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-py ridyl-diimines, led to substitution of p-cymene. The resulting complexes, b elieved to be coordinatively unsaturated, exhibit efficient activity for th e epoxidation of cyclohexene in the presence of iodosobenzene (PhIO): the c omplexes formed initially take up donor molecules such as acetonitrile to a chieve hexacoordination. The molecular structure for one of these, (acetoni trile){2,6-bis[1-(4-methoxyphenylimino)ethyl]pyridine}dichlororuthenium(II) , 2, has been determined by X-ray diffraction. The immediate coordination s phere 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 reserv ed.