Five-Coordinate Platinum(IV) Complexes

Octahedral organometallic platinum(IV) complexes have been known for more than a century. Mechanistic studies suggest that many reactions of these six-coordinate platinum(IV) complexes proceed through unobservable five-coordinate platinum(IV) intermediates. Only recently have five-coordinate platinum(IV) complexes been isolated and characterized. These novel complexes serve as models for unobserved intermediates in stoichiometric and catalytic reactions involving high oxidation state platinum. The isolation of five-coordinate complexes allows the unique reactivity of these unsaturated species to be investigated directly. This contribution describes the development of five-coordinate platinum(IV) from proposed intermediates to isolable complexes. The syntheses, characterization, and reactivity studies of complexes with this new coordination geometry of platinum(IV) are also presented.