- Synthesis, structural characterization and catalytic activity of indenyl complexes of ruthenium bearing fluorinated phosphine ligands
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The synthesis, characterization and catalytic activity of new ruthenium complexes of fluorinated triarylphosphines is described. The new ruthenium complexes [RuCl(ind)(PPh3){P(p-C6H4CF3)3}] and [RuCl(ind)(PPh3){P(3,5-C6H3(CF3)2)3}] were synthesized in 57% and 24% isolated yield, respectively, by thermal ligand exchange of [RuCl(ind)(PPh3)2], where ind = indenyl ligand η5-C9H7?. The electronic and steric properties of the new complexes were studied through analysis of the X-ray structures and through cyclic voltammetry. The new complexes [RuCl(ind)(PPh3){P(p-C6H4CF3)3}] and [RuCl(ind)(PPh3){P(3,5-C6H3(CF3)2)3}] and the known complex [RuCl(ind)(PPh3)2}] differed only slightly in their steric properties, as seen from comparison of bond lengths and angles associated with the ruthenium center. As determined by cyclic voltammetry, the redox potentials of [RuCl(ind)(PPh3){P(p-C6H4CF3)3}] and [RuCl(ind)(PPh3){P(3,5-C6H3(CF3)2)3}] are +0.173 and + 0.370 V vs. Cp2Fe0/+, respectively, which are substantially higher than that of [RuCl(ind)(PPh3)2] (?0.023 V). After activation through chloride abstraction, the new complexes are catalytically active in the etherification of propargylic alcohols (8–24 h at 90 °C in toluene, 1–2 mol% catalyst loading, 29–61% isolated yields). As demonstrated by a comparative study for a test reaction, the three precursor complexes [RuCl(ind)(PPh3){P(p-C6H4CF3)3}], [RuCl(ind)(PPh3){P(3,5-C6H3(CF3)2)3}] and [RuCl(ind)(PPh3)2}] differed only slightly in catalytic activity.
- Stark, Matthew J.,Shaw, Michael J.,Fadamin, Arghavan,Rath, Nigam P.,Bauer, Eike B.
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- Reactivity studies of η5- indenyl and η5- Cp* ruthenium(II) complexes towards some polypyridyl ligands
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The reaction of [(η5-L3)Ru(PPh3) 2Cl], where; L3 = C9H7 (1), C 5Me5 (Cp*) (2) with acetonitrile in the presence of [NH4][PF6] yielded
- Singh, Keisham Sarjit,Mozharivskyj, Yurij A.,Kollipara, Mohan Rao
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p. 172 - 179
(2008/10/09)
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- New mononuclear ruthenium complexes of η5-cyclichydrocarbon containing azine ligands: Syntheses, spectral and structural studies
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A series of mononuclear indenyl and pentamethylcyclopentadienyl ruthenium(II) complexes of formulation [(η5-L3) Ru(PPh3)(L2)]X, (where L3 = indenyl, pentamethylcyclopentadienyl; X = PF6 or BF4 and L 2 = azine ligands) have been prepared by the reaction of [(η5-L3)Ru(PPh3)2(CH 3CN)]X with the appropriate azine ligands in methanol or dichloromethane/benzene mixture. The reaction of nitro substituted azine ligands with the complexes [(η5-L3)Ru(PPh3) 2(CH3CN)]X are solvent dependent. All these complexes were isolated as their PF6 or BF4 salts. The complexes were fully characterized with the help of microanalyses, FT-IR and NMR spectroscopy. The molecular structure of representative complexes 5c and 6a were established by single X-ray crystallography.
