Syntheses and structures of novel zerovalent 2,2′-bipyridyl or 1,10-phenanthroline ruthenium complexes

Rut 1-6-eta-cyclooctatriene)(eta(2)-dimethyl fumarate)(2) (2), which is easily derived from Ru(1-2:5-6-eta-cyclooctadiene)( 1-6-eta-cyclooctatriene) (1), reacts with bidentate nitrogen ligands, 2,2'-bipyridyl or 1,10-phenanthroline, to give novel ruthenium(0) complexes, Ru(1-2:5-6-eta-cyclooctatriene)(eta(2)-dimethyl fumarate)(N N)(N N = 2,2'-bipyridyl (3a) or 1,10-phenanthroline (3b)) quantitatively. On the other hand, the complex 1 reacts with dimethyl fumarate in the presence of N N to give novel ruthenium(0) complexes, Ru(1-2:5-6-eta-cyclooctadiene)(eta(2)-dimethyl fumarate)(N N) (N N = 2,2'-bipyridyl (4a) or 1,10-phenanthroline (4b)), in high yields. The structures of the complexes 3a, 3b, and 4b were established. by X-ray analyses, and the coordination geometry around the central ruthenium atom in these complexes was a distorted trigonal bipyramid. The two nitrogen atoms occupy an axial and an equatorial position, respectively, the two olefinic moieties of the cyclooctatriene or cyclooctadiene occupy an axial and an equatorial position, respectively, and the dimethyl fumarate was coordinated in the equatorial plane.