- Preparation of metallacyclic titanocene hydrocarbyl complexes and their use in propene polymerization reactions
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A series of differently-substituted bis(cyclopentadienyl)titanaindan complexes has been prepared, characterized, and employed as transition metal components of homogeneous titanocene/alumoxane Ziegler-type catalysts for propene polymerization reactions.The titanaindan systems 3a and 3b were synthesized via an aryne titanocene intermediate by means of thermolysis of Cp2TiPh2 (1a) or (H3CC5H4)2TiPh2 (1b) in the presence of ethylene.The analogous reactions of 1a, b with propene, 1-pentene or 1-decene gave the corresponding 3-substituted 1,1-bis(cyclopentadienyl)titanaindan systems (4a-d).The t-butyl Cp-substituted diphenyltitanocene complexes CpTiPh2 (1c) and 2TiPh2 (1d) reacted in a different way.Their thermolysis proceeded cleanly by means of intramolecular C-H activation at the t-butyl substituent by the reactive aryne ligand to give the metallacyclic systems (RC5H4)Ph (5) (a: R = H; b: R = CMe3).The titanaindan complex 3a has been characterized by X-ray diffraction.
- Erker, Gerhard,Korek, Uwe,Petrenz, Ralph,Rheingold, Arnold L.
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- Living organotitanium(IV)-catalyzed polymerizations of isocyanates
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An organotitanium(IV) compound, TiCl3OCH2CF3, 1, was found to polymerize n-hexyl isocyanate to high yields and without the formation of cyclic trimer. CpTiCl2L (L = -OCH2CF3, -N(CH3)2, -CH3), 2-4, respectively, likewise polymerized n-hexyl isocyanate but also polymerized isocyanates in the presence of donor solvents and isocyanates possessing donor functional groups, activated olefins, and strained olefins. The activity of the organotitanium(IV) catalysts decreased with increasing steric bulk about the metal center and increasing electron donation to the metal center from the ligands. The polymerization of n-hexyl isocyanate using organotitanium(IV) compounds is living. The PDIs of PHIC synthesized using catalysts 1-4 were found to range from 1.05 to 1.2. The molecular weight of the polymer formed in polymerizations of n-hexyl isocyanate using catalysts 1-4 varied linearly as a function of the monomer-to-initiator ratio and the percent conversion of the polymerization. Polymerizations using 2 can be endcapped quantitatively, and well-defined block copolymers can be synthesized using catalysts 1-4. The kinetics for polymerizations using catalysts 1 and 2 are first-order in both monomer and catalyst (k1 = 8.5 x 10-4 mol L-1 s-1, k-1 = 3.8 x 10-4 s-1). The active endgroup of a polymerization using 3 was observed using IR spectroscopy, and the frequency of the IR stretch (1548 cm-1) was consistent with an η2-amidate endgroup structure. Finally, the kinetic data for the polymerization of n-hexyl isocyanate and the known chemistry of CpTiCl2L compounds were found to be consistent with a propagation step that occurs via a bifunctional activation mechanism.
- Patten, Timothy E.,Novak, Bruce M.
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- REACTIONS OF TRIMETHYLSILYLCYCLOPENTADIENE DERIVATIVES WITH TITANIUM, NIOBIUM, AND TANTALUM HALIDES
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The use of trimethylsilyl derivatives as effective reagents for the new or improved syntheses of complexes of the early transition metals is described.Improved routes, involving the use of trimethylsilylcyclopentadiene, are described for the syntheses of , , , , and (cp=cyclopentadienyl).Routes, involving the use of bis(trimethylsilyl)cyclopentadiene, are described for the syntheses of the analogous complexes , where X=Cl, Br, or I.The reactions of , , and with a variety of bidentate ligands are described.The Lewis acidity of these titanium compounds is much reduced from that of the parent tetrahalides and only two adducts have been positively identified: these are *phen (phen=o-phenanthroline) and *pdma (pdma=o-phenylenebisdimethylarsine).
