Reaction Of TiCl4 Research Articles

Titanium and zirconium benzofuranoxides. Crystal structures and catalytic properties

Reactions of Ti(OiPr)4 or Zr(OEt)4 with 4 equivalents of 2,3-dihydro-2,2-dimethyl-7-benzofuranol (ddbfoH) in toluene gave neutral complexes that in the solid state are dimers of [Ti(micro-ddbfo)2(ddbfo)6] and [Zr(ddbfo)3(EtOH)(micro-EtO)]2 composition. The former could also be conveniently synthesized in a direct reaction of TiCl4 with ddbfoH. This air-stable aryloxo compound was found to initiate living ring-opening polymerization of lactides affording polyesters with narrow molecular weight distribution. It also catalyzed addition of terminal acetylenes to aryl aldehydes.

The Effect of Film Thickness on the Suitability of Titanium Oxynitride (TiNxOy, x + y = 1) Films as Heat Mirrors – Formed by the Atmospheric Pressure CVD of TiCl4 and NH3

AbstractFilms of titanium oxynitride are assessed for their potential as heat mirror coatings on window glass, as a function of the film thickness. The coatings are deposited from the atmospheric pressure (AP) chemical vapor reaction of TiCl4 and ammonia. The heat mirror properties are evaluated using transmission and reflection spectroscopy. The composition of the samples is determined by X‐ray photoelectron spectroscopy (XPS), and the thickness of the films by scanning electron microscopy (SEM). These results suggest that an effective heat mirror can be formed by a 100 nm thick coating of titanium oxynitride, which has a transmission of 49 % in the visible (610 nm), and a reflection of 46 % in the near infrared (1320 nm).

Ziegler-Natta catalytic systems

A calorimetric investigation on the reactions of TiCl4 with phthalates in 1,1,2,2-tetrachloroethane (TCE) is presented in order to better understand the complex interactions present in Ziegler-Natta catalytic systems. The Lewis bases diethyl isophthalate (L1), diethyl terephthalate (L2) and the ortho-isomer diethylphthalate (L3), have been chosen to study how the substituent positions could influence the energy and the stoichiometry of the complexation reactions.

CVD Reactions of TiCl4 with Ammonia: a Quantum Chemical Study

AbstractBased on density functional calculations, the mechanism and the energetic course of the chemical vapor deposition (CVD) reaction of TiCl4 with NH3 were studied at the level of B3LYP with 6‐311g(d) basis set. Furthermore, the polymerization processes of dimerization, trimerization and tetramerization were investigated. The calculation results indicate that the formation of polymers is favored at the elimination reaction. On the basis of the calculated energetics, a possible mechanism of the reduction reaction has been proposed.

Nanocrystalline anatase TiO2 photocatalysts prepared via a facile low temperature nonhydrolytic sol–gel reaction of TiCl4 and benzyl alcohol

Nanocrystalline anatase TiO2 photocatalysts prepared by a facile nonhydrolytic sol–gel (NSG) reaction of TiCl4 and benzyl alcohol at low temperature, followed by subsequent calcination at elevated temperatures were investigated in relation to their performance in the photocatalytic degradation of phenol. A variety of techniques including N2 adsorption, X-ray powder diffraction (XRD), diffuse reflectance FTIR spectroscopy (DRIFTS), thermogravimetric measurements (TG/DTA), transmission electron micrographs (TEM), and X-ray photoelectron spectroscopy (XPS) were employed to characterize the resulting materials. It is shown that the fresh nanocrystalline TiO2 sample obtained by the low temperature NSG process exhibits considerable activity comparable to that of commercial photocatalyst Degussa P-25, although evidence shows it to be surface-capped with appreciable amount of organic moieties. Moreover, it is demonstrated that the catalytic efficiency of the as-prepared nanocrystalline TiO2 sample can be further markedly enhanced by subsequent thermal treatment at elevated temperatures ranging from 300 to 600°C. Both the calcination temperature and calcination time appear to be crucial factors in influencing a number of critical properties of the calcined TiO2 samples such as the surface area, particle size, crystallinity, amount of surface hydroxyl groups, as well as carbonaceous residues. The TiO2 photocatalyst obtained by calcination at 400°C for 3h exhibits the highest activity toward photocatalytic degradation of phenol.

