- TRI-1-METHALLYL- AND 1-METHALLYL-BUTADIENE GROUP IV TRANSITION METAL COMPLEXES
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Reaction of Cp'MCl3 (Cp' = η5-C5(CH3)5; M = Ti, Zr, Hf) with 2-butenylmagnesium bromide at low temperatures gives Cp'M(1-methallyl)3, which is readily converted into Cp'M(η3-1-methallyl)(η4-butadiene) on heating.Only Cp'Hf(1-methallyl)3 could be isolated; it is fluxional and its NMR and IR spectra indicate that it consists of a complex mixture of isomers containing interconverting η1- and η3-1-methallyl groups.The compounds Cp'M(η3-C4H7)(η4-C4H6) are much more thermally stable; they show fluxional behaviour, but this is limited to theη3-1-methallyl group.These complexes are very reactive towards a large variety of organic substrates.
- Blenkers, J.,Meijer, H. J. de Liefde,Teuben, J. H.
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- Facile functionalizations of permethyltitanocene dichloride to chiral persubstituted titanocene complexes
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The new class of compounds arising from unconventinal additions of 1, 4-disubstituted 1, 3-butadiynes to activated permethylmetallocene species of Ti and Zr can be used in facile functionalizations. For example, the chiral product 5, obtained from the addition of tBuC=CC=CtBu to activated permethyltitanocene, has been derivatized by simple means, e.g., hydrogen chloride, bromine, or dihydrogen, affording practically useful functionalized titanocene compounds containing a chiral auxiliary ligand with an intramolecularly coordinated (compound 7) or a free double bond (compounds 8a, b). The new complexes have been characterized spectroscopically. Additionally, X-ray crystal structure analyses were performed for 7 and 8a, b.
- Pellny, Paul-Michael,Burlakov, Vladimir V.,Baumann, Wolfgang,Spannenberg, Anke,Horá?ek, Michal,Stěpni?ka, Petr,Mach, Karel,Rosenthal, Uwe
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- Reactivity of functionalised decamethyltitanocenes: Synthesis and structure of chiral monocyclopentadienyl titanium halogenides
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The recently described unconventional substituted titanocene complex [Cpa -Ti{η5-C5Me3(CH 2-CH(tBu)-η2-C2-CH(tBu)-CH2)}] (1) can be derivatised by simple means (Br2, HX with X = Cl, Br) to generate the titanocene dihalogenides 2-Br, 2-Cl, which give in a subsequent reaction besides Cpa&-TiX3 (3-Br: X = Br, 3-Cl: X = Cl) the titanium complexes 4-Cl resp. 4-Br with one functionalised chiral cyclopentadienyl ligand. In the reaction of 1 with Et3N·3HF an analogous isostructural titanocene dihalogenide 2-F as well as the unusual dimeric anionic heptafluoride 5 are formed. All complexes have been characterised spectroscopically, and X-ray crystal structure determinations were performed for 4-Cl and 2-F.
- Burlakov, Vladimir V.,Lyssenko, Konstantin A.,Spannenberg, Anke,Baumann, Wolfgang,Arndt, Perdita,Shur, Vladimir B.,Rosenthal, Uwe
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- The Puzzling Monopentamethylcyclopentadienyltitanium(III) Dichloride Reagent: Structure and Properties
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Following the track of the useful titanocene [Ti(η5-C5H5)2Cl] reagent in organic synthesis, the related half-sandwich titanium(III) derivatives [Ti(η5-C5R5)Cl2] are receiving increasing attention in radical chemistry of many catalyzed transformations. However, the structure of the active titanium(III) species remains unknown in the literature. Herein, we describe the synthesis, crystal structure, and electronic structure of titanium(III) aggregates of composition [{Ti(η5-C5Me5)Cl2}n]. The thermolysis of [Ti(η5-C5Me5)Cl2Me] (1) in benzene or hexane at 180 °C results in the clean formation of [{Ti(η5-C5Me5)Cl(μ-Cl)}2] (2), methane, and ethene. The treatment of 1 with excess pinacolborane in hexane at 65 °C leads to a mixture of 2 and the paramagnetic trimer [{Ti(η5-C5Me5)(μ-Cl)2}3] (3). The X-ray crystal structures of compounds 2 and 3 show Ti-Ti distances of 3.267(1) and 3.219(12) ?, respectively. Computational studies (CASPT2//CASSCF and BS DFT methods) for dimer 2 reveal a singlet ground state and a relatively large singlet-triplet energy gap. Nuclear magnetic resonance spectroscopy of 2 in aromatic hydrocarbon solutions and DFT calculations for several [{Ti(η5-C5Me5)Cl2}n] aggregates are consistent with the existence of an equilibrium between the diamagnetic dimer [{Ti(η5-C5Me5)Cl(μ-Cl)}2] and a paramagnetic tetramer [{Ti(η5-C5Me5)(μ-Cl)2}4] in solution. In contrast, complex 2 readily dissolves in tetrahydrofuran to give a green-blue solution from which blue crystals of the mononuclear adduct [Ti(η5-C5Me5)Cl2(thf)] (4) were grown.