- Singh, Keisham Sarjit,Mozharivskyj, Yurij A.,Th?ne, Carsten,Kollipara, Mohan Rao
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p. 3720 - 3729
(2007/10/03)
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- Reactions of [(Ar)Ru(PPh3)2(CH3CN)]X (Ar=Cp*, η5-C5Me5 and indenyl, η5-C9H7; X-PF6 o BF 4) with terpyridines: Hypodentate nature of terpyridines (phterpy, pyterpy and diterpy)
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Ligand displacement reactions of the complexes of the type(Ar)Ru(PPh 3)2(CH3CN)]PF6 {Ar=Cp* (1) and indenyl (2)} have been investigated with N3-terpyridine ligands, 4′-phenyl-2,2′:6′,2″ terpyridine (phterpy), 4′-(4?-pyridyl)-2,2′:6′,2″ terpyridine (pyterpy) and 1,4-bis(2,2′:6,6″ terpyridin-4-yl) benzene (diterpy). The complexes [(Ar)Ru(PPh3)2(CH3CN)]PF6 {Ar=Cp* (1) and indenyl (2)} are reacted with these ligands to form stable complexes of the type [Cp*Ru(PPh3)(phterpy)]BF 4 (3), [Cp*Ru(PPh3)(pyterpy)]BF4 (4), [(η5ind)Ru(PPh3)(phterpy)]PF6 (5), [(η5ind)Ru(PPh3)(pyterpy)]PF6 (6), [(Cp*Ru(PPh3)}2 (diterpy)](BF4) 2 (7) and [(η5ind)Ru(PPh3)} 2(diterpy)l(PF6)2 (8) where respective ligands are coordinated in a bidentate fashion. When these reactions are carried out with chloro analogues [Cp*Ru(PPh3)2Cl] (9) and [(η5-ind)Ru(PPh3)2Cl] (10) with respective ligands viz. phterpy and pyterpy, a mixture of products are isolated including the complex type 3-6 and [RuCl(PPh3)2(N 3-phterpy)]PF6 (11) and [RuCl(PPh3) 2(N3-pyterpy)]PF6 (12) respectively. All these complexes have been characterized by spectral and analytical data.
- Rymmai,Rao, K. Mohan
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p. 1892 - 1895
(2007/10/03)
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- Synthesis and characterization of [(Cp*)Ru(PPh3)(N-base)]X and [(η5-C9H7)Ru(PPh3)(N-base)]X complexes (see abstract)
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The reactions of [(η5-Cp*)Ru(PPh3)2 (CH3CN)]X (1) and [(η5-indenyl)Ru(PPh3)2 (CH3CN)]X (2) (η5-Cp* = η5-C5Me5; η5- indenyl = η5-C9H7; X = BF4 or PF6) with 2,2′-bipyridine (bipy.) and 1,10-phenanthroline (phen.) in benzene or toluene yielded complexes of the type [(η5-Cp*)Ru(PPh3)(L2)]X where L2 = bipy, X=BF4 (3) and L2=phen, X=PF6 (4); [(η5-indenyl)Ru(PPh3)2(L2)]X where L2 = bipy, X = PF6 (5) and L2 = phen, X = PF6 (6). Complex 6 has been established by single crystal X-ray diffraction analysis. Complex 6 crystallizes in the monoclinic space group P 21/c, with a = 14.6020 (12), b = 12.7100 (17) and c = 18.981 (2) A?, β = 98.982 (9)°, V = 3479.5 (7) A?3 and Z = 4. These complexes can also be prepared from reactions of [(η5- Cp*)Ru(PPh3)2Cl] (7) and [(η5-indenyl)Ru(PPh3)2Cl] (8) with the corresponding ligands in the presence of NH4PF6 or NH4BF4 in toluene. All the complexes were characterized by spectral and analytical data.
- Rao, Kollipara Mohan,Rymmai, Evergreen K.
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p. 307 - 312
(2008/10/08)
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- Unusual activation of 1-ethynyl-1-cyclohexanol by [RuCl(η5-C9H7)-(PPh3) 2]: Synthesis and reactivity of the allenylidene derivative [Ru{=C=C=C(C13H20)}(η5-C9H 7)(PPh3)2][PF6]
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The reaction of [RuCl(η5-C9H7)(PPh3) 2] with an excess of 1-ethynyl-1-cyclohexanol and NaPF6 in refluxing methanol yielded the allenylidene complex [Ru{=C=C=C(C13H20)}(η5-C9H 7)(PPh3)2][PF6] 1 via an unprecedented coupling of two molecules of the propargyl (prop-2-ynyl) alcohol derivative. Complex 1 can also be obtained by reaction of the vinylvinylidene derivative [Ru{=C=C(H)R}(η5-C9H7)(PPh 3)2][PF6] 2 (R = 1-cyclohexenyl) with 1-ethynyl-1-cyclohexanol or 1-ethynylcyclohexene in refluxing methanol. The behaviour of 2 towards other 1-alkyn-3-ols has been studied but only the replacement of the vinylidene moiety by the propargyl alcohols, via an η1-vinylidene-η2-alkyne tautomerization process, to generate both vinylvinylidene [Ru{=C=C(H)R}(η5-C9H7)(PPh 3)2][PF6] (R = 1-cyclopentenyl, 1-cycloheptenyl or 1-cyclooctenyl) or allenylidene [Ru(=C=C=CR2)(η5-C9H7)(PPh 3)2][PF6] (R = Ph or R2=2,2′-biphenyldiyl) complexes along with 1-ethynylcyclohexene was observed. A similar 1,3-enyne elimination also takes place in the reaction of 2 with phenylacetylene or acetonitrile to afford [Ru{=C=C(H)Ph}(η5-C9H7)(PPh 3)2][PF6] and [Ru(N≡CMe)(η5-C9H7)(PPh 3)2][PF6], respectively. On the basis of these observations a mechanism for the formation of 1 is proposed. The allenylidene complex 1 regioselectively reacts with NaR, in THF at -20°C, to yield the neutral σ-alkynyl derivatives [Ru{C≡CC(C13H20)R}(η5-C 9H7)(PPh3)2] (R = C≡N or OMe). Protonation of the R = CN derivative with HBF4·Et2O, in diethyl ether at -20°C, afforded the cationic vinylidene complex [Ru{=C=C(H)C(C13H20)C≡N}(η5-C 9H7)(PPh3)2][BF4]. In contrast, protonation with R = OMe gives back the starting allenylidene derivative 1. The Royal Society of Chemistry 1999.
