Ruthenium(II) complexes with 2,6-pyridyl-diimine ligands:: synthesis, characterization and catalytic activity in epoxidation reactions

Reaction of [RuCl2(p-cymene)](2) with the tridentate N-N'-N ligands, 2,6-pyridyl-diimines, led to substitution of p-cymene. The resulting complexes, believed to be coordinatively unsaturated, exhibit efficient activity for the epoxidation of cyclohexene in the presence of iodosobenzene (PhIO): the complexes formed initially take up donor molecules such as acetonitrile to achieve hexacoordination. The molecular structure for one of these, (acetonitrile){2,6-bis[1-(4-methoxyphenylimino)ethyl]pyridine}dichlororuthenium(II), 2, has been determined by X-ray diffraction. The immediate coordination sphere is a distorted octahedron with trans chloride atoms and a short Ru-N(py) (1.906 Angstrom) bond. (C) 1999 Elsevier Science B.V. All rights reserved.