- Cardoso, Ana M.,Clark, Robin J. H.,Moorhause, Stephen
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- LITHIUM NITRIDE REDUCTION OF Cp2TiCl2 and CpTiCl3: THE SYNTHESIS OF (Cp2TiCl)2, (Cp2TiCl2)n, Cp2Ti(CO)2 AND CHLOROTETRATITANIUM AND NITRIDOHEXATITANIUM COMPLEXES
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Stoichiometric reactions of Cp2TiCl2 or CpTiCl3 with Li3N in various molar ratios result in reduction to (Cp2TiCl)2, (CpTiCl2)n and (CpTiCl)4 and provide useful synthetic routes.Further reduction produces hexanuclear nitrido titanium clusters,
- Kilner, Melvyn,Parkin, Gerard
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- MONOALKYL- AND MONOARYL-AMIDOTITANIUM COMPLEXES
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A series of new monoalkyl- and monoaryl-amido complexes, CpTiCl2NHR (R=Et, i-Pr, t-Bu, Ph), has been synthesized and characterized.They were made in essentially quantitative yields by a very convenient reaction of CpTiCl3 with Me3SiNHR.The new complexes yield NMR and IR spectroscopic data for monoalkylamido complexes, such data being previously scarce.The compounds have very reactive amido hydrogen atoms, as is demonstrated by their thermal decomposition and their reaction with (Lewis) bases such as amines or organoalkali compounds.The products are the new bridged imido complexes, (CpTiCl)2(μ-NR)2.
- Jekel-Vroegop, C. T.,Teuben, J. H.
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- The synthesis and electrochemistry of CpTiCl2(OR) (R = alkyl, aryl) complexes
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The syntheses of several new CpTiCl2(OR) (R = alkyl, aryl) complexes are described.It was possible to isolate pure product when the R group is substituted such as to cause steric crowding at the metal centre; for example, particularly good yields of the p
- Fussing, Ingrid M. M.,Pletcher, Derek,Whitby, Richard J.
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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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- 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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- New Amido- and Imido-titanium Complexes
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cpTiCl3 (cp=η5-C5H5) in reaction with Me3SiN(H)R (R=Et, iPr, tBu, or Ph) yields the amido complexes cpTi(Cl)2N(H)R, which react further by HCl abstraction to give the corresponding centrosymmetric binuclear imido complexes 2(μ-RN)2; s
- Vroegop, Christina T.,Teuben, Jan H.,Bolhuis, Fre van,Linden, Johannes G. M. van der
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- HYDROMETALLATION OF 1-OCTENE WITH GRIGNARD REAGENTS, ALKYLMAGNESIUMS AND ALKYLMAGNESIUM HYDRIDES CATALYZED BY DICYCLOPENTADIENYLTITANIUM DICHLORIDE
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The hydrometallation of 1-octene by a series of Grignard reagents (EtMgCl, EtMgBr, n-PrMgCl, i-PrMgCl, n-BuMgCl, sec-BuMgCl, iso-BuMgCl, iso-BuMgBr and iso-BuMgI), dialkylmagnesium compounds (Me2Mg, Et2Mg, n-Pr2Mg, iso-Pr2Mg, n-Bu2Mg, sec-Bu2Mg, iso-Bu2Mg and t-Bu2Mg), alkylmagnesium hydrides (RMgH, where R = Me, Et, t-Bu, Cp and Ph) and magnesium hydrides (MgH2, HMgCl and HMgBr) in the presence of 5 molpercent dicyclopentadienyltitanium dichloride (Cp2TiCl2) in THF has been investigated.The percent yield of octane (produced on hydrolysis of the product) vs. time was plotted for several reactions in order to compare the effect of individual reagents.Most alkylmagnesium compounds with β hydrogen atoms gave primarily the hydrometallation product, although t-Bu2Mg produced isomerized starting material.MeMgH gives the best yield of octane on hydrolysis of the reaction mixture.A mechanism is proposed which accounts for all observations.
- Ashby, E. C.,Ainslie, Richard D.
