Electrophilic Fluorination of Organoplatinum(II) Iodides: Iodine and Platinum Atoms as Competing Fluorination Sites

A series of diphosphine Pt­(II) aryl iodo complexes were
reacted
with XeF2 to cleanly produce the corresponding Pt­(II) difluoro
complexes and free iodoarenes. However, when aryl ligands bearing
fluoro substituents in the ortho positions were used, the formation
of the corresponding Pt­(II) aryl fluoro complexes was observed in
the reaction with XeF2. In the case of the Pt–C6F5 complex, the products of the fluoride-for-iodide
exchange were the only products observed by means of 31P and 19F NMR spectroscopy. The experimental and theoretical
studies suggest that the formation of iodine–fluorine bond
may accompany this transformation. The plausible “I–F”
species could be trapped by electron-richer organoplatinum complexes
to give a Pt­(IV) transient which subsequently eliminates the corresponding
aryl iodide. Hence, in some cases a pathway involving an attack of
XeF2 at the iodo ligand of Pt­(II) aryl iodo complexes to
generate I–F species can be operative in addition to or instead
of the XeF2 attack at the metal center. Our DFT studies
demonstrate that the electrophilic attacks of XeF2 at both
sites, platinum and iodide, can be competitive.