- García-Castro, María,García-Iriepa, Cristina,Del Horno, Estefanía,Martín, Avelino,Mena, Miguel,Pérez-Redondo, Adrián,Temprado, Manuel,Yélamos, Carlos
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- Reactions of Organotitanoxane Fluorides with AlR3 (R = Me, Et, CH2Ph) and Me3SiCl: X-ray Crystal Structures of [C5Me5Ti(μ-O)]4F[(μ-F)AlMe 3]3, [C5Me5Ti(μ-O)]4F 3[(μ-F)Al(CH2Ph)3]
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A new pentamethylcyclopentadienyl titanoxane fluoride (C5Me5)4Ti4O5F 2 (1b) has been synthesized from (C5-Me5)4Ti4O5Cl 2 using the fluorinating reagent Me3SnF. The fluorination of organotitanoxane chlorides proceeds via a proposed intermediate similar to the four-membered ring Ti(μ-Cl)(μ-F)Sn and the bridged Ti(μ-F)ClSnMe3 species. The reactions of 1b and [C5Me5Ti(μ-O)F]4 with AlR3 (R = Me, Et, CH2Ph) afforded the thermally unstable adducts [C5Me5Ti(μ-O)]4F 4-n[(μ-F)AlR3]n (n = 1-4), which proceed with selective exchange of fluorine atoms for alkyl groups to give an eight-membered alkylated ring compound [C5Me5Ti(μ-O)R]4. The reactions of 1b and [C5Me5Ti(μ-O)F]4 with Me3SiCl result in exchange of fluorine for chlorine atoms. Moreover, using an excess of Me3SiCl leads to a novel oxygen-chlorine exchange reaction to give C5Me5Ti(μ-O)]4F[(μ-F)AlMe 3]3 . The crystal structures of complexes (C5Me5)4Ti4O5X 2 (X = Cl (1a), F (1b)), [C5Me5Ti(μ-O)]4F[(μ-F)AlMe 3]3 (2b), [C5Me5Ti(μ-O)]4F 3[(μ-F)Al(CH2Ph)3] (3a), and [C5Me5Ti(μ-O)Et]4 (4) have been determined by X-ray diffraction studies, Both chlorides and fluorides in 1a and Ib, respectively, are oriented to the exo position of their butterfly structures. The bond lengths of the terminal fluorines (Ti-Ft) in compounds 2b and 3a are discussed with respect to the deviation from the bond lengths of the bridging fluorines (Ti-Fb-Al). The structure of 4 displays a nonplanar Ti4O4 ring conformation as shown in 2b and 3a.
- Yu, Peihua,Pape, Thomas,Uson, Isabel,Said, Musa A.,Roesky, Herbert W.,Montero, Mavis L.,Schmidt, Hans-Georg,Demsar, Alojz
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- (C5Me5)SiMe3 as a mild and effective reagent for transfer of the C5Me5 ring: an improved route to monopentamethylcyclopentadienyl trihalides of the group 4 elements
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The reaction between (C5Me5)SiMe3 and group 4 element tetrahalides MX4 (M=Ti, X=Cl, Br, I; M=Zr and Hf, X=Cl) gives the corresponding (η5-C5Me5)MX3 derivatives in nearly quantitative yields in a one-step procedure without the need for further purification.