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- SYNTHESIS AND CHARACTERIZATION OF BIS-BENZYL AND BIS-ALLYL COMPLEXES OF TITANIUM(III) AND VANADIUM(III); CATALYTIC ISOMERIZATION OF ALKENES WITH CpV(η3-C3H5)2
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Reactions of CpTiCl2 (Cp = η5-C5H5) with RMgX (X = Cl, Br) yield the complexes CpTiR2 (R = CH2Ph, η3-C3H5).The complex Cp*Ti(η3-C3H5)2 (Cp* = η5-C5Me5) was prepared analogously from Cp*TiCl2(THF).CpVCl2(PEt3)2 and Cp'VCl2(PEt3)2 (Cp' = η5-C5H4Me) were used for the preparation of CpV(CH2Ph)2, CpV(η3-C3H5)2, CpV(η3-1-MeC3H4)2 and Cp'V(η3-C3H5)2, respectively.The corresponding Cp*V derivatives could not be obtained.The reaction of CpCrCl2(thf) with C3H5MgCl gives a dimeric complex 2, propably via intermediate formation of CpCr(C3H5)2.CpV-bis-allyl complexes are active in the catalytic isomerization of alkenes; a 1,3-hydride shift via a ?-allylmetal hydride species is proposed.In contrast no activity in isomerization was observed for CpTi(C3H5)2 and Cp*Ti(C3H5)2.
- Nieman, J.,Pattiasina, J. W.,Teuben, J. H.
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- Bildung von μ-Oxo-bis(ν5-cyclopentadienyldichlorotitan(IV)) aus η5-Cyclopentadienyl-tris(methylselenolato)titan(IV)
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The recrystallization of CpTi(SeCH3)3 (1) from methylene chloride/pentane (1:1) in the presence of traces of moisyure over a period of 18 monaths at -18 deg C afforded the species 2O (2a) (65percent), CpTiCl3 (2b) (10percent) and 2 (2c)
- Gowik, Petra,Klapoetke, Thomas,Pickardt, Joachim
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- DARSTELLUNG, STRUKTUR UND EIGENSCHAFTEN DES DREI-KERNIGEN TITANKOMPLEXES (?-C5H5)2TiCl-O-Ti(?-C5H5)Cl-O-TiCl(?-C5H5)2*CHCl3
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The trinuclear titanium(IV) complex (?-C5H5)2TiCl-O-Ti(?-C5H5)Cl-O-TiCl(?-C5H5)2*CHCl3 is formed by hydrolysis of (?-C5H5)2TiCl2 at pH > 3.5 and can be isolated in the crystalline state from the reaction of (?-C5H5)2TiCl2 with Ag2O and water in chloroform
- Klein, Heinz-Peter,Thewalt, Ulf,Doeppert, Karl,Sanchez-Delgado, Roberto
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- Steric influences in cyclopentadienyl-monophenoxide complexes of titanium(iv) arising from ortho-substitution of the phenoxide ligand
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Reaction of [CpTiCl3] with 1 equiv. of Me3SiOC6H4CMe3-4 in benzene or thermalisation with an excess of neat Me3SiOC6H4CMe3-4 gives good yields of crystalline [CpTiCl2(OC6H4CMe3-4)] (1) for which an X-ray crystal structure determination shows a distorted tetrahedral geometry. Reaction of [CpTiCl3] and Me3SiOC6H3CMe3-2-Me-4 via the benzene solvent method or the direct thermalisation gives rise to crystalline [CpTiCl2(OC6H3CMe3-2-Me-4)] (2) for which an X-ray crystal structure determination shows a distorted tetrahedral geometry little changed from complex 1 but with the phenoxide ligand ring rotated so that two of the tert-butyl group methyls straddle one chloro ligand. Refluxing [CpTiCl3] and Me3SiOC6H4Ph-4 in toluene gave crystalline [CpTiCl2(OC6H4Ph-2)] (3) which X-ray crystallography shows has a distorted tetrahedral geometry little changed from 1 or 2. The phenoxide ligand ring is rotated less in 1 than in 2 or 3 with the 2-phenyl substituent sited between the chloro and Cp ligands. The complexes differ only in the interplanar angle between the Cp and phenoxide ligand phenyl rings [6.4(1)° for 1, 29.4(1)° for 2 and 22.2(1)° for 3]. DFT calculations carried out on 2 are in good agreement with the X-ray crystal structure. A relaxed PES scan shows that the tert-butyl group in the complex cannot freely rotate past the adjacent chloro ligand and is essentially locked in close proximity to it. There is a shallow minimum (2 kJ/mol within a range of 60 degrees) for the Ti-O-C-C dihedral angle indicating there is sufficient torsional motion within the molecule to accommodate the tert-butyl group in the observed position.
- Nielson, Alastair J.,Harrison, John A.,Shen, Chaohong,Waters, Joyce M.
