| A group of ruthenium(II) complexes possessing chelating diphosphine ligands (P-P) was prepared, and their reactivity was studied. The diphosphines employed were DPPB (1,4-bis(diphenylphosphino)butane), (R)-BINAP (( R)-2,2′-bis(diphenylphosphino)-1,1′ -binaphthyl), and (S,S)-DIOP ((S,S)-2,3- O-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane), which form seven-membered chelate rings.*; Most work involved the characterization and chemistry of Ru(II)(P-P) complexes containing ancillary N-donor ligands. The complexes are readily prepared from RuCl2(P-P)(PPh3) (P-P = DPPB or ( R)-BINAP) and heterocyclic, pyridyl-based ligands (monodentate L, and bidentate L2). With the monodentate L ligands, the trans-RuCl2((R)-BINAP)(L)2 complexes are formed, while for the bidentate L2 ligands, isomerization of trans- to cis-RuCl2(( R)-BINAP)(L2) occurs, via both photochemical and thermal processes. Cis-RuX2((R)-BINAP)(L 2) (X = Br, I; L2 = bipy, phen) were prepared by halide metathesis from the corresponding dichloro species. Restricted rotation of the pyridyl rings in the trans-RuCl2((R)-BINAP)(L) 2 species, and of the phenyl rings in all the trans-RuCl 2((R)-BINAP)(L)2 and cis-RuX 2((R)-BINAP)(L2) complexes, was detected by variable temperature NMR spectroscopy. X-ray crystallographic determinations of the structures of trans-RuCl2((R)-BINAP)(py) 2, cis-RuCl2((R)-BINAP))(phen), cis-RuCl2((R)-BINAP))(bpa), and cis-RuBr2((R)-BINAP))(bipy) show the presence of arene-stacking interactions involving the binaphthyl backbone of BINAP, as well as phenyl and pyridyl rings. The arene-stacking is proposed to result in the restricted rotations observed spectroscopically in solution. Unusual temperature- and solvent-dependent 31P{lcub}1H{rcub} NMR spectroscopic behaviour was observed for most of the cis-RuX 2((R)-BINAP)(L2) complexes, in which unexpected degeneracy of the two 31P signals occurs at specific solvent and temperature combinations which differ for each complex. Reaction of the RuCl2(P-P)(L2) complexes with H2 in the presence of base gives Ru(H)Cl(P-P)(L2) species, while reaction with CO gives [RuCl(CO)(P-P)(L2)]Cl, these species being characterized in situ by NMR spectroscopy. Cationic, solvento complexes of type [RuCl(P-P)(L2)(RCN)]PF6 (where R = Me, Ph) and [Ru(P-P)(L 2)(H2O)(OTf)]OTf (OTf = CF3SO3 −) were prepared from RuCl2(P-P)(L2), and characterized, including structural determinations of cis-[RuCl(DPPB)(bipy)(MeCN)]PF 6 and cis-[Ru(DPPB)(phen)(H2O)(OTf)]OTf.; Several of the complexes mentioned above were tested for catalytic activity in the homogeneous hydrogenation of the aldimines PhC(H)=NCH2Ph and PhC(H)=NPh, and preliminary results are presented.; The aerial oxidation of one P-atom of the diphosphine in RuCl2(P-P)(L 2) was discovered serendipitously, and synthetic routes to bis(phosphine) monooxide (BPMO) complexes from |
