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 eas ily 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-phenanth roline, to give novel ruthenium(0) complexes, Ru(1-2:5-6-eta-cyclooctatrien e)(eta(2)-dimethyl fumarate)(N N)(N N = 2,2'-bipyridyl (3a) or 1,10-phenant hroline (3b)) quantitatively. On the other hand, the complex 1 reacts with dimethyl fumarate in the presence of N N to give novel ruthenium(0) complex es, 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 structu res of the complexes 3a, 3b, and 4b were established. by X-ray analyses, an d the coordination geometry around the central ruthenium atom in these comp lexes was a distorted trigonal bipyramid. The two nitrogen atoms occupy an axial and an equatorial position, respectively, the two olefinic moieties o f the cyclooctatriene or cyclooctadiene occupy an axial and an equatorial p osition, respectively, and the dimethyl fumarate was coordinated in the equ atorial plane.