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 [( η 5 -C 5 Me 5 )M{(C 5 H 4 N) 2 C =NR)}Cl]PF 6 were prepared by the reaction of [MCl 2 ( η 5 -C 5 Me 5 )] 2 (M = Ir or Rh) with dipyridyl-N-alkylimine ligands, (C 5 H 4 N) 2 C =NR (R = Me or Et) in the presence of NH 4 PF 6 at room temperature. The reaction also produced an unexpected dipyridyl-NH-ketimine organometallic compound [( η 5 -C 5 Me 5 )M {(C 5 H 4 N) 2 C =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 5 H 4 N) 2 C =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. Graphical Abstract Pentamethylcyclopentadienyl iridium(III) and rhodium(III) complexes containing dipyridyl-N-alkylimine and dipyridyl-NH-ketimine ligands of formulation [( η 5 -C 5 Me 5 )M{(C 5 H 4 N) 2 C=NR}Cl]PF 6 and [( η 5 -C 5 Me 5 )M{(C 5 H 4 N) 2 C=NH}Cl]PF 6 were synthesized and characterized on the basis of spectroscopic data. Solid state structure of one representative NH-ketimine compound [6]PF 6 has been determined by X-ray crystallography