SnCl2 insertion into Ir-Cl and Rh-Cl bonds: Synthesis, characterization and catalytic activity of three-legged piano-stool trichlorostannyl iridium and rhodium complexes

Article abstract of DOI:10.1016/j.jorganchem.2014.06.011

Facile insertion reaction of SnCl₂ across pentamethylcyclopentadienyl complexes of Ir(III) and Rh(III) resulted in the formation of Ir-SnCl₃ and Rh-SnCl₃ heterobimetallic complexes. Treatment of SnCl₂ with [Cp*IrCl₂] ₂ and [Cp*Ir(NH₂^tBu)Cl₂] afforded [Cp*Ir(SnCl₃)₂{SnCl₂(H ₂O)₂}] (1) and [Cp*Ir(SnCl₃) ₃][NH₃^tBu] (3), respectively. Similarities in NMR data for complexes 1 and 3 suggested that complex 1 converts to anionic [Cp*Ir(SnCl₃)₃] species in solution via rapid chloride exchange. Similarly, insertion reaction of SnCl₂ with [Cp*Ir(PPh₃)Cl₂] and [Cp*Rh(PPh ₃)Cl₂] afforded single insertion complex [Cp*Ir(PPh₃)(SnCl₃)Cl] (2) and double insertion complex [Cp*Rh(PPh₃)(SnCl₃)₂] (4), respectively. All these new complexes were characterized by multinuclear NMR spectroscopy, while complexes 1, 3 and 4 were structurally characterized by single crystal X-ray diffraction technique. Complexes 1-4 were also tested as catalyst for bisarylation of aldehyde with arene and it was observed that only complexes 1 and 3 were active. Scope of this organic reaction was examined for different arenes and heteroarenes and in all the cases very good yields of triarylmethane derivatives were achieved.