Cyclopentadienyl Ruthenium Research Articles

A Trinuclear Aqua Cyano‐Bridged Ruthenium Complex [{(η5‐C5H5)(PPh3)2Ru(μ‐CN)}2RuCl2(PPh3)(H2O)]PF6: Synthesis, Characterization and Crystal Structure

AbstractThe organometallic trinuclear aqua cyano‐bridged complex [{(η5‐C5H5)(PPh3)2Ru(μ‐CN)}2RuCl2(PPh3)(H2O)]PF6 (1), in which the fragment [RuCl2(PPh3)(H2O)] acts as a bridge and an acceptor group between the two terminal cyclopentadienyl ruthenium cyano moieties, was isolated in moderate yield from the reaction of [(η5‐C5H5)(PPh3)2RuCN] with [RuCl2(PPh3)3] in THF. To the best of our knowledge, compound 1 is one of the few examples of a trinuclear array of ruthenium fragments bridged by the nitrogen atom of the–C≡N– group (Ru–C≡N–Ru′–N≡C–Ru) with a Ru‐coordinated water molecule. The new aqua complex was structurally characterized by FTIR, 1H, 13C, and 31P NMR spectroscopy, mass spectrometry, elemental analysis, single‐crystal X‐ray diffraction, and cyclic voltammetry. The title complex crystallizes in a triclinic unit cell a = 17.3477(6) Å, b = 17.8551(5) Å, c = 18.2460(7) Å, α = 95.693(2)°, β = 111.648(2)°, and γ = 97.839(2)° in the space group P$\bar {1}$ with Z = 2.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Reactivity studies of cyclopentadienyl ruthenium(II), osmium(II) and pentamethylcyclopentadienyl iridium(III) complexes towards 2-(2′-pyridyl)imidazole derivatives

The reaction of [CpRu(PPh 3) 2Cl] and [CpOs(PPh 3) 2Br] with chelating 2-(2′-pyridyl)imidazole (N ∩ N) ligands and NH 4PF 6 yields cationic complexes of the type [CpM(N ∩ N)(PPh 3)] + ( 1: M = Ru, N ∩ N = 2-(2′-pyridyl)imidazole; 2: M = Ru, N ∩ N = 2-(2′-pyridyl)benzimidazole; 3: M = Ru, N ∩ N = 2-(2′-pyridyl)-4,5-dimethylimidazole; 4: M = Ru, N ∩ N = 2-(2′-pyridyl)-4,5-diphenylimidazole; 5: M = Os, N ∩ N = 2-(2′-pyridyl)imidazole; 6: M = Os, N ∩ N = 2-(2′-pyridyl)benzimidazole). They have been isolated and characterized as their hexafluorophosphate salts. Similarly, in the presence of NH 4PF 6, [Cp∗Ir(μ-Cl)Cl] 2 reacts in dry methanol with N ∩ N chelating ligands to afford in excellent yield [Cp∗Ir(N ∩ N)Cl]PF 6 ( 7: N ∩ N = 2-(2′-pyridyl)imidazole; 8: N ∩ N = 2-(2′-pyridyl)benzimidazole). All the compounds have been characterized by infrared and NMR spectroscopy and the molecular structure of [ 1]PF 6, [ 2]PF 6 and [ 7]PF 6 by single-crystal X-ray structure analysis.

Grafting of cyclopentadienyl ruthenium complexes on aminosilane linker modified mesoporous SBA-15 silicates

Cyclopentadienyl ruthenium phosphane and carbene complexes are grafted on the surface of mesoporous SBA-15 molecular sieves through an aminosilane linker. The nature of the support after the grafting is examined by powder XRD, TEM and N(2) adsorption/desorption analysis. Elemental analysis, FT-IR, DRIFTS, TG-MS and MAS-NMR studies confirm the successful grafting of the complexes on the surface. The grafted materials are applied for catalytic aldehyde olefination and cyclopropanation.

Regio‐ and Stereoselective Addition of Carboxylic Acids to Phenylacetylene Catalyzed by Cyclopentadienyl Ruthenium Complexes.