- Llinas, Gerardo Hidalgo,Mena, Miguel,Palacios, Federico,Royo, Pascual,Serrano, Ricardo
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- Influence of ligands and cocatalyst on the activity in ethylene polymerization of soluble titanium complexes
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Known and new titanium complexes bearing alkoxy, phenoxy, carboxylate and cyclopentadienyl ligands in addition to chlorine have been tested towards ethylene polymerization after activation with aluminum alkyls (AlR3) or methylalumoxane (MAO). In the absence of cyclopentadienyl ligands the optimal productivity obtained is very similar either with AlR3 or MAO, but higher MAO/Ti than AlR3/Ti ratios are necessary. In the case of complexes with the Cp ligand much better productivity can be obtained with high MAO ratios thus confirming that under these conditions a different activation mechanism is operative.
- Conti, Giuseppe,Arribas, Guillermo,Altomare, Angelina,Ciardelli, Francesco
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- Cleavage of Dinitrogen from Forming Gas by a Titanium Molecular System under Ambient Conditions
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Simple exposure of a hexane solution of [TiCp*Me3] (Cp=η5-C5Me5) to an atmosphere of commercially available and inexpensive forming gas (H2/N2 mixture, 13.5–16.5 % of H2) at room temperature leads to the methylidene–methylidyne–nitrido cube-type complex [(TiCp*)4(μ3-CH)(μ3-CH2)(μ3-N)2] via dinitrogen cleavage. This paramagnetic compound reacts with [D1]chloroform to give the titanium(IV) methylidyne–nitrido species [(TiCp*)4(μ3-CH)2(μ3-N)2], whereas its one-electron oxidation with AgOTf or [Fe(η5-C5H5)2](OTf) (OTf=O3SCF3) yields the diamagnetic ionic derivative [(TiCp*)4(μ3-CH)(μ3-CH2)(μ3-N)2](OTf). The μ3-nitrido ligands of the methylidyne–nitrido cubane complex can be protonated with [LutH](OTf) (Lut=2,6-lutidine) or hydrogenated with NH3?BH3 to afford μ3-NH imido moieties.
- González-Moreiras, Mariano,Mena, Miguel,Pérez-Redondo, Adrián,Yélamos, Carlos
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supporting information
p. 3558 - 3561
(2017/03/20)
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- Highly efficient one-step direct synthesis of monocyclopentadienyltitanium complexes
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This report describes a highly efficient one-step synthetic strategy for monocyclopentadienyltitanium complexes by the direct reaction of TiCl 4 with substituted cyclopentadienes, without adding any other reagents. This new synthetic method is particularly efficient for cyclopentadienes with a pendant group that can bond or coordinate to the Ti atom.
- Zhang, Yuetao,Mu, Ying
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p. 631 - 634
(2008/10/09)
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- New titanatranes: Characterization and styrene polymerization behavior
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New titanatranes containing cyclopentadienyl ligands were prepared by the reactions of various kinds of trialkanolamines with (C5Me4R)TiCl3 (Cp′ = C5Me4R) in the presence of triethylamine. The X-ray analyses reveal that they exist in the monomeric form in the solid state and the Ti atom adopts essentially an η5 bonding posture with the Cp′ ring and a tetradentate bonding mode with the trialkanolatoamine ligand via a transannular interaction from the bridgehead N atom to Ti. All compounds show very high catalytic activity for the syndiospecific polymerization of styrene in the presence of modified methylaluminoxane (MMAO) cocatalyst.
