Addition of Br-2 or 12 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 Br-2 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.