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Synthesis, Characterization, and DNA Binding of New Water-Soluble Cyclopentadienyl Ruthenium(II) Complexes Incorporating Phosphines

The new water-soluble ruthenium(II) chiral complexes [RuCpX(L)(L')](n+) (X = Cl, I. L = PPh3; L' = PTA, mPTA; L = L' = PTA, mPTA) (PTA = 1,3,5-triaza-7-phosphaadamantane; mPTA = N-methyl-1,3,5-triaza-7-phosphaadamantane) have been synthesized and characterized by NMR and IR spectroscopy and elemental analysis. The salt mPTA(OSO2CF3) was also prepared and fully characterized by spectroscopic techniques. X-ray crystal structures of [RuClCp(PPh3)(PTA)] (2), [RuCpI(PPh3)(PTA)] (3), and [RuCpI(mPTA)(PPh3)](OSO2CF3) (9) have been determined. The binding properties toward DNA of the new hydrosoluble complexes have been studied using the mobility shift assay. The ruthenium chloride complexes interact with DNA depending on the hydrosoluble phosphine bonded to the metal, while the corresponding compounds with iodide, [RuCpI(PTA)2] (1), [RuCpI(PPh3)(PTA)] (3), [RuCpI(mPTA)2](OSO2CF3)2 (6), and [RuCpI(mPTA)(PPh3)](OSO2CF3) (9), do not bind to DNA.

Regio- and stereoselective addition of carboxylic acids to phenylacetylene catalyzed by cyclopentadienyl ruthenium complexes

The direct addition of carboxylic acids to terminal alkynes such as phenylacetylene in the presence of catalytic amount of [CpRu(CO) 2Cl] ( 1) or [{CpRu(CO) 2} 2] ( 2) affords the anti-Markovnikov adducts with high selectivity. In most instances, the E-enol esters are the major products.

Diastereoselectivity at chiral metal center of half-sandwich-type ruthenium complexes with planar-chiral cyclopentadienyl ligands in multiple ligand transfer reaction

The triple ligand transfer reaction between planar-chiral cyclopentadienyl–ruthenium complexes [Cp′Ru(NCMe) 3][PF 6] ( 1) (Cp′ = 1-(COOR 2)-2-Me-4-R 1C 5H 2; R 1 = Me, Ph, t-Bu) and iron complexes CpFe(CO)(L)X ( 2) (L = PMe 3, PMe 2Ph, PMePh 2, PPh 3; X = I, Br) resulted in the formation of metal-centered chiral ruthenium complexes Cp′Ru(CO)(L)X ( 3) in moderate yields with diastereoselectivities of up to 68% de. The configurations of some major diastereomers were determined to be S Cp ∗ R Ru ∗ by X-ray crystallography. The diastereoselectivity of 3 was under kinetic control and not affected by the steric effect of the substituents on the Cp′ ring of 1 and the phosphine of 2. Although the double ligand transfer reaction between [Cp′Ru{P(OMe) 3}(NCMe) 2][PF 6] ( 7) and CpFe(CO) 2X ( 8) produced Cp′Ru{P(OMe) 3}(CO)X ( 9), the selectivity at the ruthenium center was low.

Combined Ruthenium(II) and Lipase Catalysis for Efficient Dynamic Kinetic Resolution of Secondary Alcohols. Insight into the Racemization Mechanism

Pentaphenylcyclopentadienyl ruthenium complexes (3) are excellent catalysts for the racemization of secondary alcohols at ambient temperature. The combination of this process with enzymatic resolution of the alcohols results in a highly efficient synthesis of enantiomerically pure acetates at room temperature with short reaction times for most substrates. This new reaction was applied to a wide range of functionalized alcohols including heteroaromatic alcohols, and for many of the latter, enantiopure acetates were efficiently prepared for the first time via dynamic kinetic resolution (DKR). Different substituted cyclopentadienyl ruthenium complexes were prepared and studied as catalysts for racemization of alcohols. Pentaaryl-substituted cyclopentadienyl complexes were found to be highly efficient catalysts for the racemization. Substitution of one of the aryl groups by an alkyl group considerably slows down the racemization process. A study of the racemization of (S)-1-phenylethanol catalyzed by ruthenium hydride eta(5)-Ph(5)CpRu(CO)(2)H (8) indicates that the racemization takes place within the coordination sphere of the ruthenium catalyst. This conclusion was supported by the lack of ketone exchange in the racemization of (S)-1-phenylethanol performed in the presence of p-tolyl methyl ketone (1 equiv), which gave <1% of 1-(p-tolyl)ethanol. The structures of ruthenium chloride and iodide complexes 3a and 3c and of ruthenium hydride complex 8 were confirmed by X-ray analysis.

