- Asymmetric Carbon Dioxide Insertion into a ?-Allyltitanium(III) Complex
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A ?-allyltitanium complex with a chiral cyclopentadienyl ligand reacts with carbon dioxide under mild conditions to form a carbon-carbon bond, thus providing the first demonstration of asymmetric carbon dioxide fixation.
- Sato, Fumie,Iijima, Satoshi,Sato, Masao
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- C.I.D.N.P. Enhancement of both Organometallic and Organic Compounds in the Thermal Reaction of 2Ph)Cl(η-C5H5)2> with CCl4
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The thermal reaction of with CCl4 in 2H6>benzene solution gives enhanced signals for both the starting titanium compound and product PhCH2CCl3, but not in titanocene dichloride or bibenzyl which are also produced; a mechanism accounting for these observations is proposed.
- Cardin, David J.,Kelly, John M.,Lawless, Gerard A.,Trautman, Raymond J.
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- Oxygen-Oxygen bond homolysis in a novel titanium(IV) alkylperoxide complex, Cp2Ti(OOtBu)Cl
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Cp2TiCl2 reacts with NaOOtBu to form the new titanium peroxide complex, Cp2Ti(OOtBu)Cl (1), which has been characterized both in solution and in the solid state. This complex is surprisingly unreactive towards olefins and phosphines, as it does not directly transfer an oxygen atom. Instead, decomposition occurs via initial homolysis of the oxygen-oxygen bond, yielding a tert-butoxyl radical. Decomposition of 1 in the presence of phosphines yields either phosphine oxides (e.g., OPPh3) or phosphinites (e.g., tBuOPEt2), products that result from tBuO? + PR3. O-O bond homolysis is surprising because the Ti(IV) center is d0 and cannot be oxidized, where all previous clear examples of homolytic cleavage of metal peroxide complexes are facilitated by oxidation of the metal center. Copyright
- DiPasquale, Antonio G.,Kaminsky, Werner,Mayer, James M.
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- Formation of a 1-zircona-2,5-disilacyclopent-3-yne: Coordination of 1,4-disilabutatriene to zirconocene?
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(Figure Presented) Alkyne under stress: A novel metallacycle containing one Zr atom, two Si atoms, and a C≡C bond has been prepared and its structure elucidated (Zr green, Si blue, C gray). According to X-ray data, spectral properties, and DFT calculations, the bonding situation in this compound is characterized as a l-metalla-2,5-disilacyclopent-3-yne with a weak metal-triplebond interaction.
- Lamac, Martin,Spannenberg, Anke,Jiao, Haijun,Hansen, Sven,Baumann, Wolfgang,Arndt, Perdita,Rosenthal, Uwe
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- Redox, magnetic, and structural properties of 1,3,2-dithiazolyl radicals. A case study on the ternary heterocycle S3N5C4
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The characterization of the heterocyclic radical 1,2,5-thiadiazolo[3,4-b]-1,3,2-dithiazolo [3,4-b]pyrazin-2-yl (TDP-DTA) is described. The compound is prepared by treatment of 5,6-dithiolo-1,2,5-thiadiazolo[3,4-b]pyrazine with S3N3Cl3 and purified by fractional sublimation in vacuo. The results of cyclic voltammetry and ESR analysis of TDP-DTA and related heterocyclic dithiazolyls indicate that the spin distributions and donor/acceptor properties of these radicals are extremely sensitive to the nature of the 4,5-substituents. The crystal structure of TDP-DTA has been determined at two temperatures. At 293 K, the crystals are triclinic, space group P1, with a = 4.4456(8),b = 8.40;7(2), c = 9.671(3) ?, α = 71.34(2), β = 89.28(2), γ = 87.80(2)°, Z = 2 (for C4N5S3); at 150 K the crystals are triclinic, space group P1, with a = 7.489(7), b = 9.593(4), c = 10.759(6) ?, α = 65.77(4), β = 74.10(6), γ = 74.64(6)°, Z = 2 (for C8N10S6). At 293 K the structure consists of ribbons of TDP-DTA radicals packed in a slipped π-stack arrangement. In the low temperature phase alternate layers of ribbons are shifted laterally to produce arrays of dimers. Within these dimers three long (3.401(5), 3.460(5):and 3.511(5) ?) interannular S--S contacts link the two molecules. A multiple 'tectonic plate' slippage mechanism is proposed to account for the interconversion of the two phases. The structural results are discussed in the light of variable temperature magnetic susceptibility measurements.
- Barclay,Cordes,George,Haddon,Itkis,Mashuta,Oakley,Patenaude,Reed,Richardson,Zhang
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- Preparation of spiro-cyclic organic polysulfanes of type C6H10Sn and X-ray structural analysis of C6H10S11, a derivative of cyclo-dodecasulfur
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By reaction of (C5H5)2Ti(μ-S2)2C 6H10 3 with S2Cl2 7,8,9,10,11,12-hexathiaspiro-[5.6]dodecane 4 is prepared (yield 51%) and characterized by UV, IR, Raman, mass, and NMR spectra (1H, 13C). The seven-membered CS6 ring undergoes pseudorotation in solution. With S7Cl2 the complex 3 yields 7,8,9,10,11,12,13,14,15,16,17-undecathiaspiro[5.11]heptadecane 5 (yield 23%). The yellow, monoclinic crystals of 5 consist of spirocyclic C6H10S11 molecules with the C6 ring in a chair-conformation while the CS11 ring is of the same conformation as cyclododecasulfur S12. UV, IR, Raman, mass and NMR-spectra of 5 are reported. A mixture of dichlorosulfanes SnCl2 (n = 1 - 8) reacts with 3 to give the homologous series C6H10Sm which was characterized by reversed-phase HPLC for m = 5-14. Johann Ambrosius Barth 1996.
- Steudel, Ralf,Muenchow, Vera,Pickardt, Joachim
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- DICYCLOPENTADIENYLTITANIUM(IV) PYRIDINE-2,6-DICARBOXYLATE COMPLEXES, SYNTHESIS AND STRUCTURAL CHARACTERIZATION AS PENTACOORDINATE TITANOCENE DERIVATIVES
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Reaction of (C5H5)2Ti(CH3)2 or (CH3)4C2(C5H4)2Ti(CH3)2 with pyridine-2,6-dicarboxylic acid (dipicolinic acid) yields titanocene dipicolinate derivatives.The molecular structure of (C5H5)2Ti dipicolinate is that of an axially symmetric, pentacoordinate titanocene derivative with two carboxyl oxygen atoms and the pyridine nitrogen atom as ligating atoms.Two identical chelate bite angles of only 71 deg make the dipicolinate ligand particularly suited to form a remarkably stable titanocene derivative with unprecedented pentacoordinate geometry.
- Leik, Regina,Zsolnai, Laszlo,Huttner, Gottfried,Neuse, Eberhard W.,Brintzinger, Hans H.
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- STRUCTURAL ELUCIDATION OF SOME NEW TITANACYCLES BY MEANS OF DEGRADATION AND 13C NMR STUDIES
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A reaction between diphenyltitanocene and phenyl(pentafluorophenyl)acetylene in refluxing benzene produces 1,1-bis(η5-cyclopentadienyl)-2-phenyl-3-(pentafluorophenyl)benzotitanole in 44percent yield.Degradation of the product with HCl/CHCl3 affords titanocene dichloride and Z-1,2-diphenyl-1-(pentafluorophenyl)ethene.Reaction of diphenyltitanocene and phenyl(pentafluorophenyl)acetylene in benzene under photolytic conditions results in the exclusive formation of 1,1-bis(η5-cyclopentadienyl)-2,5-diphenyl-3,4-di(pentafluorophenyl)titanole.The latter product can also be obtained in 77percent yield from a reaction between titanocene dicarbonyl and phenyl(pentafluorophenyl)acetylene in hexane solution.Application of 13C NMR spectroscopy to the structural elucidation of these and related metallacycles is discussed.
- Mattia, J.,Sikora, D. J.,Macomber D. W.,Rausch, M. D.,Hickey, J. P.,et al.
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- Synthesis of cationic (arene)IronCp complexes via arene exchange
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Rates and regioselectivity of arene exchange reactions in cationic fused arene Fe(II)Cp complexes were investigated. Thermal exchange of pyrene, naphthalenes, and cyclooctatetraene occurs in the temperature range of 90-140°C. The most labile complex in the series studied is [(η6-(1-4,4a,8a)-1,4-dimethoxynaphthalene)FeCp][PF6] having the FeCp coordinated to the substituted ring. Pyrene and other naphthalene complexes come next, followed by the cyclooctatetraene complex. Phenanthrene, veratrol, and dihydronaphthalene do not undergo exchange at temperatures up to 130°C. With Me- and OMe-substituted naphthalenes, exchange is reversible and favors the product having the metal coordinated to the non-substituted ring. The X-ray crystal structures of the two regioisomeric 1,4-dimethoxynaphthalene complexes were determined. Arene exchange in fused arene complexes is shown to be a useful synthetic method and provides new arene complexes cleanly and efficiently. The method is particularly attractive for arenes that contain functionalities that are not compatible with the Lewis acid-mediated routes. The starting materials are readily accessible via the TiCl4-assisted Cp exchange in ferrocene.
