Tetrafluoroethyl complexes of iridium(III) derived from a tetrafluoroethylene complex of iridium(I). A study of α-fluoride abstraction and determination of the structure of IrCl 2(CF 2CF 2Cl)(CO)(PPh 3) 2

Abstract

Treatment of the tetrafluoroethylene complex, IrCl(η 2-C 2F 4)(PPh 3) 2, ( 1), with HCl or Cl 2 gives IrCl 2(CF 2CF 2H)(PPh 3) 2 ( 2) or IrCl 2(CF 2CF 2 Cl)(PPh 3) 2 ( 3), respectively. These coordinately unsaturated complexes react with various neutral ligands to give stable, six-coordinate, tetrafluoroethyl and halotetrafluoroethyl complexes. The single crystal X-ray structure of one of these compounds, the carbonyl derivative of ( 3), IrCl 2(CF 2CF 2Cl)(CO)(PPh 3) 2 ( 15) was determined. The acetonitrile derivative of ( 2), IrCl 2(CF 2CF 2H)(CH 3CN)(PPh 3) 2 ( 17) undergoes a reaction with HCl that proceeds through the intermediate fluorocarbene complex, [IrCl 2(=CFCF 2H)(CH 3CN) (PPh 3)] + ( 18), to give, upon hydrolysis, IrCl 2(C[O]CF 2H)(CH 3CN)(PPh 3) 2 ( 19). The acetonitrile ligand, by virtue of its position trans to the acyl group, can be thermally displaced from ( 19) to give IrCl 2(C[O]CF 2H)(PPh 3) 2 ( 20). The vacant coordination site in ( 20) can be filled by other neutral ligands. Thermal treatment of any of the acyl complexes results finally in a reverse migration process and formation of IrCl 2(CF 2H)(CO)(PPh 3) 2 ( 23).