Adducts of Cyclotriphosphorus Complexes with Cyclopentadienyl Ruthenium Fragments: Synthesis, Solid‐State Structure and Solution Behaviour

AbstractTreatment of the cyclo‐P3 complexes [(triphos)M(η3‐P3)]‐[triphos = 1,1,1‐tris(diphenylphosphanylmethyl)ethane; M = Co (1), Rh (2)] with stoichiometric amounts of [CpRu‐(CH3CN)2(PR3)]PF6 [R = Ph (3), Me (4), Cy (5)] in CH2Cl2 in the presence of CH3CN yields the bimetallic adducts [{(triphos)M}(μ,η3:1‐P3){CpRu(CH3CN)(PR3)}]PF6 [M = Co; R = Ph (6), Me (7), Cy (8); M = Rh; R = Ph, (9), Me (10), Cy (11)]. The rhodium derivatives 9 and 11, upon treatment with one equivalent of PMe3, form the complexes [{(triphos)Rh}(μ,η3:1‐P3){CpRu(PMe3)(PR3}]PF6 [R = Ph (12), Cy (13)]. On standing in CH2Cl2, the rhodium complexes 9 and 10 lose acetonitrile to yield compounds with the formula [{(triphos)Rh}(μ,η3:1,1'‐P3){CpRu(PR3)}]PF6 [R = Ph (14), Me (15)]. All the compounds have been characterised by elemental analyses and, in solution, by 31P and 1H NMR spectroscopy. The 31P{1H} EXSY NMR spectroscopic data at different temperatures of 11 and 14 have highlighted the occurrence of independent dynamic processes that exchange both the triphos and the cyclo‐P3 phosphorus nuclei. An X‐ray structural investigation carried out on 6 has confirmed the occurrence of the μ,η3:1‐ligating behaviour of the cyclo‐P3 ligand. (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2005)

Stereoselective ligand-exchange reaction of planar-chiral cyclopentadienyl-ruthenium complexes: thermodynamic control of configuration at a stereogenic metal center.

The reaction of planar-chiral cyclopentadienyl-ruthenium complexes with Bu4NI resulted in the formation of iodo complexes with high diastereoselectivity (up to >99%de). The stereochemistry of the ruthenium center in the starting material did not influence the diastereoselectivity of the products. Epimerization of a diastereomerically pure sample gave a mixture of two diastereomers in the same ratio as with the ligand-exchange reaction, suggesting that the selectivity is determined by the difference in thermodynamic stability between the diastereomeric pair of iodo complexes. The ratio of the products depends on the nature of the substituent on the cyclopentadienyl ring and P ligands on the ruthenium atom. A combination of small substituents on the cyclopentadienyl group and small P ligands with strong electron-donating ability favored the formation of 2-I. The bulkiness of the substituents on the cyclopentadienyl group or of the P ligands, and low electron-donating ability of the P ligands increased the ratio of 2-II complexes to 2-I isomer.

Dipodal ligands from chiral spiro[2.4]hepta-4,6-dienes: solid state conformational effects by tether substitution in dipodal η 5,η 1-CpP–ruthenium(II) complexes

New chiral spiro[2.4]hepta-4,6-dienes were prepared and used in an efficient synthesis of cyclopentadienyl ruthenium complexes with pendant phosphine donors. Solid state structures reveal a conformation trend among three structurally homologous complexes that involves subtle twisting about the tether with increasing substitution at the alpha carbon. These results suggest architectural requirements for future ligand designs.