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p. 1729 - 1736
(2008/10/09)
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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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- Structural studies of complexes of vanadium(III) and titanium(IV) with N,N-dimethylaminoniethylferrocenyl
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Vanadium(III) and titanium(IV) complexes containing 12-16 valence-shell electrons have been synthesised by treatment of cyclopentadienylmetal halides with the lithium salt of N,N-dimethylaminomethylferrocene, Li(FcN). The structurally characterized products were [(η5-C5H5)2Ti(η 1-FcN)Cl] 1, [(η5-C5H5)Ti(FcN)xCl3 -x)] (x = 1, complex 2; x = 2, complex 3; and x = 3, complex 4) and [V(FcN)2Cl] 6. They contain FcN bound either monodentate, through the aromatic 2-carbon atom, or bidentate, through that carbon and the amine nitrogen. Despite employing a variety of spectroscopic techniques, we were unable to distinguish the mode of binding in any way other than a crystal structure analysis. Compound 4 changes spontaneously at room temperature into the structurally characterised [(η5-C5H5)Ti(FcN)(FcN′)] 5. The ligand FcN′ arises by metallation of one methyl group of one FcN in 4 with elimination of H(FcN). This kind of metallation has not been recognised hitherto in titanium or vanadium FcN chemistry, and it may explain why yields of required products are sometimes very low. The synthetic and structural versatility of the ligand FcN have been clearly demonstrated.
- Hitchcock, Peter B.,Hughes, David L.,Leigh, G. Jeffery,Sanders, J. Roger,De Souza, Jaisa S.
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p. 1161 - 1173
(2007/10/03)
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- Synthesis and structural studies of mono(cyclopentadienyl)titanium(IV) derivatives of acetylferrocenyl thiosemicarbazones
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The reactions of thiosemicarbazones, derived by the condensation of acetylferrocene and different thiosemicarbazides (phenyl thiosemicarbazidel 4-chlorophenyl thiosemicarbazide, 4-nitrophenyl thiosemicarbazide, 2- methylphenyl thiosemicarbazide. 4-methylp
- Sengupta,Pandey,Srivastava,Srivastava
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p. 1066 - 1069
(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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- Reactivity of early-transition-metal fulvene complexes. Transformation of a 2,3,4,5-tetramethylfulvene ligand into a bidentate dialkoxide with four asymmetric carbon atoms. Molecular structure of Ti[(OCHPh)2C5Me4(CH2)]Cl2
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Cp*FvTiCl (1; Cp* = η5-C5H5, Fv = η6-C5Me4CH2) reacts with benzaldehyde, yielding Cp*Ti[(OCHPh)2C5Me4(CH2)]Cl (2) as the result of insertion in two Ti-C bonds at the 2- and 4-positions of the fulvene ligand in 1. Complex 2 reacts with HCl to give Cp*TiCl3 (3) and the corresponding dialcohol and with TiCl4 to give 3 and Ti[(OCHPh)2C5Me4(CH2)]Cl2 (5). X-ray diffraction analysis of 5 shows it to be a dialkoxide-dichloride monomeric titanium complex with a tetrahedral arrangement of the ligands around the metal center. Crystal data for C24H26Cl2O2Ti: monoclinic, P21/n, a = 10.602 (5) A?, b = 14.157 (4) A?, c = 15.274 (5) A?, β = 103.76 (3)°, V = 2227 (1) A?3, Z = 4, R = 0.037.
- Fandos, Rosa,Teuben, Jan H.,Helgesson, G?ran,Jagner, Susan
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p. 1637 - 1639
(2008/10/08)
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- CYCLOPENTADIENYL-METAL BOND CLEAVAGE AND STEREOSPECIFIC BROMINATION. THE STRUCTURE OF (η-C5H5)2Ti(OOCPh)2 AND ITS REACTIONS WITH BROMINE
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The 13C and 1H nmr spectra as well as the X-ray structure determination for (η-C5H5)2Ti(OOCPh)2 are described.The compound crystallizes in space group P212121 with a = 7.5135, b = 12.5166, c = 21.1416 Angstroem, Z = 4, dcalcd = 1.40 g cm-3 (MoKα1, λ = 0.70932 Angstroem).The structure was solved with MULTAN using data collected at 115 K and refined to the final R = 0.059 for 1500 significant reflections.The molecule has two different carboxylate ligands, one of which has a Ti-O-C angle of 135.4(6) deg and longer Ti-O (1.976(5) Angstroem) and O-C (1.300(10) Angstroem) bonds while the other has a Ti-O-C angle of 157.0(7) deg with shorter Ti-O (1.913(6) Angstroem) and O-C (1.267(10) Angstroem) bonds.With bromine, ring cleavage occurs giving C5H5Br3 or C5H5Br5 in which bromination has occurred stereospecifically.The same reaction occurs with chlorine but not with iodine or iodine monochloride.Related reactions have been observed with (η-C5H5)2MCl2 (M = Ti, Zr, and V).A non-radical mechanism is proposed in which the LUMO and HOMO of Br2 interact simultaneously with one cyclopentadienyl ring and with the metal.This interaction is a consequence of the structure of (η-C5H5)2M(OOCPh)2.
