Syntheses and structures of novel zerovalent ruthenium monodentate amine complexes

Novel ruthenium(0) monodentate amine (primary, secondary, and tertiary) and pyridine complexes, [Ru(eta(6)-cot)(eta(2)-dmfm)(L)] (cot=cycloocta-1,3,5- triene, dmfm=dimethyl fumarate; L=propylamine, benzylamine, dimethylamine, morpholine or pyridine), were prepared by the reaction of [Ru(eta(6)-cot)(e ta(2)-dmfm)(2)] with the corresponding amine in high yields. The structures of three of the complexes were determined by X-ray analyses and the co-ord ination geometry around the central ruthenium atom is a highly distorted tr igonal bipyramid. The nitrogen atom and one carbon-carbon double bond of th e cyclooctatriene occupy the two axial positions, and the other two olefini c bonds of the cyclooctatriene and dimethyl fumarate the equatorial positio ns. The propylamine complex is in equilibrium with [Ru(eta(4)-cot)(eta(2)-d mfm)(PrNH2)(2)] in the presence of an excess of propylamine. The structure of this complex was confirmed by X-ray analysis. The position of the second amine is equatorial and the cyclooctatriene co-ordinated in a 1-2:5-6-eta bonding mode. When it was dissolved in CD2Cl2, propylamine at the equatoria l position was dissociated, changing the eta(4)-cyclooctatriene to the eta( 6) mode to give [Ru(eta(6)-cot)(eta(2)-dmfm)(PrNH2)].