Nickel(II), Palladium(II) and Rhodium(I) Complexes of New NHC‐Thioether Ligands: Efficient Ketone Hydrosilylation Catalysis by a Cationic Rh Complex

Five new, bifunctional imidazolium–thioether ligands of the general formula RS(CH2)n(imidazolium)+ArBr– (n = 2 or 3, R = Et or tBu, Ar = 2,4,6‐trimethylphenyl or 2,6‐diisopropylphenyl) have been synthesised in good overall yields by a general method and used as N‐heterocyclic carbene precursors for complexation studies on various transition metals (NiII, PdII and RhI). Sulfur does not coordinate the nickel centre, whereas the two functional groups bind the palladium centre to form a dinuclear compound. Cationic rhodium(I) complexes have also been prepared and preliminary catalytic tests show that they have good activity for the hydrosilylation of ketones. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)