- Lucas, C. Robert,Gabe, Eric J.,Lee, Florence L.
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p. 429 - 434
(2007/10/02)
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- Effects of methyl substituents at the cyclopentadienyl ligand on the properties of C2H5TiCl3 and C5H5TiAl2CL8-x(C2H5)x (x = 0-4) complexes
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The methyl substituents in the series of pTiCl3 compounds (p = Cp, MeCp, Me3Cp, Me4Cp, Me5Cp and EtMe4Cp) shift the position of their CT absorption band from λ = 384 nm to max. 438 nm and decrease the rate of reduction of pTiCl3 by ethylaluminium
- Mach, Karel,Varga, Vojtech,Antropiusova, Helena,Polacek, Jindrich
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p. 205 - 216
(2007/10/02)
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- Synthetic and reactivity studies on (C5H5)2Ti(μ-SH)2Mo(CO) 4 and related compounds
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The compounds (RCp)2Ti(SH)2 (RCp = η5-C5H4R; 1a, R = H; 1b, R = CH3) react with C7H8M(CO)4 (M = Mo, W) to form the dimers (RCp)2Ti(μ-SH)2M(CO)4 (2a, R = H, M = Mo; 2b, R = CH3, M = Mo; 3, R = H, M = W) which were characterized analytically and spectroscopically. The reactivity of 2a,b differs sharply with that observed for 1a,b. While 1a,b show little nucleophilicity at sulfur, compounds 2a,b react with Ph2E2 (E = S, Se), S8, (RCp)2TiS5, and CH2=CHCO2Me to give (RCp)2Ti(EPh)2, (RCp)2TiS5, 1,4-[(RCp)2Ti]2S4, and (RCp)2Ti(SCH2CH2CO2Me) 2Mo(CO)4, respectively. 1H NMR studies show that the bimetallic compounds prepared in this study exist as a mixture of syn and anti isomers which differ in the relative orientation of the hydrogen substituent on the sulfur. Through DNMR studies it was shown that interconversion of these isomers occurs with ΔG* ≈ 72 kJ/mol which is comparable to the barriers found for other SR-bridged 34-electron dimers. While the facility of the isomerization process is unaffected by acid, catalytic quantities of triethylamine has an accelerating effect. Reaction of 2a,b with strong bases gives the highly reactive dianions which were isolated in pure form using bulky counterions.
- Ruffing, Charles J.,Rauchfuss, Thomas B.
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p. 524 - 528
(2008/10/08)
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- PHOTOCHEMISTRY AND ELECTRONIC STRUCTURE OF THE ( eta 5-C5H5)2TiS5 COMPLEX.
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The Cp//2TiS//5 complex (Cp equals eta **5-C//5H//5) is photochemically quite unreactive. The complex does not react with acetylenes, CO, phosphites, or amines at either high- or low-energy irradiation wavelengths. The complex does react with halocarbons to afford Cp//2TiX//2 (X equals halide) and it reacts with organic disulfides (RSSR) to give Cp//2Ti(SR)//2 complexes. However, the quantum yields for these reactions are quite low (e. g. , phi //3//6//6 equals 6 multiplied by 10** minus **3 for the reaction with CCl//4; phi //3//6//6 equals 2 multiplied by 10** minus **3 for the reaction with PhSSPh). Flash photolysis of the complex produces a transient that decays by first-order kinetics (k equals 2 multiplied by 10**4 s** minus **1). The transient is proposed to be a species in which a single Ti-S bond has been cleaved. Rapid reformation of the Ti-S bond is suggested to be the reason for the photochemical inertness of the complex.
