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

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(NH2tBu)Cl2] afforded [Cp*Ir(SnCl3)2{SnCl2(H2O)2}] (1) and [Cp*Ir(SnCl3)3][NH3tBu] (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(PPh3)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.