- Kündig, E. Peter,Jeger, Patrick,Bernardinelli, Gérald
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- REACTIONS D'INSERTION DU MONOXYDE DE CARBONE ET DU CYCLOHEXYLISONITRILE DANS LES LIAISONS Ti-ALKYLE ET Ti-ARYLE. PREMIER EXEMPLE DE REACTION D'INSERTION DANS UNE LIAISON METAL DE TRANSITION-LIGAND PERFLUOROARYLE
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Carbon monoxide inserts exclusively into the Ti-CH3 bond of Cp2Ti(C6F5)CH3 while cyclohexyl isocyanide inserts only into the Ti-C6F5 bond, giving Cp2TiCH3.The latter reaction is the first example of insertion into a transition metal-fluorocarbon ligand bond.Starting from Cp2Ti(C6H5)CH3, only Cp2TiCH3 is obtained.
- Dormond, A.,Dahchour, A.
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- Reduction of 1,4-dichlorobut-2-yne by titanocene to a 1,2,3-butatriene. Formation of a 1-titanacyclopent-3-yne and a 2,5-dititanabicyclo[2.2.0]hex-1(4)- ene
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The 2,5-diatanabicyclo[2.2.0]hex-1(4)-ene (bis-titanocene-fi-(Z)-1,2,3- butatriene complex) (3) is formed starting from [Cp2Ti(η 2-Me3SiC2SiMe3)] by in situ generated titanocene and 1,4-dichlorobut-2-yne via the 1-titanacyclobut-3-yne (2).
- Burlakov, Vladimir V.,Arndt, Perdita,Baumann, Wolfgang,Spannenberg, Anke,Rosenthal, Uwe,Parameswaran, Pattiyil,Jemmis, Eluvathingal D.
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- Reactions of Titana- and Zircona-cyclopentadienes with Alkynes
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Expanded metallacycles of up to 17 members have been obtained from insertion reactions of acetylenic molecules into the M-C bonds of various substituted dicyclopentadienyl-titana- and -zircona-cyclopentadienes; in one case, a zirconacyclononatetraene with mixed phenyl and methyl substituents was isolated.
- Famili, Amir,Farona, Michael F.,Thanedar, Shrinivas
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- Synthesis, properties and crystal structure of bist(cyclopentadienyl) aluminium complex [η1-(C5H5) 2AlO-iPr]2
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The reaction of Cl2AlO-iPr with C5H5Na affords the isopropoxy-bridged dimer [η1-(C5H5)2AlO-iPr]2. The compound has been characterized by NMR and
- Kunicki,Sadowski,Zachara
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- ELECTROCHEMICAL STUDIES ON ORGANOMETALLIC COMPOUNDS. II. THE OXIDATION OF TITANOCENE MONOCHLORIDE
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The electrochemical oxidation of titanocene monochloride, Cp2TiClL (L=tetrahydrofuran or dimethylphenylphosphine), has been studied by voltammetry on a disc electrode, by linear potential sweep voltammetry and by controlled potential electrolysis.A first one electron step yields Cp2TiClL+, which then reacts with Cp2TiClL to give Cp2TiCl2 and Cp2TiL+2.The latter is oxidized to Cp2TiL2+2
- Mugnier, Y.,Moise, C.,Laviron, E.
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- CARBON MONOOXIDE-INDUCED DISPROPORTIONATION OF DICYCLOPENTADIENYLTITANIUM CHLORIDE DIMER TO DICYCLOPENTADIENYLTITANIUM DICARBONYL AND DICYCLOPENTADIENYLTITANIUM DICHLORIDE
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Dicyclopentadienyltitanium chloride dimer under CO atmosphere undergoes disproportionation leading to dicyclopentadienyltitanium dicarbonyl and dicyclopentadienyltitanium dichloride.
- Battaglia, Luigi Pietro,Nardelli, Mario,Pelizzi, Corrado,Predieri, Giovanni,Chiusoli, Gian Paolo
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- ENTHALPIES OF FORMATION OF Ti(η-C5H5)2(OR)2 COMPLEXES (R = C6H5, 2-CH3C6H4, 3-CH3C6H4, 4-CH3C6H4, AND 2-ClC6H4)
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The standard enthalpies of formation of the title crystalline complexes at 298.15 K have been determined by reaction-solution calorimetry.The results give ΔHof = -379.2 +/- 8.0, ΔHfoTi(η-
- Dias, Alberto R.,Salema, Margarida S.,Simoes, Jose A. Martinho
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- Titanocene-mediated formation of phosphorus - Phosphorus bonds
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The reaction of Cp2Ti(btmsa) [btmsa = bis(trimethylsilyl) acetylene (Me3SiC≡CSiMe3)] with bulky dichlorophosphines leads to the formation of diphosphenes or dichlorodiphosphines depending on the stoichiometry used. (Me 3Si)2NN(SiMe3)PCl2 (1) was transformed either into bis[tris(trimethylsilyl)hydrazino]dichlorodiphosphine (2) or bis[tris(trimethylsilyl)hydrazino]diphosphene (3) depending on whether an excess of 1 or Cp2Ti(btmsa) was used. Depending on the starting material ratios, Cp2TiCl2 or (Cp2TiCl) 2 were obtained as byproducts besides 1 or 3. Compounds 2 and 3 were structurally characterized by X-ray diffraction. Furthermore, the known diphosphene Mes*P=PMes* (4) (Mes* = 2,4,6-tri-tert- butylphenyl) and the dichlorodiphosphine Mes*(Cl)PP(Cl)Mes* (5) were prepared by reaction of Cp2Ti(btmsa) with Mes*PCl2. The reaction of Cp2Ti(btmsa) with the sterically less demanding PhPCl2 resulted in the isolation of a triphosphinato complex. The diphosphine Ph2P-PPh2 (6) was synthesized by reaction of Ph2PCl with Cp2Ti(btmsa).
- Schaffrath, Markus,Villinger, Alexander,Michalik, Dirk,Rosenthal, Uwe,Schulz, Axel
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- DNA-metal binding by antitumor-active metallocene dichlorides from inductively coupled plasma spectroscopy analysis: Titanocene dichloride forms DNA-Cp2Ti or DNA-CpTi adducts depending on pH
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Inductively coupled plasma (ICP) spectroscopy is used to measure the DNA-metal binding of the antitumor agents Cp2TiCl2, Cp2VCl2, Cp2NbCl2, and cis-(H3N)2PtCl2/s
- McLaughlin, Mark L.,Cronan Jr., John M.,Schaller, Tamara R.,Snelling, Ronald D.
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- A novel bidentate silicon containing ligand: cyclopentadienyldimethylsilane
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The dimethylsilylcyclopentadienide anion undergoes cleavage of the silicon-cyclopentadienyl bond upon attempted complexation with transition metals.Complexes bearing such ligands can be obtained by metallation of the cyclopentadienyl ligand in tricarbonyl(η5-cyclopentadienyl)manganese, ferrocene and ruthenocene, followed by reaction with chlorodimethylsilane.The silicon-hydrogen function can react with carbonyl cobalt or carbonyl(hydrido)tris(triphenylphosphine)iridium, to give heterobimetallic complexes in which cyclopentadienyldimethylsilane acts as an assembling ligand.Similar complexes are obtained starting from tricarbonyl(η6-benzene)chromium.
- Colomer, Ernest,Corriu, Robert J. P.,Pleixats, Roser
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- Sulfur compounds. CXXXIII. Synthesis and spectra of new titanocene complexes containing the chelating ligands C2S44-, C2S52-, and C2S62-
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By analogy with the synthesis of 5-C5H5)2Ti>2C2S4 (1) from Cp2Ti(CO)2 and CS2, the compounds 2C2S4 (2) and 2C2S4 (3) were synthesized from the corresponding dicarbonyls (Me = CH3). 1 and 2 react with SCl2 in CH2C
- Steudel, Ralf,Westphal, Ursula
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- Synthesis and Reactivity of Vinylimido Complexes of Titanocene
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Tebbe's reagent (Cp2TiCH2*AlMe2Cl) or titanocene metallacyclobutanes react with nitriles in the presence of a Lewis base such as trimethylphosphine to afford vinylimido complexes of titanocene; these undergo follow-up reactions with unsaturated organic molecules to yield new heterocyclic compounds of titanocene.
- Doxsee, Kenneth M.,Farahi, Judah B.
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- Reactivity of [Cp2Ti(CO)2] and B(C6F5)3: Formation of the acylborane complexes [Cp2Ti(CO)(η2-OCB(C6 F5)3)] and [Cp2Ti(THF)(η2- OCB(C6F5)3)]
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The reaction of [Cp2Ti(CO)2] with B(C6F5)3 leads, surprisingly, as revealed by X-ray structure determination to the unexpected titana acylborane [Cp2-Ti(L)(η2-OCB(C6 F5)3)] (1, L = CO, O-outside configuration; 2, L = THF, O-inside configuration) with the tris(perfluorophenyl)borane, as a Lewis acid, attached to the carbonyl carbon atom. The acylborane picture is strengthened by a theoretical calculation (ELF).
- Choukroun, Robert,Lorber, Christian,Lepetit, Christine,Donnadieu, Bruno
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- Studies on the transferability of transition-metal-carbon and -hydrogen bond enthalpies in bis(cyclopentadienyl) complexes
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New thermochemical studies involving the complexes Ti(η5-C5H5)2(CH 3)2, Ti(η5-C5H5)2(CH3)Cl, Ti-(η5-C5H5)2(C 6H5)Cl, and W(η5-C5H5)2(H)I together with early data for the same type of molecules containing metal-carbon and metal-hydrogen bonds enabled a detailed discussion on the validity of transferring bond enthalpies. For this purpose, a method based on the bond enthalpy term concept, previously developed for complexes M(η5-C5H5)2LL′ (L = L′), was extended to molecules with L ≠ L′. This method also yields estimates of metal-ligand first bond dissociation enthalpies. The thermodynamics of the recently reported symmetrization reactions between Ti(η5-C5H5)2Cl2 and Ti(η5-C5H5)2R2 (R = CH3, C5H5) is also described in the present study.