Chelate Complexes of Functionalized Cycloheptatrienyl Ligands: Molybdenum Complexes with Linked Cycloheptatrienyl‐Phosphane Ligands and Their Use in Catalytic Carbon−Carbon Bond Formation

AbstractThe synthesis of P‐functionalized molybdenum chelate complexes incorporating the linked cycloheptatrienyl‐phosphane ligand [2‐(diisopropylphosphanyl)phenyl]cycloheptatrienyl (o‐iPr2P−C6H4−C7H6) is described. From the ligand precursor [2‐(cyclohepta‐2,4,6‐trienyl)phenyl]diisopropylphosphane (1) the paramagnetic 17‐electron dibromide [(o‐iPr2PC6H4‐η7‐C7H6)MoBr2(P−Mo)] (2) can readily be obtained. This is a versatile starting material for the preparation of cycloheptatrienyl molybdenum hydrides [(o‐iPr2PC6H4‐η7‐C7H6)Mo(η2‐BH4)(P−Mo)] (3) and [(o‐iPr2PC6H4‐η7‐C7H6)Mo(PPh3)H(P−Mo)] (4). Treatment of 3 with dimethylanilinium tetraphenylborate ([PhNMe2H][BPh4]) allows the production of the cationic 14‐electron complex fragment [(o‐iPr2PC6H4‐η7‐C7H6)Mo(P−Mo)]+ (13), which can be stabilized in the presence of suitable ligands L. The complexes [(o‐iPr2PC6H4‐η7‐C7H6)MoL2(P−Mo)]BPh4 [L = dimethylphenyl isocyanide, (5)BPh4; L2 = η4‐2,5‐norbornadiene, (6)BPh4; L2 = η2‐phenylacetylene, (7)BPh4; L2 = η2‐tert‐butylacetylene, (8)BPh4] can thus be isolated in good yields. The alkyne complex (7)BPh4 can be used as a single‐source catalyst for the oligomerization of phenylacetylene, affording a mixture of triphenylbenzenes and linear oligomers. Quantum chemical calculations reveal an intimate relationship between the catalytically active 14‐electron complex fragment [(o‐iPr2PC6H4‐η7‐C7H6)Mo(P−Mo)]+ (13) and hypothetical isoelectronic and isolobal complexes of the type [(o‐iPr2PC6H4‐η5‐C5H4)M(P−M)]+ (M = Ru, 14; M = Os, 15), indicating that cycloheptatrienyl molybdenum systems might in general be a suitable replacement for cyclopentadienyl ruthenium and osmium catalysts. (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2003)

Formation of Vinyl Halides via a Ruthenium‐Catalyzed Three‐Component Coupling.

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Formation of vinyl halides via a ruthenium-catalyzed three-component coupling.

The ruthenium-catalyzed three-component coupling of an alkyne, an enone, and halide ion to form E- or Z-vinyl halides has been investigated. Through systematic optimization experiments, the conditions effecting the olefin selectivity were examined. In general, more polar solvents such as DMF favored the formation of the E-isomer, and less polar solvents such as acetone favored formation of the Z-isomer. The optimized conditions for the formation of E-vinyl chlorides were found to be the use of cyclopentadienyl ruthenium (II) cyclooctadiene chloride, stannic chloride pentahydrate as a cocatalyst, and for a chloride source, either ammonium chloride in DMF/water mixtures or tetramethylammonium chloride in DMF. A range of several other ruthenium (II) catalysts was also shown to be effective. A wide variety of vinyl chlorides could be formed under these conditions. Substrates with tethered alcohols or ketones either five or six carbons from the alkyne portion gave instead diketone or cyclohexenone products. For formation of vinyl bromides, a catalyst system involving the use of cyclopentadienylruthenium (II) tris(acetonitrile) hexafluorophosphate with stannic bromide as a cocatalyst was found to be most effective. The use of ammonium bromide in DMF/acetone mixtures was optimal for the synthesis of E-vinyl bromides, and the use of lithium bromide in acetone was optimal for formation of the corresponding Z-isomer. Under either set of conditions, a wide range of vinyl bromides could be formed. When alkynes with propargylic substituents are used, enhanced selectivity for formation of the Z-isomer is observed. When aryl acetylenes are used as the coupling partners, complete selectivity for the Z-isomer is obtained. A mechanism involving a cis or trans halometalation is invoked to explain formation of the observed products. The vinyl halides have been shown to be precursors to alpha-hydroxy ketones and cyclopentenones, and as coupling partners in Suzuki-type reactions.