- Bruce,Bruce,Tyler
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p. 6660 - 6664
(2007/10/02)
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- SYNTHESIS AND PROPERTIES OF A THERMALLY STABLE METHYLTITANIUM(IV) COMPOUND: CYCLOPENTADIENYLMETHYLDICHLOROTITANIUM(IV)
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η5-C5H5Ti(CH3)Cl2 and η5-C5H5Ti(C2H5)TiCl2 have been synthesized.The reactivity of the methyl compound is much greater than that of the closely related sandwich compound, (η5-C5H5)2Ti(CH3)Cl, but the thermal stability is comparable.
- Erskine, Gordon J.,Hurst, Graham J. B.,Weinberg, Erica L.,Hunter, Brian K.,McCowan, James D.
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p. 265 - 270
(2007/10/02)
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- THE APPLICATION OF 13C AND 1H NMR SPECTROSCOPY TO THE INVESTIGATION OF THE DINITROGEN FIXATION PROCESS IN THE SYSTEM (η-C5H5)2TiCl2-Mg
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The N2 reduction reaction in the system (η-C5H5)2TiCl2-Mg in tetrahydrofuran was examined.The 13C and 1H NMR results as well as the chemical properties of the products formed revealed that the reaction yielded a mixture of compounds in which the titanium atom was bonded both to the μ-(η5: η5-fulvalene) ligand and to the cyclopentadienyl ligands.In this system dinitrogen undergoes reduction to N3-, which then forms M3N bridges (M = Ti, Mg).The nitride nitrogen may readily be oxidized to imide nitride N-1, which may react further, e.g. with carbon monoxideto produce isocyanates, or, with excess oxidizing agent N2.THF in this system undergoes polymerisation.In addition, a - OC4H9 alkoxy group is formed which makes the substitution of the cyclopentadienyl group bonded to the titanium atoms possible.
- Sobota, Piotr,Janas, Zofia
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- Cyclopentadienyldichlorotitanum(III): A Free-Radical-like REagent for Reducing -N=N- Multiple Bonds in Azo and Diazo Compounds
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Diphenyldiazomethane was reduced by (co = η5-C5H5) to a hydrazonido(2-) ligand to form , which loses and evolves to a dinuclear complex, , in which the two (cpTiCl) units are bridged by two hydrazonido(2-) ligands.Both hydrazonido ligands are η2-N,N' bonded to the same titanum atom in the solid state, with titanum-nitrogen bond distances ranging from 2.006(6) to 2.178(5) Angstroem, while the second titanum is bonded at very short distances to the terminal nitrogens only, 1.860(5) and 1.835(6) Angstroem.The 1H NMR spectrum at -64 deg C (CDCl3) is in agreement with the solid-state structure showing the nonequivalence of the two cp rings, which become equivalent at room temperature because of the stereochemical nonrigidity of the hydrazonido ligand. reacted with azobentene, forming a dimeric complex, , in which the phenylimido ligand forms from a -N=N- bend cleavage promoted by titanum(III).Phenylimido bridges the two titanum atoms at rather short distance Ti-N, 1.920(4) Angstroem, with nitrogen having sp2 geometry, so that a multiple Ti-N interaction is involved.The molecular complexity of , which may be a main point in determining its reactivity, was determined by X-ray analysis carried out on the solid isolated from THF solution, .It was found to be formed by the same number of pentacoordinate and tetracoordinate titanum(III) monomeric units.Crystallographic details for are as follows: space group P1/ (triclinic), a = 11.139(4), b = 13.641(5), c = 9.398(4) Angstroem, α = 95.31(3), β = 106.94(2), γ = 98.51(3) deg, V = 1337.0(9) Angstroem3, Dcalc = 1.451 g cm-3, Z = 2.The final R factor is 4.9percent for 2727 observed reflections.Crystallographic details for are as follows: space group P21/c (monoclinic), a = 18.704(2), b = 785(1), c = 21.049(2) Angstroem, β = 100.57(1) deg, V = 3400.0(6) Angstroem3, Dcalc = 1.339 g cm-3, Z = 4.The final R factor is 5.4percent for 2519 observed reflections.Crystallographic details for are as follows: space group C2/c (monoclinic), a = 14.041(2), b = 12.743(2), c = 15.875(3) Angstroem, β = 115.23(32) deg, V = 2569.5(8) Angstroem3, Dcalc = 1,474 g cm-3, Z = 4.The final R factor is 3.1percent for 1035 observed reflections.