- Calhorda, Maria J.,Dias, Alberto R.,Minas Da Piedade, Manuel E.,Salema, Margarida S.,Martinho Sim?es, José A.
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- ETUDE ELECTROCHIMIQUE DE COMPOSES ORGANOMETALLIQUES XII. ACTIVATION DE LA DOUBLE LIAISON N=N DE LA BENZOCINNOLINE PAR LE MONOCHLORURE DE TITANOCENE (Cp2TiCl)2
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The condensation at -30 deg C of benzocinnoline (RN=NR) on electrochemically prepared Cp2TiCl yields the titanium(IV) complex Cp2Ti(Cl)N(R)N(R)(Cl)TiCp2 which slowly decomposes into Cp2TiCl2 and benzocinnolinedicyclopentadienyltitanium.
- Renaud, S.,Mugnier, Y.,Roullier, L.,Laviron, E.
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- Revelation of the nature of the reducing species in titanocene halide-promoted reductions
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The fundamental nature of TiIII complexes generated in tetrahydrofuran by reduction of Cp2TiCl2 has been clarified by means of cyclic voltammetry and kinetic measurements. While the electrochemical reduction of Cp2TiCl2 leads to the formation of Cp2TiCl2-, the use of metals such as Zn, Al, or Mn as reductants affords Cp2TiCl and (Cp 2TiCl)2 in a mixture having a dimerization equilibrium constant of 3 × 103 M-1, independent of the metal used. Thus, we find it unlikely that the trinuclear complexes or ionic clusters known from the solid phase should be present in solution as previously suggested. The standard potentials determined for the redox couples Cp 2TiCl2/Cp2TiCl2-, (Cp2TiCl)2+/(Cp2TiCl)2, Cp2TiCl+/Cp2TiCl, and Cp2Ti 2+/Cp2Ti+ increase in the order listed. However, the reactivity of the different TiIII complexes is assessed as (Cp2TiCl)2 ? Cp2TiCl ≈ Cp 2Ti+ ? Cp2TiCl2- in their reactions with benzyl chloride and benzaldehyde. None of the reactions proceed by an outer-sphere electron transfer pathway, and clearly the inner-sphere character is much higher in the case of Cp2Ti + than for (Cp2TiCl)2, Cp2TiCl, and in particular Cp2TiCl2-. As to the electron acceptor, the inner-sphere character increases, going from benzyl chloride to benzaldehyde, and it is suggested that the chlorine atom in benzyl chloride and the oxygen atom in benzaldehyde may function as bridges between the reactants in the transition state.
- Enemaerke, Rasmus Juel,Larsen, Jens,Skrydstrup, Troels,Daasbjerg, Kim
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- Darstellung und Molekuelstruktur des (μ-Alkylidenamido)titanocenkomplexes 2(μ->
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Reduction of (C5H5)2TiCl2 with Zn in presence of benzyl cyanide gives the (μ-alkylideneamido)titanocene complex2> with C-C bond formation between two benzyl cyanide molecules.X-ray structure investigation indicates a symmetrical structure.The C=N distances are smaller than usual, the Ti-N distances are very short, and the Ti-N-C angle differs only a little from 180 deg, which infers a heteroallene structure of the complex.
- Rehbaum, Frank,Thiele, Karl-Heinz,Trojanov, Sergej I.
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- Kinetic results and reaction pathways of intermolecular thiolato ligand migration between titanocene complexes and from Cp2TiX(SAr) (X=Cl, SAr) to PtCl(Me)(cod) (cod=η2,η2,-1,5-cyclooctadiene)
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The mechanism of the thiolato ligand transfer from Cp2Ti(X)(SAr) (X = Cl, SAr) to PtCl(Me)(cod) (cod = η2, η2-1,5-cyclooctadiene) was established. The methyl ligand bonded to the Pt center acted as a spectator ligand throughout the reaction. Inertness of the methyl-Pt bond toward the reaction can be explained by a high degree of covalent character of the bond which inhibits ionic dissociation of the methyl ligand. Rapid and reversible disproportionation of Cp2TiCl(SAr) type complexes to afford Cp2Ti(SAr)2 had an important role in the completion of the reaction. The resulting methyl(thiolato)platinum complexes with a labile cod ligand can be used as precursors of different organoplatinum complexes.
- Osakada,Yamamoto,Hosoda
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- Electronic structure analysis and reactivity of the bimetallic bis-titanocene vinylcarboxylate complex, [(Cp2Ti)2(O2C3TMS2)]
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Multimetallic redox cooperativity features heavily in both bioinorganic and synthetic reactions. Here, the electronic structure of the bimetallic Ti/Ti complex 11, [(Cp2Ti)2(O2C3TMS2)] has been revisited with EPR, confirming a predominantly TiIII/TiIII electronic structure. Reactions of 11 with 2,6-dimethylphenyl isocyanide (CNXyl), TMSCl, MeI, and BnCl were explored, revealing differential redox chemistry of the bimetallic core. In reactions with CNXyl and TMSCl, the metallacyclic TiIII center remained unperturbed, with reactions taking place at the pendent κ2(O,O)-titanocene fragment, while reaction with MeI resulted in remote oxidation of the metallacyclic Ti center, indicative of a cooperative redox process. All structures were studied via X-ray diffraction and EPR spectroscopic analysis, and their electronic structures are discussed in the context of the covalent bond classification (CBC) electron counting method.
- Huh, Daniel N.,Maity, Asim,Powers, David C.,Schley, Nathan D.,Tonks, Ian A.,Van Trieste, Gerard P.
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- Multicomponent Pyrazole Synthesis from Alkynes, Nitriles, and Titanium Imido Complexes via Oxidatively Induced N-N Bond Coupling
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Pyrazoles are an important class of heterocycles found in a wide range of bioactive compounds and pharmaceuticals. Pyrazole synthesis often requires hydrazine or related reagents where an intact N-N bond is conservatively installed into a pyrazole precursor fragment. Herein, we report the multicomponent oxidative coupling of alkynes, nitriles, and Ti imido complexes for the synthesis of multisubstituted pyrazoles. This modular method avoids potentially hazardous reagents like hydrazine, instead forming the N-N bond in the final step via oxidation-induced coupling on Ti. The mechanism of this transformation has been studied in-depth through stoichiometric reactions of the key diazatitanacyclohexadiene intermediate, which can be accessed via multicomponent coupling of Ti imidos with nitriles and alkynes, ring opening of 2-imino-2H-azirines, or direct metalation of 4-azadiene-1-amine derivatives. The critical transformation in this reaction is the 2-electron oxidation-induced N-N coupling on Ti. This is a rare example of formal N-N coupling on a metal center, which likely occurs through an electrocyclic mechanism analogous to a Nazarov cyclization. Conveniently, these 2-electron-oxidized diazatitanacyclohexadiene intermediates can be accessed via disproportionation of the 1-electron-oxidized species, which allows utilization of weak oxidants such as TEMPO
- Pearce, Adam J.,Harkins, Robin P.,Reiner, Benjamin R.,Wotal, Alexander C.,Dunscomb, Rachel J.,Tonks, Ian A.
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supporting information
p. 4390 - 4399
(2020/03/04)
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- Method for preparing titanocene dichloride
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The invention discloses a method for preparing titanocene dichloride. The method comprises the following steps: cracking and rectifying dicyclopentadiene to prepare cyclopentadiene, carrying out a reflux reaction on the prepared cyclopentadiene and a mixed solution containing titanium tetrachloride, tetrahydrofuran and diethylamine, and carrying out post-treatment on the system after the reflux reaction to obtain titanocene dichloride. The post-treatment comprises the following steps: 1, cooling a post-reflux reaction system in an ice bath, filtering, and washing the obtained retentate with tetrahydrofuran and petroleum ether in sequence to obtain a washed retentate; 2, adding the washed retentate into a hydrochloric acid solution, stirring, and filtering to obtain a filtered retentate; and 3, sequentially washing the filtered retentate with ice water and ethanol, and drying to obtain titanocene dichloride. According to the method, the titanocene dichloride is prepared by adopting a cracking-reflux reaction-post-treatment method, so that the influence on the synthesis reaction due to the fusion of cyclopentadiene serving as a raw material can be avoided, and the purity of the titanocene dichloride prepared by adopting the method is 98% or above.
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Paragraph 0024; 0027-0035; 0038-0046; 0049-0057; 0060-0068;
(2020/06/17)
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- Synthesis method of titanocene dichloride
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The invention discloses a synthesis method of simple and environment-friendly titanocene dichloride. The synthesis method comprises the following steps: successively adding diethylamine and cyclopentadiene into an N,N-dimethylformamide solution, uniformly mixing and carrying out reflux reaction; after the reaction is ended, cooling to room temperature, decompressing and evaporating a solvent to dryness; then adding ice water for stirring, precipitating red precipitate, carrying out vacuum suction filtration and washing a solid with the ice water to obtain a titanocene dichloride coarse product; fully dissolving the titanocene dichloride coarse product with N,N-dimethylformamide, carrying out vacuum suction filtration and spin drying on filtrate to obtain the solid; recrystallizing the solid by using an ice water-dichloromethane-ethanol mixed solution, and filtering to obtain red acicular crystal and carrying out vacuum drying to obtain the titanocene dichloride. The method disclosed bythe invention has the advantages that the yield of the reaction is greatly improved under the condition of reducing the reaction time; meanwhile, an economical and environment-friendly solvent is used, so that the use of toxic and harmful solvents is avoided; the synthesis method has little hazard to the environment and is in line with the green and environment-friendly chemical synthesis concept.