Half-sandwich cyclopentadienyl ruthenium complexes of achiral and chiral diphosphazanes

Reaction of [CpRu(PPh3)2Cl] (1) {Cp = η5-(C5H5)} with X2PN(CHMe2)PYY′ {X = Y = Y′ = Ph (L1); X = Y = Ph, Y′ = OC6H4Me-4 (L4); X = Y = Ph, Y′ = OC6H3Me2-3,5 (L5); X = Y = Ph, Y′ = N2C3HMe2 (L6)} yields the cationic chelate complexes, [CpRu(η2-(X2PN(CHMe2)PYY′))PPh3]Cl. On the other hand, the reaction of 1 with X2PN(CHMe2)PYY′ {X2 = YY′ = O2C6H4(L2)} gives the complex, [CpRu(η1-L2)2PPh3]Cl. Both types of complexes are formed with X2PN(CHMe2)PYY′ {X = Ph, YY′ = O2C6H4 (L3)}. The reaction of 1 with (R),(S)-(H12C20O2)PN(CHMe2)PPh2 (L7) yields both cationic and neutral complexes, [CpRu{η2-(L7)}PPh3]Cl and [CpRu{η1-(L7)}2PPh3]Cl and [CpRu{η2-(L7)}Cl]. The reactions of optically pure diphosphazane, Ph2PN(*CHMePh)PPhY (Y = Ph (L8); Y = N2C3HMe2-3,5 (L9)) with 1 give the neutral and cationic ruthenium complexes, [CpRu{η2-(Ph2PN(R)PPhY)}Cl] and [CpRu{η2-(Ph2PN(R)PPhY)}PPh3]Cl. “Chiral-at-metal” ruthenium complexes of diphosphazanes have been synthesized with high diastereoselectivity. The absolute configuration of a novel ruthenium complex, (SCSPRRu)-[(η5-C5H5)Ru*{η2-(Ph2PN(*CHMePh)P*Ph(N2C3HMe2-3,5))}Cl] possessing three chiral centers, is established by X-ray crystallography. The reactions of [CpRu{η2-(L8)}Cl] with mono or diphosphanes in the presence of NH4PF6 yield the cationic complexes, [CpRu{η2-(L8)}{η1-(P)}]PF6 {P = P(OMe)3, PPh3, Ph2P(CH2)nPPh2 (n = 1 or 2)}.

Control of Stereochemistry at the Metal Center in Planar-Chiral Cyclopentadienyl Ruthenium Complexes with Anchor Phosphine on Complexation with Salicylideneaminato Ligands

Reactions of planar-chiral cyclopentadienyl-phosphine ruthenium complexes [η5,η1-{C5H2(Me)(R)COO(CH2)2PPh2}Ru(MeCN)2][PF6] (1a, R = Me; 1b, R = Ph) with sodium salicylideneaminato (2) led to the fo...

Neutral carbene and vinylidene cyclopentadienyl ruthenium complexes with PPh2(2-MeC6H4)