- Cadierno, Victorio,Gamasa, M. Pilar,Gimeno, Jose,Lastra, Elena
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p. 3235 - 3243
(2007/10/03)
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- A novel route to functionalized terminal alkynes through η1-vinylidene to η2-alkyne tautomerizations in indenyl-ruthenium(II) monosubstituted vinylidene complexes: Synthetic and theoretical studies
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Heating under reflux solutions of the monosubstituted vinylidene complex [Ru{=C=C(H)-Ph}(η5-C9H7)(PPh 3)2][PF6] (1) in nitriles yields the complexes [Ru(N≡CR)(η5-C9H7)(PPh 3)2]-[PF6] (R = Me (2a), Et (2b), Ph (2c)) and phenylacetylene. The process proceeds via an initial η1-vinylidene-η2-alkyne tautomerization followed by the displacement of the coordinated π-alkyne by the solvent. Vinylidene complexes [Ru{=C=C(H)R}(η5-C9H7)(PPh 3)2][PF6] (R = (η5-C5H4)Fe(η5-C 5H5) (3), 4-NO2-C6H4 (4)) also react with acetonitrile to yield the nitrile derivative 2a and the corresponding terminal alkynes HC≡CR. Cationic alkenyl-vinylidene derivatives [RU{=C=C(H)CH=CR1R2}(η5-C9H 7)(PPh3)2][BF4] (R1 = R2 = Ph (7a), R1 = H; R2 = 4-OMe-C6H4 [(Z)-Tb], 4-NO2-C6H4 [(E,Z)-7c], (η5-C6H4)Fe(η5-C 5H5) [(E)-7d]) behave similarly. Thus, the treatment of 7a-d with acetonitrile at reflux results in the formation of complex 2a and the liberation of the corresponding terminal 1,3-enyne HC≡CCH=CR1R2 (8a-d). The formation of the enynes 8b-d is stereoselective, giving rise to the E stereoisomer. The allenylidene complex [Ru{=-C=C-C(C13H20)}(η5-C9H 7)(PPh3)2][PF6] (9), containing the bicyclic [3.3.1]non-2-en-9-ylidene moiety C13H20, reacts with NaC≡CH in THF at -20°C to yield the neutral σ-alkynyl derivative [Ru{C≡CC(C≡CH)C13H20}(η5-C 9H7)(PPh3)2] (10) in a regioselective manner. Protonation of 10 with HBF4·Et2O, in diethyl ether at -20°C, affords the vinylidene complex [Ru{=C=C(H)C(C≡CH)C13H20}(η5-C 9H7)(PPh3)2][BF4] (11), which can be easily demetalated by heating in refluxing acetonitrile to give 2a and the unprecedented diyne (HC≡C)2CC13H20 (12). These demetalation processes allow the quantitative recovery of the metal auxiliary as the labile complex 2a, which can be used as starting material for further reactions. Ab initio molecular orbital calculations on the η1-vinylidene to η2-alkyne tautomerization have been performed. It is shown that the process proceeds through a 1,2-[H] shift mechanism showing that the conversion requires an energy barrier of 29.9 kcal/ mol. This is a value low enough to be overcome under the experimental reaction conditions allowing the formation of the labile η2-alkyne complex and the subsequent exchange of the coordinated alkyne by acetonitrile.
- Cadierno, Victorio,Gamasa, M. Pilar,Gimeno, José,Pérez-Carre?o, Enrique,García-Granda, Santiago
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p. 2821 - 2832
(2008/10/08)
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