Characterization of a Paramagnetic, Mononuclear Pt(III)–Alkyl Complex Intermediate in Carbon–Halogen Bond Coupling Reactions

Addition of Br2 or I2 to 14-electron, cationic Pt(II)-alkyl complexes led to the formation of the corresponding carbon–halogen Pt(II) coupling products. Low temperature experiments with Br2 allowed us to isolate and characterize crystallographically a very unusual mononuclear, paramagnetic Pt(III)-alkyl intermediate with a seesaw structure that can be further oxidized to a transient Pt(IV) species before reductive carbon–halogen coupling reaction takes place.