Abstract The complex [RuCl(η 5 -C 5 H 5 ){PPh 2 (2-MeC 6 H 4 )} 2 ] ( 1 ), unlike the triphenylphosphine analog [RuCl(η 5 -C 5 H 5 )(PPh 3 ) 2 ], reacts under mild conditions with CO, N 2 CPh 2 and HCCPh to give the neutral carbonyl, carbene and vinylidene derivatives [RuCl(η 5 -C 5 H 5 )(L){PPh 2 (2-MeC 6 H 4 )}] (L=CO 2 , CPh 2 5 , CCHPh 6 ), respectively, via displacement of one phosphine ligand. The vinylidene complex 6 promptly reacts with benzylamine affording the aminocarbene [RuCl(η 5 -C 5 H 5 ){C(NHCH 2 Ph)CH 2 Ph}{PPh 2 (2-MeC 6 H 4 )}] ( 7 ). Moreover, the cyclometalated derivative [ Ru(η 5 -C 5 H 5 ){PPh 2 (2-C H 2 C 6 H 4 )}{PPh 2 (2-MeC 6 H 4 )}] ( 4 ) has been obtained from the methyl complex [RuMe(η 5 -C 5 H 5 ){PPh 2 (2-MeC 6 H 4 )} 2 ] ( 3 ) by intramolecular C–H bond cleavage and methane elimination. Complex 1 , whose X-ray structure analysis is also reported, has been found to catalyze alkyne coupling reactions.

Highly selective induction of metal-centered chirality in the ligand exchange reaction of planar-chiral cyclopentadienyl–ruthenium complex bearing an anchor phosphine ligand

Treatment of planar-chiral cyclopentadienyl–phosphine ruthenium complexes with phosphine and phosphite induces metal-centered chirality with a high stereoselectivity (≳99 % de).

Preparation of donor-sigma-acceptor molecules using arene-ruthenium chemistry.

Several donor-sigma acceptor (D-sigma-A) molecules with thioalkyl side chains have been prepared by ruthenium-activated nucleophilic aromatic substition (S(N)Ar) reactions. Selective substitution of chloride from cyclopentadienyl(1,4-dichlorobenzene)ruthenium by using piperazine derivatives as nucleophiles is addressed. This selectivity, in combination with further manipulation of the complexes, allows the preparation of unsymmetrically functionalized tetraalkyl-p-phenylenediamine (TAPD) units which are difficult to synthesize by traditional organic S(N)Ar conditions. Phenanthroline-assisted decomplexation of the product arene-RuCp systems under UV irradiation is described.

Ruthenium Cyclopentadienyl Aryldiazenido Complexes. Synthesis of [Cp‘Ru(PR3)2(N2C6H4OMe)][BF4]2and [Cp‘RuCl(PPh3)(N2C6H4OMe)][BF4] (Cp‘ = Cp, Cp*) and X-ray Crystal Structure of [CpRu(PPh3)2(N2C6H4OMe)][BF4]2, an Aryldiazenido Complex with a Large N−N−C(aryl) Angle and Near-Linear Ru−N−N−C(aryl) Skeleton

The neutral ruthenium complexes Cp‘Ru(PR3)2Cl [Cp‘ = Cp, PR3 = PPh3, PMe3, or 1/2 dppe; Cp‘ = Cp*, PR3 = PMe3] react with [p-MeOC6H4N2][BF4] in acetone to give new cyclopentadienyl ruthenium aryldiazenido dicationic complexes [Cp‘Ru(PR3)2(N2C6H4OMe)][BF4]2 [Cp‘ = Cp, PR3 = PPh3 (1), PMe3 (2), or 1/2 dppe (3); Cp‘ = Cp*, PR3 = PMe3 (4)] in good yields. The dicationic complexes 1−3 may also be conveniently isolated in better yield by treatment of the acetonitrile ruthenium complexes [CpRu(PR3)2(NCMe)][BF4] with the arenediazonium salt. When the reaction of Cp‘Ru(PPh3)2Cl (Cp‘ = Cp or Cp*) with [p-MeOC6H4N2][BF4] is carried out in toluene, the product is instead the cyclopentadienyl ruthenium aryldiazenido monocationic complex [Cp‘RuCl(PPh3)(N2C6H4OMe)][BF4] [Cp‘ = Cp (5) or Cp* (6)]. Further, if the reaction of Cp*Ru(PPh3)2Cl with diazonium salt is carried out in acetone, the binuclear complex [Cp*RuCl(N2C6H4OMe)]2[Cl]2 (7) can be isolated in low yield in addition to 6. All new complexes 1−7 were fully char...