184714-11-2Relevant academic research and scientific papers
Novel P-stereogenic PCP pincer-aryl ruthenium(II) complexes and their use in the asymmetric hydrogen transfer reaction of acetophenone
Medici, Serenella,Gagliardo, Marcella,Williams, Scott B.,Chase, Preston A.,Gladiali, Serafino,Lutz, Martin,Spek, Anthony L.,Van Klink, Gerard P.M.,Van Koten, Gerard
, p. 694 - 705 (2007/10/03)
Achiral P-donor pincer-aryl ruthenium complexes ([RuCl(PCP)(PPh 3)]) 4c,d were synthesized via transcyclometalation reactions by mixing equivalent amounts of [1,3-phenylenebis(methylene)] bis[diisopropylphosphine] (2c) or [1,3-phenylenebis(methylene)] bis[diphenylphosphine] (2d) and the N-donor pincer-aryl complex [RuCl{2,6-(Me2NCH2)2C6H 3}(PPh3)], (3; Scheme 2). The same synthetic procedure was successfully applied for the preparation of novel chiral P-donor pincer-aryl ruthenium complexes [RuCl(P*CP*)(PPh3)] 4a,b by reacting P-stereogenic pincer-arenes (S,S)-[1,3-phenylenebis(methylene)]bis[(alkyl) (phenyl)phosphines] 2a,b (alkyl = iPr or tBu, P*CHP*) and the complex [RuCl{2,6-(Me2NCH 2)2C6H3}(PPh3)], (3; Scheme 3). The crystal structures of achiral [RuCl(iPr,iPrPCP) (PPh3)] 4c and of chiral (S,S)-[RuCl-(tBu,PhPCP)(PPh 3)] 4a were determined by X-ray diffraction (Fig. 3). Achiral [RuCl(PCP)(PPh3)] complexes and chiral [RuCl(P*CP*) (PPh3)] complexes were tested as catalyst in the H-transfer reduction of acetophenone with propan-2-ol. With the chiral complexes, a modest enantioselectivity was obtained.
Complexes of bis-ortho-cyclometalated bisphosphinoaryl ruthenium(II) cations with neutral meta-bisphosphinoarene ligands containing an agostic C-H...Ru interaction
Dani,Toorneman,van Klink,van Koten
, p. 5287 - 5296 (2008/10/08)
The synthesis, characterization, and reactivity of various ruthenium(II) complexes [Ru-(R-PCP)(R′-PCHP)][OTf] are presented. These complexes are highly dissymmetric and show fluxional behavior in solution. They contain one monoanionic, η3-P,C,P′-tridentate-bonded bisphosphinoaryl ligand (R-PCP = [C6H2(CH2PPh2)2-2,6-R-4]-; R = H or Br) and one neutral, trans-P,P′-bidentate-bonded bisphosphinoarene ligand (R′-PCHP = C6H3(CH2PPh2)2-3,5-R′-1). The C-H bond that is ortho to both CH2PPh2 substituents of the bidentate-bonded ligand is interacting with the metal center (i.e., has an agostic contact with the cationic ruthenium center). The location of the agostic proton in the 1H NMR spectrum as well as the three-dimensional structure of these complexes in solution was obtained by means of several two-dimensional NMR techniques (1H-1H COSY, 31P-1H COSY, 13C-1H COSY, 1H NOESY, 1H ROESY, and 31P EXSY). The 1JHC of the agostic contact amounted to 112 Hz, which represents a reduction of 46 Hz in relation with the same coupling for this C-H bond in the free ligand. Furthermore, the molecular geometry of [Ru(H-PCP)(PCHP)][OTf] in the solid state was established by single-crystal X-ray diffraction techniques, and the structural features corroborate with the observations in solution. In the complex [Ru(H-PCP)(Br-PCHP)][OTf], interconversion of the cyclometalated and neutral bisphosphine ligands via exchange of the agostic hydrogen atom from the neutral to the cyclometalated carbon to yield [Ru(Br-PCP)(H-PCHP)][OTf] was observed. A mechanistic proposal based on an aromatic electrophilic substitution is discussed. Moreover, the reaction of [Ru(OSO2-CF3)(NCN)(PPh3)] (NCN = [C6H3(CH2NMe2)2-2,6]-) with the neutral bisphosphinoarene resulted in the quantitative formation of the new cyclometalated species [Ru(R-PCP)(R-PCHP)][OTf] with the net loss of the neutral bisaminoarene ligand NCHN and PPh3.
Five- and six-coordinate ruthenium complexes with the tridentate orthometallated aryl bisphosphine ligand [2,6-(Ph2PCH2)2C6H3]-
Jia, Guochen,Lee, Hon Man,Williams, Ian D.