- Kim, Youngjo,Han, Yonggyu,Hwang, Jeong-Wook,Kim, Myong Woon,Do, Youngkyu
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p. 1127 - 1135
(2008/10/08)
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- Synthesis and characterization of new alkoxide and aryloxide derivatives of titanium and zirconium. X-ray molecular structure of
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Lithium or sodium alkoxides MOR (R = CH2CH-CMe2; M = Li 1; Na 2; R = C6F5; M = Li 3) were prepared by reaction of the alcohols with n-butyl lithium or sodium metal in hexane.Reaction of a hexane suspension of 3 with SiClMe3 afforded SiMe3(OC6F5) 4, whereas the reaction of 3 equivalents of C6F5OH with AlMe3 in hexane led to Al(OC6F5)3 5.Compounds 1 or 2 react with one equivalent of *Cl2Me> (Cp* = C5Me5) in toluene to give *ClMe(OCH2CH=CMe2)> 6.Complex 6 reacts with AlEtCl2 to give quantitatively *Cl3>.In the presence of water, the hydrolysis of 6 takes place giving the μ-oxo compound *Cl)(μ-O)>3>. *Cl2Me> reacted with an excess of the alcohol C6F5OH to give *(OC6F5)3> 7. reacted with two equivalents of pentafluorophenol in the presence of aniline to give the dialkoxide 8.When the same reaction was carried out in a 1:1 molar ratio, a mixture of 8 and the chloroalkoxide 9 was obtained.A clean reaction takes place when the μ-oxo compound is treated with two equivalents of pentafluorophenol, leading to the isolation of the alkoxo complex 2(μ-O)> 10.The methylalkoxo derivative 11, was obtained by reaction of with one equivalent of 3.Alternative methods can also be followed to synthesize 8 and 11.The crystal and molecular structure of 8 has been determined by X-ray diffraction methods.The most interesting feature of this structure is the disposition of the (C6F5) ring planes, which are located practically on the reflection plane defined by O(1), Zr(1) and O(1)'. Keywords: Titanium; Zirconium; Alkoxides; X-ray diffraction; Group 4; Cyclopentadienyl
- Amor, J. I.,Burton, N.C.,Cuenca, T.,Gomez-Sal, P.,Royo, P.
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p. 153 - 160
(2007/10/02)
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- Facile Reduction of Organometallic Halides with Bis(pentamethylcyclopentadienyl)ytterbium and the X-Ray Structure of (C5Me5)2YbCl(THF)
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Reduction of (C5H5)2MCl2 (M=Ti, Zr) and TiCl4 with one equiv. of (C5Me5)2Yb(THF)2 gave rise to the formation of 2 and TiCl3(THF)3, respectively, together with (C5Me5)2YbCl(THF).The molecular structure of (C5Me5)2YbCl(THF) has been determined by the X-ray analysis.The reaction of (C5Me5)2Yb(THF)2 with Me3SiCl yielded a mixture composed of n and C5Me5(CH2)4OSiMe3.
- Yasuda, Hajime,Yamamoto, Hitoshi,Yokota, Kiyohiko,Nakamura, Akira
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p. 1309 - 1312
(2007/10/02)
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- Structural features in electron-deficient (η-pentamethylcyclopentadienyl)titanium-diene complexes and their catalysis in the selective oligomerization of conjugated dienes
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A series of titanium-diene complexes of the type TiX(C5Me5)(s-cis-diene) (X = Cl, Br, I) was synthesized by the stoichiometric reaction of TiX3(C5Me5) with (2-butene-1,4-diyl)magnesium derivatives or by the reaction of TiX3(C5Me5) with RMgX (R = i-Pr, t-Bu, Et; X = Cl, Br, I) in the presence of a conjugated diene. All complexes were isolated as highly air-sensitive blue crystals in 30-60% yields. The complexes of unsubstituted and C(1) and/or C(4) alkyl-substitutecl dienes (butadiene, 1,3-pentadiene, 1,4-diphenylbutadiene) exhibit unique prone (endo) conformation while the complexes of C(2) and/or C(3) alkyl-substituted dienes (isoprene, 2,3-dimethylbutadiene, 2,3-diphenylbutadiene) prefer the supine (exo) conformation as revealed by the 1H and 13C NMR spectroscopic together with the X-ray diffraction analyses. The indirect 13C-13C coupling constants prove the pronounced η4-diene metal bonding nature for the prone titanium-diene complexes and substantial participation of bent metallacyclo-3-pentene structure for the supine complexes. TiCl(C5Me5)(s-cis-C4H6) of prone geometry crystallizes in space group P21/c with a = 6.999 (1) A?, b = 14.625 (3) A?, c = 13.842 (2) A?, β = 95.61 (2)°, and Z = 4. TiCl(C5Me5)(s-cis-1,4-diphenylbutadiene) belongs to orthorhombic space group Pnma with a = 8.260 (1) A?, b = 16.395 (3) A?, c = 16.308 (3) A?, and Z = 4. TiCl(C5Me5)(s-cis-2,3-diphenylbutadiene) of supine geometry crystallizes in space group C2/c with a = 22.049 (3) A?, b = 8.107 (2) A?, c = 26.869 (4) A?, β = 110.11 (1)°, and Z = 8. The extended Hu?ckel molecular orbital calculations reveal that the prone and supine structures of TiCl-(C5Me5)(C4H6) are energetically very close to each other. The nature of Ti-C4H6 bonding is discussed on the basis of population analysis. A low-valent species Ti(C5Me5)(isoprene) (g = 1.999 in EPR) generated by the reduction of TiCl(C5Me5)(isoprene) or on treatment of TiCl2(C5Me5) with (enediyl)magnesium catalyzes a highly selective (>99%) tail-to-head linear dimerization of isoprene and 2,3-dimethylbutadiene.
