Cyclopentadienyl and imide ligand transfer from zirconium to iridium: Can early transition metal imido compounds be used as imide transfer reagents?

Instead of leading to imido group transfer, treatment of [Cp*Ir(thf)(3)][OTf](2) with Cp2Zr((NBu)-Bu-t)(thf) (Cp* = C5Me5; Cp = C5H5) gave cyclopentadienyl transfer from Zr to Ir. To characterize the product of this type of reaction more completely, reaction of the corresponding ethyl-substituted compound [(C5Me4Et)Ir(thf)(3)][OTf](2) with the imidozirconium complex was also carried out. This led to [(CpIrCp)-Ir-Et][CpZr((NHBu)-Bu-t)(OTf)(3)(thf)], which has been crystallographically characterized. An X-ray study of the known pentamethyliridocenium salt [Cp*IrCp][BF4] was also performed. In contrast to the above chemistry, the reaction of Cp*Ir-OCMe2CMe2O with Cp2Zr((NBu)-Bu-t)(thf) gives the heterobinuclear bis(imido) complex Cp*Ir(mu-(NBu)-Bu-t)(2)ZrCp2. Thus, in none of these reactions was transfer of the imido group away from the zirconium center observed.