Iridium(III) and Rhodium(III) compounds of dipyridyl-N-alkylimine and dipyridyl-NH-ketimine: Spectral characterization and crystal structure

Pentamethylcyclopentadienyl iridium(III) and rhodium(III) complexes of formulation [(η5-C 5Me 5)M{(C 5H4N) 2C=NR)}Cl]PF 6 were prepared by the reaction of [MCl 2(η5-C 5Me 5)] 2(M = Ir or Rh) with dipyridyl-N-alkylimine ligands, (C 5H4N) 2C=NR (R = Me or Et) in the presence of NH 4PF6 at room temperature. The reaction also produced an unexpected dipyridyl-NH-ketimine organometallic compound [(η5-C 5Me 5)M {(C 5H4N) 2C=NH}Cl]PF 6 as minor product when the reaction was performed under refluxing acetonitrile. The NH-ketimine compounds were formed via N-C single bond cleavage of imine ligand resulting in coordination of the transformed ligand, (C 5H4N) 2C=NH to the metal centre. Complexes were obtained as their hexafluorophosphate salts and characterized based on IR, NMR and ESI-MS spectroscopic data. Authenticity of NH-ketimine organometallic compound was established by single crystal X-ray analysis of a representative compound, which crystallized in orthorhombic space group Pbcn and has a pseudo-octahedral geometry around the metal ion.