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Paragraph 0016-0021
(2018/09/13)
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- Mechanistic study of the titanocene(III)-catalyzed radical arylation of epoxides
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An atom-economical and catalytic arylation of epoxide-derived radicals is described. The key step of the catalytic system is a sequential electron and proton transfer for the rearomatization of the radical σ-complex and catalyst regeneration. Kinetic, computational, spectroscopic, and cyclo-voltammetric investigations highlight the key issues of the reaction mechanism and catalyst stabilization by collidine hydrochloride. Studies employing radicophiles rule out the participation of cations as reactive intermediates.
- Gans?uer, Andreas,Von Laufenberg, Daniel,Kube, Christian,Dahmen, Tobias,Michelmann, Antonius,Behlendorf, Maike,Sure, Rebecca,Seddiqzai, Meriam,Grimme, Stefan,Sadasivam, Dhandapani V.,Fianu, Godfred D.,Flowers, Robert A.
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supporting information
p. 280 - 289
(2015/08/19)
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- Ambient-temperature carbon-oxygen bond cleavage of an α-aryloxy ketone with Cp2Ti(BTMSA) and selective protonolysis of the resulting Ti-OR bonds
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Reaction of Cp2Ti[η2-(CSiMe3) 2] with an α-aryloxy ketone produces a Ti(IV) enolate aryloxide complex. Selective protonolysis of the enolate ligand or both Ti-OR bonds can be achieved with various acids. The reaction of the enolate aryloxide with 1-phenyl-2-phenoxyethanol is catalyzed by a mixture of NEt3 and [HNEt3]X (X = OTf, BPh4).
- Desnoyer, Addison N.,Fartel, Beata,MacLeod, K. Cory,Patrick, Brian O.,Smith, Kevin M.
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p. 7625 - 7628
(2013/01/15)
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- Titanium(IV) carboxylate complexes: Synthesis, structural characterization and cytotoxic activity
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Four titanium(IV) carboxylate complexes [Ti(η5-C5H5)2 (O2CCH2SMes)2] (1), [Ti(η5-C5H4Me)2 (O2CCH2SMes)2] (2), [Ti(η5-C5H5)(η5 -C5H4SiMe3)(O2CCH2SMes )2] (3) and [Ti(η5-C5Me5)(O2CCH 2SMes)3] (4; Mes = 2,4,6-Me3C6H2) have been synthesised by the reaction of the corresponding titanium derivatives [Ti(η5-C5H5)2Cl 2], [Ti(η5-C5H4Me) 2Cl2], [Ti(η5-C5H5)(η5 -C5H4SiMe3)Cl2] and [Ti(η5-C5Me5)Cl3] and two (for 1-3) or three (for 4) equivalents of mesitylthioacetic acid. Complexes 1-4 have been characterized by spectroscopic methods and the molecular structure of the complexes 1, 2 and 4 have been determined by X-ray diffraction studies. The cytotoxic activity of 1-4 was tested against tumor cell lines human adenocarcinoma HeLa, human myelogenous leukemia K562, human malignant melanoma Fem-x, and normal immunocompetent cells, that is peripheral blood mononuclear cells PBMC and compared with those of the reference complexes [Ti(η5-C5H5)2Cl 2] (R1), [Ti(η5-C5H4Me)2Cl 2] (R2), [Ti(η5-C5H5)(η5 -C5H4SiMe3)Cl2] (R3) and cisplatin. In all cases, the cytotoxic activity of the carboxylate derivatives was higher than that of their corresponding dichloride analogues, indicating a positive effect of the carboxylato ligand on the final anticancer activity. Complexes 1-4 are more active against K562 (IC50 values from 72.2 to 87.9 μM) than against HeLa (IC50 values from 107.2 to 142.2 μM) and Fem-x cells (IC50 values from 90.2 to 191.4 μM).
- Gómez-Ruiz, Santiago,Gallego, Beatriz,?i?ak, ?eljko,Hey-Hawkins, Evamarie,Jurani?, Zorica D.,Kaluderovi?, Goran N.
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p. 354 - 360
(2010/04/04)
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- Recycling titanocene dichloride from the petasis methylenation reaction
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A simple method for recycling the titanium species used in the Petasis methylenation reaction is described. Treatment of the titanocene oxide byproduct with chlorotrimethylsilane and pyridine allows regeneration, recovery, and successful reuse of titanocene dichloride in amounts corresponding to nearly 90% of the dimethyltitanocene reagent initially employed.
- Berget, Patrick E.,Schore, Neil E.
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p. 552 - 553
(2008/10/09)
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- Non-redox-assisted oxygen-oxygen bond homolysis in titanocene alkylperoxide complexes: [Cp2TiIV(η1-OO tBu)L]+/0, L = Cl-, OTf-, Br -, OEt2, et3P
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The titanium(IV) alkylperoxide complex Cp2Ti(OOtBu)Cl (1) is formed on treatment of Cp2TiCl2 with NaOO tBu in THF at -20 °C. Treatment of 1 with AgOTf at -20 °C gives the triflate complex Cp2Ti-(OOtBu)OTf (2), which is rapidly converted to the bromide Cp2Ti(OOtBu)Br (3) on addition of nBu4-NBr. The X-ray crystal structures of 1 and 3 both show η1-OOtBu ligands. Complex 2 is stable only below -20 °C; 1H, 13C, and 19F NMR spectra suggest that it also contains an η1-OOtBu ligand. Removal of the chloride from 1 with [Ag(Et2O) 2]BAr′4 (Ar′ = 3,5-(CF3) 2C6H3) yields the etherate complex [Cp 2-Ti(OOtBu)(OEt2)]BAr′4 (4). Again, coordination of a fourth ligand to the Ti center indicates an η1-OOt-Bu ligand in 4. These peroxide complexes do not directly oxidize olefins or phosphines. For instance, the cationic etherate complex 4 reacts with excess Et3P simply by displacement of the ether to form [Cp2Ti(η1-OOtBu)(Et 3P)]BAr′4 (5). Compounds 1-5 all decompose by O-O bond homolysis, based on trapping and computational studies. The lack of direct oxygen atom transfer reactivity is likely due to the η1 coordination of the peroxide and the inability to adopt more reactive η2 geometry. DFT calculations indicate that the steric bulk of the tBu group inhibits formation of the hypothetical [Cp 2Ti(η2-OOtBu)]+ species.
- DiPasquale, Antonio G.,Hrovat, David A.,Mayer, James M.
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p. 915 - 924
(2008/10/09)
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- Synthesis and characterization of cyclopentadienyl titanium trichloride and indenyltitanium trichloride; monocyclictitanium trihalide complexes
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CpTiCl3 and IndTiCl3 are homogeneous metallocene catalysts that are produced under highly controlled conditions. Syndiotactic polymerization of styrene is carried out using these catalysts while methylaluminoxane (MAO) is used as a cocatalyst. In the present paper synthesis of CpTiCl3 was examined at first by reacting TiCl4 with CpNa, this reaction just led to formation of Cp2TiCl2 so CpNa was not a suitable Cp donor compound, therefore CpSiMe3 was used instead of CpNa. Reaction of CpSiMe3 with TiCl4, produced CpTiCl3 immediately. IndTiCl3 was synthesized by reacting IndSiMe3 and TiCl4 as well. At the end two synthetic catalysts were characterized by FTIR and 1H-NMR spectrometers. Copyright
- Masnadi, Mitra,Jamjah, Roghieh,Ahmadjo, Saeed,Nekoomanesh, Mehdi
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p. 543 - 547
(2008/10/09)
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- Preparation of 17 sulfur-rich chain-like thiaalkanes R-S x-R′-Sy-R and R-Sx-R′-S y-R′-Sz-R (x, y, z > 2) from titanocene thiolate complexes
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Two novel Cp2Ti(Cl)S3R'S3Tr complexes have been prepared by reaction of the six-membered metallacycles Cp 2TiS4R' (Cp = η5-C5H 5, R' = CMe2, 1,1-C6H10) with the sulfenyl chloride TrSCl (Tr = CPh3) at 20 °C. These complexes were treated with: (a) sulfenyl chlorides (RSCl or RSSCl) to obtain 11 new thiaalkanes of the type R-Sx-R'-Sy-R (R = Tr, 4-ClC 6H4, 2-C10H7; x = 3, y > 2), or (b) with SO2Cl2, SCl2 or S2Cl 2 to prepare six sulfur-rich species of the type Tr-S x-R'-Sy-R'-Sz-Tr (x, z = 3, y > 3), as well as Cp2TiCl2. The thiaalkanes decompose upon heating to give mixtures of various linear and cyclic polysulfanes R2S n and R'Sm. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Muenchow, Vera,Steudel, Ralf
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p. 718 - 725
(2007/10/03)
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- Carbon-carbon bond formation in the reductive coupling of trifluoroacetonitrile and pentafluorobenzonitrile - Synthetic routes to new perfluoroalkyl- and perfluoroaryl-substituted α-diimines: Versatile synthons for heterocycle synthesis
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Reductive coupling of perfluoroalkyl- and perfluoroaryl-nitriles with [(η5-C5H5)2TiCl]2 provides the corresponding μ-diiminatodititanium complexes. Protonolysis of the Ti-N bonds with ethereal HCl lib
- Diel, Bruce N.,Deardorff, Peter J.,Zelenski, Catherine M.,Incarvito, Christopher,Liable-Sands, Louise,Rheingold, Arnold M.
