SYNTHESIS, CRYSTAL-STRUCTURES AND REACTIVITY OF RUTHENIUM-(II) AND RUTHENIUM-(III) COMPLEXES CONTAINING BETA-KETOPHOSPHINE OR PHOSPHINO ENOLATE LIGANDS

Reaction of 1, 2 or 3 equivalents of (diphenylphosphino)acetophenone, Ph(2)PCH(2)C(O)Ph(L), with [RUCl(2)(PPh(3))(2)] in toluene afforded selectively trans,mer-[RUCl(2){Ph(2)PCH(2)C(O)Ph}(PPh(3))(2)] 1, trans,cis,cis-[RUCl(2){Ph(2)PCH(2)C(O)Ph}(2)] 2 or trans,mer-[RuCl2{Ph(2)PCH(2)C(O)Ph}{Ph(2)PCH(2)C(O)Ph}(2)] 3. respectively. Complex 1 hydrogenates and isomerises hex-1-ene at atmospheric hydrogen pressure. whereas 2 is inactive. Complex 3 exhibits a dynamic behaviour on the H-1 NMR time-scale which corresponds to exchange between chelating and terminally bound phosphines. The activation energy of this process was calculated to be 63.7 +/- 0.7 kJ mol(-1). Reaction of 3 with TIPF6 in CH2Cl2 gave mer- [RuCl{Ph(2)PCH(2)C(O)Ph}(2){Ph(2)PCH(2)C(O)Ph}]PF6 9 Which reacted with a second equivalent of TIPF6 in MeCN to give the dicationic complex trans,cis,cis-[Ru{Ph(2)PCH(2)C(O) Ph}(2)(NCMe)(2)][PF6](2) 10. The fac and mer isomers of the tris(enolato) Ru-II complex [Na][RU{Ph(2)PCH - C(- O)Ph}(3)] 11a and 11b were obtained by reaction of 9 with NaH in tetrahydrofuran (thf). Treatment of 3 with NaOMe in toluene afforded selectively 11b, which has been crystallised by addition of 1,4.7,10,13-pentaoxacyclopentadecane (15-crown-5) to give [Na(15-crown-5). H2O][mer-RU{Ph(2)PCH - C(- O)Ph}(3)]. thf 12. Protonation of 11b with HBF4 . Et(2)O gave the neutral intermediate mer-[Ru{Ph(2)PCH - C(- O)Ph}(2){Ph(2)PCH(2)C(O)Ph}] 13, characterised spectroscopically, and the final product mer-[Ru{Ph(2)PCH(2)C(O)Ph(3)}][BF4](2) 14. Treatment of [RuCl3(AsPh(3))(2)(MeOH)] with 2 equivalents of L yielded the ruthenium(III) complex mer,trans-[RuCl3{Ph(2)PCH(2)C(O)Ph}{Ph(2)PCH(2)C(O)Ph}] 15, which was easily reduced to the ruthenium(II) complex 2. The solid state structures of complexes 2, 10 and 12 have been determined by single crystal X-ray analysis. The co-ordination of the metal in 2 and 10 is slightly distorted octahedral with the two phosphorous atoms (and oxygen atoms) in a cis position and the chloride and acetonitrile ligands, respectively, in a trans position. In the chiral anion of complex 12 the distorted octahedral structure has a meridional arrangement of the P atoms and electronic delocalisation occurs within the chelating phosphino enolate ligands.