Synthesis and structural studies of perfluoroalkyl-rhodium and iridium(iii) compounds containing tris(pyrazolyl)borate ligands

Abstract

Oxidative addition of perfluorobenzyl iodide to TpRh(C2H4)2 [Tp = tris(pyrazolyl)borate] affords TpRh(CF2C6F5)(C2H4)I, from which the ethylene ligand can be displaced by CO to afford TpRh(CF2C6F5)(CO)I. Similar reaction of perfluorobenzyl iodide with TpIr(CO)2 or Tp*M(CO)2 [Tp* = tris(3,5-dimethylpyrazolyl)borate; M = Rh, Ir] affords Tp*M(CF2C6F5)(CO)I. Displacement of CO from the carbonyl complexes using PMe3 is not clean and yields a mixture of compounds. However, displacement of ethylene from TpRh(CF2C6F5)(C2H4)I using PMe3 cleanly affords TpRh(CF2C6F5)(PMe3)I. Similar oxidative addition reactions of perfluoro-n-propyl iodide afford TpIr(C3F7)(CO)I, TpRh(C3F7)(CO)I, Tp*Rh(C3F7)(CO)I, Tp*Rh(C3F7)(PMe3)I, and TpM(C3F7)(C2H4)I [M = Rh, Ir]. While displacement of ethylene from TpRh(C3F7)(C2H4)I by PMe3, to give TpRh(C3F7)(PMe3)I is facile, the corresponding reaction of the iridium analogue affords the salt [TpM(C3F7)(C2H4)(PMe3)]+I−. Ethylene rotation barriers and Co stretching frequencies in these compounds are discussed. The molecular structures of TpIr(CF2C6F5)(CO)I, TpRh(CF2C6F5)(PMe3)I, and TpRh(C3F7)(PMe3)I have been determined, and are also discussed in detail.