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p. 3902 - 3910
(2008/10/09)
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- Dimethyltitanocene: From millimole to kilomole
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The process development of a dimethyltitanocene-mediated ester olefination is described. The synthetic challenges and stability issues involving large-scale production of dimethyltitanocene are documented, and the optimization of the ester olefination is detailed. The process described was used to make hundreds of kilograms of an advanced intermediate for aprepitant (Emend).
- Payack, Joseph F.,Huffman, Mark A.,Cai, Dongwei,Hughes, David L.,Collins, Paul C.,Johnson, Brian K.,Cottrell, Ian F.,Tuma, Linda D.
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p. 256 - 259
(2013/09/04)
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- Synthese von [(η5-C5H5)2Ti(Cl)(CCSiMe3)]Ni(CO) und dessen Reaktionverhalten gegenueber Phosphiten: die Festkoerperstruktur von (CO)2Ni[P(OC6H4CH3-2)3]2
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Treatment of [Ti](Cl)(CCSiMe3) (1) {[Ti]=(η5-C5H5)2Ti} with Ni(CO)4 (2) in a 1:1 molar ratio produces the heterobimetallic early-late transition metal complex {[Ti](Cl)(CCSiMe3)}Ni(CO) (3), which features a low-valent Ni(CO) entity stabilized by a datively bonded Cl and a η2-coordinated Me3SiCC ligand. As side-products [Ti]Cl2 (8) and {[Ti](CCSiMe3)2}Ni(CO) (5) are formed. The latter complex can also be synthesized by the reaction of [Ti](CCSiMe3)2 (4) with equimolar amounts of 2. If 3 is reacted with stoichiometric amounts of P(OR)3 (6a, R=C6H5; 6b, R=C6H4CH3-2; 6c, R=C6H4t-Bu-2) the bis(alkynyl) titanocene 4, (CO)2Ni[P(OR)3]2 (7a, R=C6H5; 7b, R=C6H4CH3-2; 7c, R=C6H4t-Bu-2), complex 8, {[Ti](μ,η1:η2-CCSiMe3)}2 (9) along with Me3SiCC-CCSiMe3 (10) is produced. A possible mechanism for the formation of these species is presented. The solid-state structure of 7b is reported. Complex 7b crystallizes in the tetragonalic space group P-421c with the following parameters: a=14.852(2), b=14.852(2), c=19.410(4) Angstroem, V=4281.5(12) Angstroem3, Z=4 and ρ=1.271 g cm-3. Mononuclear 7b features a Ni(O) centre in a pseudo-tetrahedral environment, caused by the CO and P(OC6H4CH3-2)3 ligands.
- Meichel, E.,Stein, Th.,Kralik, J.,Rheinwald, G.,Lang, H.
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p. 191 - 198
(2007/10/03)
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- Coordination chemistry of stable radicals: Homolysis of a titanium-oxygen bond
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Thermolysis of Cp2TiCl(TEMPO) (TEMPO = 2,2,6,6-tetramethylpiperidine-1-oxyl) at 60 °C in a benzene/CCl4 mixture generates Cp2TiCl2. Kinetic studies implicate a mechanism involving the reversible cleavage of a Ti-O bond to generate the TEMPO radical and Cp2TiCl, which is trapped by CCl4 to give Cp2TiCl2. The rate of this reaction is strongly inhibited by added TEMPO and increases with increasing CCl4 concentration, indicating that the coupling of TEMPO to Cp2TiCl is faster than chloride atom abstraction from CCl4. Copyright
- Huang, Kuo-Wei,Waymouth, Robert M.
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p. 8200 - 8201
(2007/10/03)
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- Synthetic and electrochemical studies on 1,1′-dithia-substituted derivatives of ferrocene and structure of 1,3-dithia[3]ferrocenophane [Fe(C5H4S)2CH2]
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The bimetallic complexes fc(μ2-S)2TiCp22 (1, fc = 1,1′-ferrpcenyl, Cp = cyclopentadienyl) and fc(μ2-S2)(μ2-S)TiCp2 (2) were synthesized by reaction of fc(SH)2 with Cp2TiCl2, and from fcS3 and Cp2Ti(CO)2, respectively. The novel tetrasulfane fcS4 was obtained from 2 and SCl2. 1,3-Dithia[3]ferrocenophane fcS2CH2 was obtained from fc(SH)2 and CH2Cl2 in the presence of Cp2TiCl2 and KOH. The molecular and crystal structure of fcS2CH2 was determined by X-ray crystallography; the molecular symmetry is Cs. Electrochemical studies on the recently prepared ferrocenophanes fcS2-1-SO, fcS2-1-SO2, and fcS2-2-SO show that, with respect to fcS3, the progressive oxidation of the trisulfane bridge makes more and more difficult the fc/fc+ oxidation, whereas insertion of a Cp2Ti fragment exerts the opposite effect.
- Steudel, Ralf,Hassenberg, Karin,Pickardt, Joachim,Grigiotti, Emanuela,Zanello, Piero
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p. 2604 - 2608
(2008/10/08)
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- A new chiral metalladiphosphine for early-late chemistry. Crystal structure of a D-camphor-based zirconium enolato phosphine and rearrangement of heterobimetallic Zr/Pd complexes
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The bis(phosphinoenolato) zirconocene 2, prepared from the phosphino camphor derivative 3-exo-PPh2C10H15O 1, represents the first C2-symmetric chiral diphosphine containing an early transition metal centre tethered to the phosphino groups via an enolato linkage. It allows the selective assembly of Lewis-acid early-late bimetallic combinations, as exemplified with the Zr/Cu and Zr/Ag complexes 4 and 5. The monophosphinoenolato titanocene 3 was also prepared. Reactions of 2 or 3 with [Pd(dmba)(μ-Cl)]2 (dmba = o-C6H4CH 2NMe2) or [PdCl2(SEt2)2] led to complete transfer of the functional ligand to the Pd(II) centre, with formation of [(dmba)Pd(PPh2C10H14O)] 6 or cis-[Pd(PPh2C10H14O)2] 8 and [Cp2ZrCl2]/[Cp2TiCl2], respectively. A heterobimetallic Zr/Pd intermediate complex 10 of this rearrangement could be detected. Complexes 6 and 8 were prepared independently by reaction of 1 with [Pd(dmba)(μ-Cl)]2 or [Pd(SEt2)2Cl 2], respectively, which first afforded complexes 7 and 9 which were then treated with KH. The crystal structures of 2, 6 and 8·THF· H2O have been determined by X-ray diffraction. The Royal Society of Chemistry 2001.
- Mattheis, Chris,Braunstein, Pierre,Fischer, Axel
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p. 800 - 805
(2007/10/03)
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- Die Best?ndigkeit von (η5-C5H4R)2Ti(CCR′) 2 in Abh?ngigkeit von den elektronischen Eigenschaften der Cyclopentadienyl-Liganden. Die Festk?rperstruktur von (η5-C5H5)(η5-C 5H4SiMe3)Ti(CCSiMe3)2
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The synthesis of the titanocene dichlorides (η5-C5H5)(η5-C 5H4SiMe3)TiCl2 (3) and (η5-C5H4CO2R) 2TiCl2 (8a, R=CH3; 8b, R=CH2CH3), which contain either electron-donating or electron-withdrawing substituents at the cyclopentadienyl fragments is discussed. While the reaction of 8a or 8b with LiCCR′ in different stoichiometric ratios leads only to product mixtures from which no pure components could be isolated, treatment of 3 with two equivalents of LiCCR′ (9a, R′=C6H5; 9b, R′=tBu; 9c, R′=SiMe3) selectively produces the bis(alkinyl) titanocenes (η5-C5H5)(η5-C 5H4SiMe3)Ti(CCR′)2 (10a, R′=C6H5; 10b, R′=tBu; 10c, R′=SiMe3). However, it was found that when complex 10c is stirred in tetrahydrofuran solutions, Me3SiCC is eliminated and Me3SiCC-CCSiMe3 (11) along with [(η5-C5H5)(η5-C 5H4SiMe3)Ti(CCSiMe3)]2 (12) is formed.The solid-state structure of (η5-C5H5)(η5-C 5H4SiMe3)Ti(CCSiMe3)2 (10c) is reported. Complex 10c crystallises in the monoclinic space group Pc with two independent molecules in the asymmetric unit and with the cell constants a=20.8131(6), b=10.6615(3), c=12.2543(4) A?, β=101.12(3)°, V=2668.14(14) A?3 and Z=4. 10c exhibits a pseudotetrahedrally coordination sphere around the Ti(IV) centre comprised of the two σ-bonded alkynyl ligands Me3SiCC and the η5-coordinated cyclopentadienyl moieties C5H5 as well as C5H4SiMe3.
- Lang,Meichel,Stein,Back,Hovestreydt
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- Amido- and imido-ethylpyridine titanium complexes. Crystal structure of {Ti[NCH2CH2py]Cl2(THF)}2
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Compounds of general formula N(R1)(R2)CH2CH2py (py=C5H4N; R1=R2=SiMe3, 1a; R1=H, R2=SitBuMe2, 1b; R1=SiMe3, R2=SitBuMe2, 1c; R1=SiMe3, R2=Ph, 5) were synthesised. They readily reacted with TiCl4 to afford the corresponding amidoaminotrichlorides {Ti[N(R2)(CH2CH2py)]Cl3} (R2=SiMe3, 2a; R2=SitBuMe2, 2b; R2=Ph, 6). The related imido derivatives {Ti[N(CH2CH2py)]Cl2}n (3b) and {Ti[N(CH2CH2py)](L)Cl2}2 (L=THF, 3c; PMe3, 3d) were isolated upon heating and reaction with L, respectively. Reaction of 6 with THF afforded the corresponding adduct, {Ti[N(Ph)(CH2CH2py)](THF)Cl3} (7). Compound 3b reacted with LiNMe2 to give asymmetrical {Ti2[N(CH2CH2py)][N(CH2CH 2py)]′Cl4} (4a). Compound {CpTi[N(CH2CH2py)]Cl}n (4b), was formed when 3b reacted with NaCp. Analogous studies with 2a and 6 led to Cp2TiCl2. {Cp2Ti2[μ-N(Ph)]Cl2} (8) was isolated as the product of CpTiCl3 and Na[N(Ph)CH2CH2py]. The molecular structure of 3c was determined by X-ray single crystal diffraction.