, p. 173 - 180 (2007/10/03)
A series of ruthenium complexes with the orthometallated ligand [2,6-(Ph2PCH2)2C6H3]- (PCP) was synthesized. Reaction of RuCl2(PPh3)3 with 1,3-(Ph2PCH2)2C6H4 produced the coordinatively unsaturated complex RuCl(PPh3)(PCP), which was characterized by X-ray crystallography. Treatment of RuCl(PPh3)(PCP) with 4-phenylpyridine (pyph) yielded RuCl(pyph)(PPh3)(PCP). Treatment of RuCl(PPh3)(PCP) with PMe3 and CO generated RuCl(PMe3)2(PCP) and RuCl(CO)2(PCP) respectively. Reactions of RuCl(PPh3)(PCP) with NaH in THF and NaBH4 in methanol gave RuH(PPh3)(PCP) and RuH(CO)(PPh3)(PCP) respectively. The hydride complex RuH(PMe3)2(PCP) was prepared by the reaction of RuCl(PMe3)2(PCP) with NaBH4.
New arylruthenium(II) complexes of the P,C,P′-coordinating terdentate monoanionic aryl ligands [C6H2(CH2PPh 2)2-2,6-R-4]- (PCP-R-4; R = Ph, H).
Karlen, Thomas,Dani, Paulo,Grove, David M.,Steenwinkel, Pablo,Van Koten, Gerard
, p. 5687 - 5694 (2008/10/09)
The synthesis and characterization of new, five-coordinate, diamagnetic, 16-electron arylruthenium(II) complexes [RuIIX{C6H2(CH2PPh2) 2-2,6-R-4}(PPh3)] (1, X = Cl, R = H; 2, X = Cl, R = Ph; 3, X = OSO2CF3, R = H; 4, X = I, R = H) are described. These coordinatively unsaturated complexes contain a stable Caryl-Ru σ-bond resulting from pseudomeridional terdentate P,C,P′-bonding of the monoanionic {C6H2(CH2PPh2) 2-2,6-R-4}- ligand (general abbreviation PCP-R-4; for R = H and R = Ph, abbreviated as PCP and PCP-Ph, respectively) that also provides two P → Ru bonds. This bonding mode of the PCP-R-4 ligands adopted in complexes 1-4 means that these species are structurally closely related to the complexes [RuCl{C6H2(CH2NMe 2)2-2,6-R-4}(PPh3)] (R = H, Ph) in which there is terdentate N,C,N′-coordination. Complexes 1 and 2 were synthesized via cyclometalation reactions of the respective neutral diphosphine compounds C6H3(CH2PPh2)2-2,6-R-4 (general abbreviation PC(H)P-R-4; for R = H and R = Ph, abbreviated as PC(H)P and PC(H)P-Ph, respectively) with [RuIICl2(PPh3)4]. The complex [RuII(OTf)(PCP)(PPh3)], 3, prepared by reaction of 1 with AgOTf (OTf = OSO2CF3 = triflate), has the triflate anion bound to ruthenium in noncoordinating solvents. On the NMR time scale complex 3 in solution exhibits temperature-dependent fluxionality that is associated with reversible changes of the complex stereochemistry. The triflate PCP complex 3 reacts cleanly with the neutral N-donor ligand 2,2′:6′,2″-terpyridine (terpy) to afford [RuII(PCP)(terpy)][OTf], 5. However, whereas the reaction of terpy with the PCP-Ph complex 2 affords [RuII(PCP-Ph)(terpy)]Cl, 6, its reaction with PCP chloro complex 1 generates a mixture of products. These reactivities of PCP and PCP-Ph complexes (1-3) toward terpy are compared and contrasted with those of related ruthenium complexes containing the monoanionic aryldiamine ligand {C6H2(CH2NMe2) 2-2,6-R-4}- (abbreviated as NCN-R-4).
Coupling reactions of terminal acetylenes with a cyclometalated aryl ligand
Jia, Guochen,Lee, Hon Man,Xia, Hai Ping,Williams, Ian D.
, p. 5453 - 5455 (2008/10/09)
Reaction of RuCl2(PPh3)3 with 1,3-(PPh2-CH2)2C6H4 in refluxing 2-propanol produced RuCl(PPh3)(PCP) (PCP = 2,6-(PPh2CH2)2C6H3). Reaction of RuCl(PPh3)(PCP) with PhC≡CH gave the unusual coupling product RuCl(PPh3){η4-CHPh=C-2,6-(PPh2CH 2)2C6H3}, which has been characterized by X-ray diffraction. Coupling also occurred between RuCl-(PPh3)(PCP) and HC≡CC(OH)(Ph)CH3 to give RuCl-(PPh3){η4-CH2=CPhCH=C-2,6-(PPh 2CH2)2C6H3}.
