Synthesis and characterization of heterometallic M–Ru (M = Co, Rh, Ir) clusters containing the nido-dicarborane-1,2-dithiolato chelating ligand

Abstract

The 16-electron half-sandwich complexes Cp*M[S₂C₂(B₁₀H₁₀)] (M = Ir (1), Rh (2), Co (3)) react with [Ru(COD)Cl₂]_x under basic conditions at 35–40 °C to give different hetero-dinuclear clusters {Cp*M[S₂C₂(B₉H₁₀)]}Ru(COD) (M = Ir (1a), Rh (2a), Co (3a)) and {Cp*M[S₂C₂(B₉H₉)]}Ru(COD)(OCH₃) (M = Ir (1b), Rh (2b), Co (3b)) with open carborane cages. Moreover, B–H→Ru bridge bonds were observed in complexes 1a, 2a, 3a. In reaction a, minor products trinuclear complex {Cp*Ir[S₂C₂(B₁₀H₁₀)]}₂Ru (1c) and methoxyl-disubstituted complex Cp*Ir[S₂C₂(B₁₀H₈)(OCH₃)₂] (1d) were successfully isolated. However, when the reaction temperature decreased to 0–10 °C, the kinetically-controlled products, mono-substituted complex Cp*Ir[S₂C₂(B₁₀H₉)(OCH₃)] (1e) and disubstituted complex Cp*Ir[S₂C₂(B₁₀H₈)(OCH₃)₂] (1d), were isolated as the main products; nevertheless, the thermodynamically-controlled products, open-carborane complexes 1a and 1b, were isolated as the minor products. In complex Cp*Co[S₂C₂(B₉H₁₀)]Ru(C₇H₈) (3c), one COD coordinated to ruthenium has been replaced by toluene. The reactions demonstrate that different types of products can be obtained by controlling the reaction conditions. All these new complexes have been characterized by IR, ¹H NMR, ¹¹B NMR and elemental analyses. The molecular structures of 1a, 1b, 1c, 1d, 1e, 2a and 3a have also been determined by single-crystal X-ray diffraction analyses.