- Ascenso, José R.,De Azevedo, Cristina G.,Dias, Alberto R.,Duarte, M. Teresa,Eleutério, Inês,Ferreira, Maria Jo?o,Gomes, Pedro T.,Martins, Ana M.
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- Carbon monoxide and tertiary phosphines as ligands in cyclopentadienyl derivatives of Group 4 elements in high oxidation state
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The titanocene dicarbonyl dication [TiCp2(CO)2][BPh4]2, (1) has been obtained in toluene under carbon monoxide by double protonation of TiCp4 with [NHnBu3][BPh4] or by two-electron oxidation of TiCp2(CO)2 with [FeCp2][BPh4]. Protonation reactions on ZrCp4 and HfCp4 proceed with elimination of 1 mol of cyclopentadiene independently on the ammonium salt/MCp4 molar ratio used. By this route the high electrophilic, solvent-free [ZrCp3]+ cation has been isolated and characterized by IR, 1H-NMR and elemental analysis. In the case of hafnium, the isolation has not been possible; nevertheless, in the presence of CO a rare example of a carbonyl derivative of hafnium(IV), [HfCp3(CO)][BPh4], has been isolated and characterized.
- Pampaloni, Guido,Tripepi, Giovanna
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- Scope of the intramolecular titanocene-catalyzed Pauson-Khand type reaction
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A Pauson-Khand type conversion of enynes to bicyclic cyclopentenones employing the commercially available precatalyst titanocene dicarbonyl is described. This methodology shows excellent functional group tolerance for a group 4 metallocene-catalyzed process. The scope and limitations of this cyclization with respect to 1,6-, 1,7- and 1,8-enynes with a variety of terminal alkyne substituents, chiral enynes, and enynes containing substituted olefins are described in detail. A mechanism involving carbonylation of an intermediate titanacyclopentene has been proposed.
- Hicks, Frederick A.,Kablaoui, Natasha M.,Buchwald, Stephen L.
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p. 5881 - 5898
(2007/10/03)
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- Coordination Chemistry of N-Alkylbenzamide-2,3-dithiolates as an Approach to Poly(dithiolate) Ligands: 1,4-Bis[(2,3-dimercaptobenzamido)methyl]benzene and Its Chelate Complex with the (C5H5)Ti Fragment
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The bidentate dithiolate ligands N,N-diethyl-2,3-dimercaptobenzamide (H2-1), bis(N,N-diethyl-2,3-dimercaptoterephthalamide (H2-2), and 1,4-bis(hydroxymethyl)-2,3-dimercaptobenzene (H4-3) were synthesized from 2,3-dimercaptobenzoic acid or 2,3-dimercaptoterephthalic acid. The air-sensitive ligands form metallocene complexes of the type [η5-C5H5)2Ti(1)] (13), [η5-C5H5)2Mo(1)] (15), [(η5-C5H5)2Ti(3)] (16), and [(η5-C5H5)2Ti(2)] (17). Complexes 15 and 16 were characterized by X-ray diffraction. Selected crystallographic details for 15 are as follows: formula C21H23MoNOS2; M = 465.49; Pbca; a = 12.536(3), b = 14.313(3), c = 22.463(3) A?; V = 4031(2) A?3; Z = 8; R = 3.56 and Rw = 4.49 for 2111 structure factors (Fo2 ≥ 3σ(Fo2)) and 254 refined parameters. The molybdenum complex 15 shows an almost planar Mo(μ-S)2C2 chelate ring. Selected crystallographic details for 16 are as follows: formula C18H18O2S2Ti; M = 378.35; P1?; a = 10.1778(11), b = 11.5806(14), c = 22.967-(3) A?; α = 96.42(1), β = 101.74(1), α = 108.82(1)°; V = 2462.3(5) A?3; Z = 6; R = 4.79 and Rw = 13.27 for 5426 structure factors (I ≥ 2σ(I)) and 766 refined parameters. All titanocene derivatives assume the envelope conformation. The free activation energy for the flip around the S-S axis was determined for 13 to be 69 kJ/mol. The bis(dithiolate) ligand 1.4-bis[(2,3-dimercaptobenzamido)methyl]benzene (H4-4) was prepared from 2,3-dimercaptobenzoic acid and converted into the dinuclear air-stable titanocene complex [{(η5-C5H5)2Ti}2(4)] (19). Complex 19 reacts with HCl/CHCl3 with liberation of free H4-4 while reaction with NMe4Cl results in an intramolecular dithiolate shift under formal liberation of [(C5H5)3TiCl] and formation of the square-pyramidal chelate complex (NMe4)[(η5-C5H5)Ti(4)], (NMe4)[20]._ Crystallographic details for (NMe4)[20]·CH2Cl2 are as follows: formula C32H35Cl2N3O2S 4Ti: M = 740.67; P1?; a = 11.579(4), b = 12.210(4), c = 14.016(4) A?; α = 112.28(2), β = 94.46(3), γ = 104.22(3)?; V = 1744.9(10) A?3; Z = 2; R = 5.35 and Rw = 12.84 for 2870 structure factors (I ≥ 2σ(I)) and 397 refined parameters. The chelate rings in [20]- assume an endo/exo conformation.
- Seidel, Wolfram W.,Ekkehardt Hahn,Lügger, Thomas
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p. 6587 - 6596
(2008/10/09)
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- Novel nine-membered titanaheterocycles - Structure, ab initio calculations, and preparative use towards the selective synthesis of substituted cyclopentanols
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Reactions of Cp2Ti(CO)2 (3) with two equivalents of α,β-unsaturated ketones 4 yield the novel titana-2,9-dioxacyclonona-3,7-dienes 5. Cross-coupling of 3 with two different ketones 4 and 6 to give 7 can be achieved under certain reaction conditions. Hydrolysis of 5 or 7 may generate diketones 9, cyclopentanols 10/11, or cyclopentenes 12/13, depending on substituents and conditions. The X-ray crystal structure of 5a, the first nine-membered bis(η5-cyclopentadienyl)-substituted titanaheterocycle containing carbon, is presented. Ab initio calculations were performed for 5a and for titana-2-oxacyclopentene 1, a conceivable intermediate in the coupling reaction.
- Hampel, Frank,Van Eikema Hommes, Nico,Hoops, Sven,Maaref, Faramarz,Schobert, Rainer
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p. 1253 - 1262
(2007/10/03)
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- Photoreactivity of titanocene pentasulfide
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The electronic spectrum of Cp2TiS5 shows a long-wavelength absorption at λmak = 492 nm which is assigned to the lowest-energy S52- → TiIV ligand-to-metal charge transfer (LMCT) transition. The photolysis of the complex in CH2Cl2 leads to the formation of Cp2TiCl2 and elemental sulfur. It is suggested that LMCT excitation initiates a reductive elimination with the extrusion of S5 while the reduced titanocene is reoxidized by the solvent.
- Kunkely, Horst,Vogler, Arnd
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p. 224 - 226
(2007/10/03)
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- Interaction of carbon dioxide with acetylene complexes of titanocene. Synthesis and structure of binuclear σ-alkenylcarboxylate complexes of titanium (III) and unexpected transformation of these complexes into titanafuranone metallacycles under the action of air oxyge.
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It has been shown that carbon dioxide reacts with acetylene complexes of titanocene Cp2Ti(RC2R) (R = Ph, SiMe3) at room temperature and atmospheric pressure to form binuclear σ-alkenylcarboxylate complexes of trivalent titanium Cp2TiC(R)=C(R)-COOTiCp2 containing two fused chelate cycles and a tricoordinated oxygen atom. The interaction of these binuclear carboxylate complexes with air oxygen at 20°C results in rapid formation of titanafuranone metallacycles Cp2 TiC(R)=C(R)-C(O)-O. X-ray diffraction studies of complexes Cp2TiC(SiMe3)=C(SiMe3)-COOTiCp2 and Cp2 TiC(Ph)=C(Ph)-C(O)-O have been carried out.
- Burlakov,Yanovsky,Struchkov,Rosenthal,Spannenberg,Kempe,Ellert,Shur
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p. 105 - 112
(2007/10/03)
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- New titanocene complexes [Cp2Ti(μ-S2)2NR] (with R = Me and nOct) as transfer reagents for the synthesis of the heterocycles S5NR and S6NR
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The reaction of 1,4-S4(NR)2 with (η5-C5H5)2Ti(CO)2 yields [Cp2Ti(μ-S2)2NR] which on treatment with SCl2 or S2Cl2
- Schumann, Oliver,Steudel, Ralf
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p. 529 - 532
(2007/10/03)
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- Synthesis and structural studies on mono- And bis(cyclopentadienyl)titanium(IV)/zirconium(IV) derivatives of ferrocenyl hydrazones
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The reactions of hydrazones, derived by the condensation of acetylferrocene with different aromatic acid hydrazides (benzoic, 2-chlorobenzoic, nitrobenzoic, methylbenzoic), with mono(cyclopentadienyl)titanium(IV) trichloride and bis(cyclopentadienyl) titanium (IV)/zirconium (IV) dichloride have been studied in anhydrous tetrahydrofuran or dichloromethane in the presence and absence of amine. Tentative structural conclusions are drawn for the reaction products based upon elemental analysis, electrical conductance, magnetic moment and spectral (electronic, infrared and 1H NMR) data.
