Pt(II) or Pt(IV) product was directly correlated with the bite angle of the bidentate phosphine ligand.
• At elevated temperatures, the Pt(IV) complex exclusively underwent C-C reductive elimination to form a new product.

Conclusions:

• The bite angle of bidentate phosphine ligands is a critical determinant in controlling the outcome of bromine addition to Pt(II) aryl complexes.
• This study reveals a switchable reactivity pathway, leading to either C-Br reductive elimination or oxidative addition.
• The Pt(IV) intermediates are capable of undergoing C-C reductive elimination at high temperatures, offering a route to new C-C bond formation.