- Yamamoto, Hitoshi,Yasuda, Hajime,Tatsumi, Kazuyuki,Lee, Keonil,Nakamura, Akira,Chen, Jie,Kai, Yasushi,Kasai, Nobutami
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p. 105 - 119
(2008/10/08)
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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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- Preparation of Titanium Pentamethylcyclopentadienyl Trialkyls and Crystal Structure of Tribenzylpentamethylcyclopentadienyltitanium, showing Some Evidence of a CH2...Ti Interaction
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Titanium pentamethylcyclopentadienyl trialkyls (η5-C5Me5)TiR3 (R = Me, CH2SiMe3, C6F5, and CH2Ph) are easily obtained by conventional alkylation of the trichloro analogue; the structure of the tribenzyl derivative, determined by X-ray methods, shows some evidence of CH2...Ti interaction.
- Mena, Miguel,Pellinghelli, Maria Angela,Royo, Pascual,Serrano, Ricardo,Tripicchio, Antonio
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p. 1118 - 1119
(2007/10/02)
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- Preparation, structure, and reactivity of a (pentamethylcyclopentadienyl)titanium dimer bridged by oxygen and tetramethylmethylenecyclopentadienyl
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The reaction between Cp*2Ti (Cp* = η5-C5(CH3)5) and N2O in toluene affords [(Cp*Ti)2-μ-(η1:η5-C 5(CH3)4CH2)(μ-O)2] (I). The structure of the product was determined by X-ray diffraction; it crystallizes in the orthorhombic space group Pnma with a = 10.650 (5) A?, b = 15.283 (3) A?, c = 17.064 (8) A?, and Z = 4. The structure was refined to R = 0.048 and Rw = 0.052 for 256 parameters and 1226 observed reflections. The molecule consists of two (η5-C5(CH3)5)Ti units bridged unsymmetrically by two oxygen atoms (Ti(1)-O = 1.961 (3) A? and Ti(2)-O = 1.787 (3) A?) and an η1:η5-C5(CH3) 4CH2 ligand (η1 to Ti(2) and η5 to Ti(1)). The bond distances are in agreement with the description of the C5(CH3)4CH2 bridge as a truly methylenic η1:η5 ligand and not as an η2:η4 olefinic ligand. The Ti(2)-CH2 distance is 2.178 (6) A?; all other C-C and Ti-C distances are normal for Cp*Ti units. The methylenic description of C5(CH3)4CH2 is supported by NMR (δ(CH2) 50.4 in the 13C spectrum) and IR (ν(C-H) 2960, 2900, and 2850 cm-1) spectroscopies and also explains the remarkable stability of I (no reaction with H2, CO, or C2H4) since both titanium atoms are Ti(IV). With HCl, I gives Cp*2TiCl2 and Cp*TiCl3.
- Bottomley, Frank,Egharevba, Gabriel O.,Lin, Ivan J. B.,White, Peter S.
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p. 550 - 553
(2008/10/08)
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