- Srivastava,Srivastava,Gupta,Pandey,Sengupta
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p. 778 - 782
(2007/10/03)
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- Titanocene complexes of ring-opened dibenzothiophene and related dimercaptobiaryl ligands
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This paper describes organotitanium derivatives resulting from the reactions of titanocene dichloride with derivatives of dibenzothiophene (DBT). Lithium cleavage of DBT gives 2,2′-Li(LiS)C12H8 which reacts with (C5H5)2TiCl2 to give the metallacyclic complex (C5H5)2TiSC12H8 (1). Two side products were isolated in smaller amounts, the thiolates (C5H5)2Ti(SC6H4-2-Ph)2 (2) and (C5H5)2Ti(SC6H4-2-Ph)Cl. DNMR studies showed that 1 and its MeC5H4 analog 3 are stereochemically non-rigid as a result of the folding of the organosulfur chelate. The structure of (MeC5H4)2TiSC12H8 was verified by single crystal X-ray diffraction; the complex consists of the expected (MeC5H4)2Ti moiety coordinated to the carbon and sulfur of the ring-cleaved DBT. An attempt to generate 2,2′-Li(LiS)C12H8 via the double metalation of 2-phenylbenzenethiol with two equivalents of BuLi in the presence of TMEDA, followed by treatment with (C5H5)2TiCl2, gave the deep green complex (C5H5)2TiS2C24H16 (4), Single crystal X-ray diffraction indicated that 4 is a complex of the 2,2-dimercapto-3,3′-diphenylbiphenyl ligand (2,2′-(LiS)2-3,3′-Ph2C12H6), resulting from the coupling of two molecules of 1-Ph-2-LiS-3-LiC6H3. DNMR studies showed that this complex is stereochemically rigid. The free dithiol was liberated by treatment of 4 with anhydrous HCl. The complex of the unsubstituted 2,2′-dimercaptobiphenyl was prepared by treatment of 2,2′-Li(LiS)C12H8 with one equivalent of sulfur followed by quenching the reaction with titanocene dichloride to give (C5H5)2TiS2C12H8 (6). Electrochemical studies show that the TiIV/III couple is reversible for all new compounds; the reduction potentials are lower for the chelating dithiolates and highest for the C-S chelate complexes 1 and 3.
- Stafford, Philip R.,Rauchfuss, Thomas B.,Verma, Atul K.,Wilson, Scott R.
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p. 203 - 214
(2007/10/03)
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- Large sulfur-nitrogen heterocycles: Preparation of the sulfur imides S(n)NH (n = 8, 9, 11) and structures of S8NH and S9NH
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A surprisingly simple, systematic route to the title compounds is achieved by ligand transfer from [Cp2TiS-NH] to the difunctional sulfanes S(n)Cl2 (n = 1,2). This should provide new impetus to sulfur nitrogen chemistry. Whereas the structure of S9NH (shown on the right) is significantly different from that of S10, the structure of S8NH resembles that of S9.
- Steudel,Bergemann,Buschmann,Luger
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p. 2537 - 2539
(2008/10/09)
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- Sulfur Compounds, 187. Synthesis of Bis(trichloromethyl)tetra- and -heptasulfane from Titanocene Polysulfide Complexes and Structure of (CCl3)2S7
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CCl3SCl reacts with (C5H5)2TiS5 to give the heptasulfane (CCl3)2S7 which forms colorless crystals of m.p. 38 deg C.An X-ray structural analysis revealed that the C-S7-C chain is helical but the CCl3 groups are slightly tilted.In the triclinic crystals the molecules are arranged parallel to each other.Decomposition of (CCl3)2S7 provides other members of the homologous series with 4-12 sulfur atoms as shown by HPLC analysis.The reaction of CCl3SCl with (C5H4CH3)4Ti2S4 yields colorless crystals of (CCl3)2S4, demonstrating the usefulness also of dinuclear titanocene polysulfide complexes for the synthesis of organic polysulfanes.Infrared, Raman, and 13C-NMR spectra of (CCl3)2S4 and (CCl3)2S7 are reported. - Keywords: Organic polysulfanes; Titanocene compounds; Sulfur ligand transfer; Chain length equilibration; Sulfur helix
- Steudel, Ralf,Pridoehl, Markus,Buschmann, Juergen,Luger, Peter
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p. 725 - 728
(2007/10/03)
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- Thiolato ligand transfer from bis(thiolato)titanocenes to platinum(II) complexes
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Reactions of Cp2Ti(SEt)2 (1a) and Cp2Ti(S-i-Pr)2 (1b) with equimolar PtCl2(cod)2 give bis-(thiolato)platinum complexes, [Pt(SEt)2]n (2a) and [Pt(S-i-Pr)2]n (2b), respectively, accompanied by formation of Cp2TiCl2. Complexes 2a,b, which are insoluble in common organic solvents, are characterized by elemental analyses and by CP-MAS 13C NMR spectra in the solid state. Cp2Ti(SC6H4-p-Me)2 (1c), Cp2Ti(SPh)2 (1d), Cp2Ti(S2C6H4) (1e), and Cp2Ti(S2C2H4) (1f) react with equimolar PtCl2(cod) smoothly to give mixtures of Cp2TiCl2 and (thiolato)-platinum complexes with the cod ligand, Pt(SC6H4-p-Me)2(cod) (3c), Pt(SPh)2(cod) (3d), Pt-(S2C6H4)(cod) (3e), and Pt(S2C2H4)(cod) (3f), respectively. Reactions of 1a with excess PtCl2(cod) in THF and in CH2Cl2 cause a color change of the solution indicating initial formation of Cp2TiCl(SEt) followed by its further reaction with Pt complexes to give Cp2-TiCl2. The latter step, which is much slower than the former, obeys pseudo-first-order kinetics with respect to [Cp2TiCl(SEt)]. The observed rate constants, kobsd, of the reaction in CH2Cl2 are proportional to [PtCl2(cod)]. Temperature dependence of the rate constants in THF gives the kinetic parameters Ea = 57.4 kJ mol-1, ΔH? = 54.8 kJ mol-1, ΔS? = -106 J mol-1 K-1, and ΔG? = 86.3 kJ mol-1 at 298 K. Reaction of 1b with excess PtCl2(cod) also gives Cp2TiCl2 through Cp2TiCl(S-i-Pr). The kinetic parameters of the reaction are Ea = 62.3 kJ mol-1, ΔH? = 59.8 kJ mol-1, ΔS? = -124 J mol-1 K-1, and ΔG? = 96.7 kJ mol-1 at 298 K. The absorption spectrum of a reaction mixture of 1f with excess PtCl2(cod) shows a decrease in the peak due to 1f with concomitant growth of a peak due to Cp2TiCl2. The reaction obeys 0.5th-order kinetics with respect to [1f]. Reactions of 1c,d with equimolar PtCl2(cod) in toluene give the complexes formulated as [Cp2Ti(SAr)2PtCl2(cod)] (4c, Ar = C6H4-P-Me; 4d, Ar = Ph), which are characterized by elemental analyses and 13C NMR spectra in the solid state. Dissolution of 4c,d in THF causes formation of a mixture of Cp2-TiCl2 with 3c,d, respectively.