- Gambarotta, S.,Floriani, C.,Chiesi-Villa, A.,Guastini, C.
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p. 7295 - 7301
(2007/10/02)
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- Ligation Studies of Titanium-Phenoxide and -Dimethylamide Derivatives with Covalent Metal Halides: a Route to Binuclear Transition-metal Complexes
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Convenient and high-yield syntheses for (Ti(cp)(OPh)3) and (Ti(cp)Cl(OPh)2) (cp=η-C5H5) are described.The donor characteristics of the mixed phenoxides (Ti(cp)n(OPh)(4-n)), n=0, 1, or 2, ((TiCl2(OPh)2)2), (Ti(cp)Cl(OPh)2), and of Ti(NMe2)4 have been investigated.Reactions with MCl3 (M=Ti, V, or Cr), VOCl3, MX4 (M=Ti, Zr, Hf, or Sn; X=Cl or Br), and MCl5 (M=Nb, Ta, or Mo) generally feature exchange of OPh and NMe2 groups with halide rather than complexation.In several instances, using appropriate reaction conditions, the solid adducts MX4Ti(NMe2)4 (M=Sn, X=CL or Br; M=Zr or Hf, X=Cl), SnCl4(Ti(cp)2(OPh)2), and ZrCl4Ti(OPh)4 have been isolated and fully characterised by analitycal and spectral data.
- Wade, Steven R.,Wallbridge, Malcolm G. H.,Willey, Gerald R.
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p. 271 - 274
(2007/10/02)
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- Complexation and Exchange Reactions of some Dimethylamino-substituted Group 4 Compounds
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Reactions of CH2(NMe2)2, (1), SiMe2(NMe2)2, (2), (cp=η-cyclopentadienyl), (3), and , (4), with covalent metal halides MCl4 (M=Ti,Zr,Si,Ge,or Sn) and MCl3 (M=Ti,V,or Cr) fall into two categories: (a) N-donor chelation leading to complex formation and (b) halide-NMe2 exchange.Compound (1) gives 1:1 complexes with MCl4 (M=Ti or Sn) and 2:1 complex with VCl3.Compound (2) provides 1:1 complexes with MCl4 (M=Ti,Zr,Hf, or Sn).The decomposition of TiCl4*SiMe2(NMe2)2 --> invariably occurs in both the solid state and solution.There is no reaction of (2) with metal(III) chlorides.With MCl4 (M=Si or Ge 'scrambling' reactions involving halide-NMe2 exchange occur and these have been monitored by 1H n.m.r. spectroscopy.Reactions of (3) and (4) with MCl4 (M=Si,Ge,Sn,Ti,Zr,or Hf) consistently feature halide-NMe2 exchange rather than adduct formation.All complexes have been characterised by analytical and spectroscopic (1H n.m.r. and i.r.) investigations.
- Wade, Steven R.,Willey, Gerald R.
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p. 1264 - 1267
(2007/10/02)
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- ON THE NATURE AND REACTIVITY OF Cp2TiCH3
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Reaction of Cp2TiCl with 1 eq. of CH3Li in ether at -78 deg C yields the green, thermally unstable, trivalent Ti compound Cp2TiCH3 * EPR studies on ether solutions of this compound reveal it to be present in solution as the adduct Cp2TiCH3 * OEt2 * By reaction with DCl Cp2TiCl2 and CH3D are formed.Reaction with 2,6 xylylisocyanide leads to insertion of the isocyanide into the Ti-CH3 bond, while reaction with CS2 yields the disproportionation products Cp2-Ti(CH3)2 and Cp2TiCS2.Thermal decomposition studies on deuteriated analogues confirm the Ti-CH3 structure.The ratedetermining step in the decomposition process is the abstraction of a Cp proton by the methyl group.Under nitrogen the decomposition reaction yields NH3 and N2H4 in amounts of up to 0.28 moles N/Ti.Some catalytic applications of Cp2TiCH3 for hydrogenation and isomerisation of olefins and acetylenes are briefly mentioned.
- Klei, E.,Teuben, J. H.
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