Crystal structure of 1,5-cyclooctadiene-bis[(4-methyl-pyridin-2-yl)- trimethyIsilanyl-amido]ruthenium(II), RU( C8H12 )(C9H15N2Si)2

Abstract

Source of materialTo a stirred solution of 0.4 g (2.2 mmol) of lithiated (4-methylpyridin-2-yl)-trimethylsilanyl-amine in 8 mL diethyl ether a suspension of 0.308 g (1.1 mmol) [(cod)RuCh] (cod = 1,5-cyclooctadiene) in 10 mL thf was added at -30 °C and the solution was stirred for six hours at this temperature. The reaction mixture was then stored at -25 °C over night. The solvent was removed in vacuum and the residue was extracted with hexane and filtered. The yellow-brown filtrate was stored at -25 °Cto afford yellow crystals suitable for X-ray crystal structure analysis (yield 0.38 g, 61 %). DiscussionThe development of amido metal chemistry of the early transition metals increased dramatically in the last decades. In comparison late transition amido metal chemistry is much less developed [1]. The amido-metal bond in the complexes can be stabilized by additional N-donor functions, for instance by a pyridine moiety [2].Recently, we have reported examples of amido complexes of late transition metals (nickel and palladium) stabilized by deprotonated 2-aminopyridines [3,4]. The first aminopyridinato complex of ruthenium, a dinuclear complex, was reported by Cotton et al.[5], The title compound, a mononuclear ruthenium complex, consists of two aminopyridinato ligands and one cod ligand. The bulky trimethylsilyl substituents at the amido Ν atoms force the aminopyridinato ligands into a transoid arrangement. An unusual binding situation is notified by the small chelating angles of 63.00° (Z.N1-Rul-N2) and of 63.10° (ZN3-Rul-N4). Both pyridine rings are in plane with the ruthenium atom and the appropriate amido Ν atoms. The deviations from the planes are 0.0047 Ä and 0.0141 A. The angle between these planes is 87.3°. For each of the two aminopyridinato ligands, the Ru-Npyndme distance (<*(Rul-N2) = 2.071 Ä, d{Rul-N4) = 2.082 Ä) is significantly shorter than the corresponding Ru-Namido distance (</(Rul-Nl) = 2.179 Ä, d(Rul-N3) = 2.173 Ä).