- Osakada, Kohtaro,Kawaguchi, Yasuharu,Yamamoto, Takakazu
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p. 4542 - 4548
(2008/10/09)
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- The Synthesis of Cyclic Organosulfur Compounds from (C5H4)4Ti2C2S4 by Ligand Transfer Reactions
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The tetrathiaoxalate complex Cp4Ti2C2S4 (1) reacts with an equimolar amount of COCl2 to give the blue-green mononuclear complex Cp2TiC2S4CO (4).This reaction is analogous to the known reactions of 1 with SCl2 or S2Cl2.However, when 1 was treated with equimolar amounts of the bifunctional sulfenyl chlorides 1,2-C2H4(SCl)2 (5), 1,3-C3H6(SCl)2 (6) or 1,2-C6H4(SCl)2 (7), the bi- or monocyclic tetrakisdisulfanes C6H8S8 (9b), C8H12S8 (10), and C14H8S8 (11), respectively, were obtained.The X-ray crystal structure analysis of 11*CS2 showed that 11 possesses Ci symmetry with a central exocyclic CC double bond similar to tetrathiafulvalenes: C6H4(μ-S2)2C=C(μ-S2)2C6H4. - Key Words: Titanocene complexes/ Organosulfur ligands/ Ligand transfer/ Organosulfur heterocycles/ Sulfur-sulfur bonds
- Steudel, Ralf,Westphal, Ursula,Pickardt, Joachim
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p. 561 - 564
(2007/10/02)
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- Syntheses, structures and electrochemical characterisation of mixed cyclopentadienyl/dithiolene complexes of Ti(IV)
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Cp2Ti(dithiolene) complexes are prepared by reacting Cp2TiCl2 with various dithiolenes, such as dmit2- (1,3-dithiole-2-thione-4,5-dithiolate) or dddt2- (5,6-dihydro-1,4-dithiine-2,3-dithiolate), and their X-ray crystal structures are reported.Cp2Ti(dmit) crystallizes in the monoclinic system, SG C2/c with a=23.651(5), b=10.168(2), c=16.025(6) Angstroem, β=129.51(2) deg, Z=8.Cp2Ti(dddt) crystallizes in the monoclinic system, SG P21/c with a=12.597(2), b=10.945(3), c=21.300(2) Angstroem, β=94.38(1) deg, z=4, with two independent molecules in the unit cell.In both compounds the TiS2C2 ring is folded along the S-S axis, by 47.4(3) deg in Cp2Ti(dmit) and by 49.2(1) and 51.2(1) deg in Cp2Ti(dddt).The dynamics of the ligand folding were characterized by variable temperature 1H NMR studies, which show a relationship between the coalescence temperature, the activation energy ΔG and the actual folding angle.Treatment of Cp2TiCl2 with two dmit2- equivalents affords the CpTi(dmit)2- anion, isolates as its n-Bu4N+ salt.It crystallizes in the triclinic system, space group P-1 with a=10.003(3), b=10.329(4), c=19.154(3) Angstroem, α=81.36(2), β=75.67(2), γ=67.73(2) deg, Z=2.A rationale for the observed puckering of the dithiolene ligands in both types of complexes is given by extended Hueckel calculations.For every compound investigated by cyclic voltammetry, a reversible reduction wave attributable to the Ti(IV)-Ti(III) process was observed while the oxidation leads to an irreversible ligand-centered process. dithiolene ligand / cyclopentadienyl ligand / titanium(IV) complexes / variable-temperature 1H NMR / X-ray crystal structures / EH calculations
- Guyon, Fabrice,Lenoir, Christine,Fourmigue, Marc,Larsen, Jan,Amaudrut, Jacques
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p. 217 - 226
(2007/10/02)
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- Macrocyclic titanium thiolate metalloligands: Complexation and thiolate-transfer reactions with copper(I), nickel(II), palladium(II)
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The reaction of Cp2ZrMe2 with (HSCH2CH2)2S affords the S6 macrocyclic complex [Cp2Zr(SCH2CH2)2S]2 (5). This compound crystallizes in the orthorhombic space group Pbcn with a = 15.463(5) ?, b = 14.049(5) ?, c = 14.399(5) ?, V = 3128(3) ?3, and Z = 8. Related titanocene derivatives were prepared via the reaction of Cp2TiCl2 with extended dithiols in the presence of base. In these cases, both monometallic and bimetallic macrocycles were formed and separated via column chromatography. In this way the following compounds were purified and characterized: Cp2Ti(SCH2CH2)2S (6), [Cp2Ti(SCH2CH2)2S]2 (7), [Cp2TiCl]2(SCH2CH2)2S (8), Cp2Ti((SCH2-CH2CH2)2S) (9), [Cp2Ti(SCH2CH2CH2) 2S]2(10),Cp2Ti((SCH2CH 2SCH2)2CH2) (11), [Cp2Ti((SCH2CH2SCH2) 2-CH2)]2 (12), and Cp2Ti(SCH2CH2SCH2R)2 (R = CH3 (13), Ph (14)). The interaction of these macrocycles with Cu(I) demonstrates their varying ability to act as metalloligands. In the case of 6, 7, and 9-12, binding of Cu(I) is weak at best. In contrast, the S4 macrocycle 11 complexes Cu(I) effectively to give the heterobimetallic complex [Cp2Ti(SCH2CH2SCH2) 2CH2Cu][PF6] (15). Complex 15 crystallizes in the triclinic space group P1 with a = 10.526(5) ?, b = 10.952(3) ?, c = 10.154(4) ?, α = 95.84(4)°, β = 103.75(4)°, γ = 99.02(3)°, V = 1111.2(8) ?3, and Z = 2. An electrochemical study of 15 shows that it undergoes an irreversible reduction at -0.90 V vs the Ag/AgCl electrode. This is in contrast to that observed for related Ti-Cu macrocyclic species. Extended Huckel and Fenske-Hall molecular orbital calculations are consistent with dative metal-metal interactions in 15. Further, they suggest that the Ti-S bonds are weakened by reduction. Similar bonding of Cu(I) by 13 affords the species [Cp2Ti(SCH2CH2SCH2Me) 2Cu][PF6] (18) while the 24-membered-ring S8 macrocycle 12 interacts with 1 equiv of Cu(I) to give the species [(Cp2Ti(SCH2CH2SCH2) 2CH2)2Cu][PF6] (16), in which Cu(I) binds the central four sulfur atoms. Further reaction of 16 with additional Cu(I) leads to Ti-S bond cleavage and affords 2 equiv of 15. The observation of this rearrangement prompted an examination of thiolate-transfer reactions. Reaction of 7 with the Ni(II) salts [Ni(H2O)6][BF4]2 and NiCl2 results in the formation of [Ni2(SCH2CH2SCH2CH 2S)2] (19) and Cp2TiF2 or Cp2TiCl2, respectively. Similarly, the reaction of 14 with [Pd(NCMe)4][BF4]2 affords the species [Pd6(SCH2CH2SCH2Ph) 8][BF4]4 (20). The complex 20·0.5C6H6·2NCCH3 crystallizes in the triclinic space group P1 with a = 14.605(5) ?, b = 15.110(4) ?, c = 13.248(4) ?, α = 110.86(2)°, β = 98.71(3)°, γ = 98.53(3)°, V = 2635(4) ?3, and Z = 2. The chemistry described herein indicates that while titanocenedithiolate macrocycles are capable of complexation of late metals in some cases, ring size and the Lewis acidity of the late metal may act to destabilize the Ti-S bonds, resulting in thiolate-transfer reactions.
- Huang, Yujin,Drake, Robert J.,Stephan, Douglas W.
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p. 3022 - 3028
(2008/10/08)
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- Sulphur compounds. CXLV. Synthesis and properties of Cp2TiS2SiR2, Cp2TiS2GeR2, and Cp'2TiS2SnR2 (Cp = η5-C5H5, Cp' = η5-C5H4CH3, and R = C6H5)
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The halides (C6H5)2SiCl2, (C6H5)2GeBr2, and (C6H5)2SnCl2, react with Li2S and (η5-C5H4R)2TiCl2 (R = H, CH3) to give respectively the four-membered titanacycles Cp2TiS2Si(C6H5)2, Cp2TiS2Ge(C6H5)2, and Cp'2TiS2Sn(C6H5)2 which have been characterized by 1H NMR, mass and UV spectroscopy.The new compounds form green crystals, which react with sulphur chlorides with precipitation of (C5H4R)2TiCl2.This reaction provides a route to formerly unknown sulphur-rich heterocycles of Group 14 elements.
- Albertsen, Joerg,Steudel, Ralf
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p. 153 - 158
(2007/10/02)
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- Influence electronique et sterique du ligand tetramethylcyclopentadienyle sur les proprietes physiques et sur la reactivite de complexes du titane et du zirconium
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The complexes (C5Me4H)2MR1R2 (M=Ti, Zr) and (C5Me4H)(C5H5)MR1R2 (M=Ti) have been prepared (R1=R2=Cl, CH3, C6H5, p-C6H4CH3, CO; R1=Cl, R2=CH3, C6H5, p-C6H4CH3).The NMR and IR spectra of these complexes indicate that C5Me4H exhibits an electron-donor effect more important than C5H5 and a little bit weaker than that of C5Me5.A structural investigation of the complex (C5Me4H)2Zr(C6H5)Cl and the study of the 1H or 13C dynamic NMR properties of the compounds (C5Me4H)2MR1R2 (M=Ti, Zr; R1=R2=C6H5, p-C6H4CH3; R1=Cl, Br, R2=C6H5, p-C6H4CH3) show clearly that C5Me4H has a steric effect intermediate between C5H5 and C5Me5.The steric or electronic effects of C5Me4H have been used to induce specific isomerization reactions of various alkenes by using (C5Me4H)2Ti(CH3)2 as catalyst. --- Key words: zirconium, titanium, tetramethylcyclopentadienyl, photo-assisted, isomerization.
- Courtot, P.,Pichon, R.,Salaun, J. Y.,Toupet, L.
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p. 661 - 672
(2007/10/02)
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- Spectroscopic Characterization of the Selenium-Rich Heterocycles Se5S, Se7S, and 1,5-Se6S2
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Selenium Sulfides, HPLC, Raman Spectra, 77Se NMR Spectra, X-RaySe5S in CS2 solution at 20 deg C spontaneously decomposes to give a mixture of 8 selenium-rich cyclic molecules which have been identified by reversed-phase HPLC and 77Se NMR spectroscopy as Se6, Se7, Se8, Se6S, Se7S, 1,2-Se6S2, 1,5-Se6S2, and 1,4-Se4S2.NMR spectra of Se5S, Se7S, and 1,5-Se6S2 have been measured for the first time; Raman spectra of solid Se5S and Se7S as well as crystal data of Se7S are reported in addition.A mechanism based on nucleophilic attack on Se5S is proposed for the formation of the products.
- Steudel, Ralf,Papavassiliou, Maria,Baumgart, Frank
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p. 1674 - 1678
(2007/10/02)
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- Synthesis and formal [4 + 2] cycloaddition reactions of vinylimido complexes of titanocene
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Sources of the methylidene complex of titanocene, Cp2Ti=CH2, react with nitriles in the presence of donor ligands to afford vinylimido titanocene complexes. The vinylimido complexes react readily with ketones, nitriles, and imines, y
- Doxsee, Kenneth M.,Farahi, Judah B.,Hope, H?kon
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p. 8889 - 8898
(2007/10/02)
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