Thio- and seleno-ether complexes with Group 4 tetrahalides and tin tetrachloride: preparation and use in CVD for metal chalcogenide films

Reaction of TiCl(4) or ZrI(4) with the soft, neutral o-C(6)H(4)(CH(2)EMe)(2) (E = S or Se) in anhydrous CH(2)Cl(2) (or toluene) yields the distorted octahedral chelate complexes [MX(4){o-C(6)H(4)(CH(2)EMe)(2)}]. Using Et(2)Se gives [MX(4)(Et(2)Se)(2)] (M = Zr, X = Cl or I; M = Hf, X = I). The Sn(IV) analogues, [SnCl(4){o-C(6)H(4)(CH(2)EMe)(2)}] and [SnCl(4)(Et(2)Se)(2)] were obtained similarly. These complexes have been characterised spectroscopically and analytically, and crystal structures of trans-[SnCl(4)(Et(2)Se)(2)] and some selenonium salts derived as minor by-products from the parent Group 4 complexes are described. The neutral chalcogenoether complexes have been evaluated as single source precursors to ME(2)/ME thin films via LPCVD. [TiCl(4){o-C(6)H(4)(CH(2)EMe)(2)}] leads to the deposition of air and moisture stable TiE(2) films (with no residual Cl). Coverage of the substrate is uniform with platelet growth perpendicular to the surface. The heavier Zr(IV) species do not lead to significant ZrE(2) deposition. On the other hand, LPCVD of [SnCl(4){o-C(6)H(4)(CH(2)SMe)(2)}] leads to deposition of SnS(2) at lower temperatures and SnS at higher temperatures, while [SnCl(4){o-C(6)H(4)(CH(2)SeMe)(2)}] gives rather uneven coatings of SnSe(2). The Et(2)Se derivative, [SnCl(4)(Et(2)Se)(2)] leads to uniform deposition of SnSe(2) with growth perpendicular to the substrate surface. The SnE(2)/SnE films are stable indefinitely to air and moisture. The generation of TiS(2), SnS(2) and SnS in this way are very rare examples of metal sulfide deposition from C-S bond fission within a thioether complex.

TiN/SiN x submicronic multilayer coatings obtained by chemical vapor deposition in a fluidized bed reactor at atmospheric pressure (AP/FBR-CVD)

TiN/SiN x multilayer coatings were deposited on stainless steel by Chemical Vapor Deposition in a Fluidized Bed Reactor at Atmospheric Pressure (AP/FBR-CVD) by reaction of TiCl 4 and SiCl 4 with NH 3 at 850 °C. Due to the immiscibility of crystalline TiN and amorphous SiN x , interdiffusion between layers is avoided even at the high working temperature. The thickness of the individual layer was in the nanometer range. Coatings were characterized by means of SEM, TEM, GD-OES, SIMS, XRD and nanoindentation. A mechanism for the growth rate and diffusion of Ti and Si into the steel is discussed.

Fundamental study on magnesiothermic reduction of titanium dichloride

With the purpose of establishing a high speed and (semi-)continuous process for the production of high-purity titanium, a fundamental study on the magnesiothermic reduction of titanium dichloride (TiCl2) using a titanium reaction container was investigated. TiCl2 was synthesized by the reaction of TiCl3 with metallic titanium and used as feed material in metallothermic reduction. The obtained TiCl2 and the magnesium reductant were placed in a titanium reaction container and heated at a rate of 0.056 K/s (3.3 K/min) in a stainless-steel chamber filled with argon gas. The sample temperature increased rapidly above 973 K, and the magnesiothermic reduction of TiCl2 proceeded at a high speed. After the reduction, the reaction product—magnesium chloride (MgCl2)—and the excess magnesium were removed by leaching or vacuum distillation. Under certain conditions, titanium with 99.7 pct purity was successfully obtained. The titanium reaction container showed no signs of damage, thereby indicating that it is suitable for use in the magnesiothermic reduction of TiCl2.

Formation of 4H‐Azepine by the Electrophilic Reaction of a 2‐Methoxyazepinium Ion and Analysis of the Sigmatropic Isomerization

Abstract2‐Aryl‐2H‐, 3‐aryl‐3H‐, and 4‐aryl‐4H‐azepine were formed by the novel, electrophilic, πLUMO‐controlled reaction of the 2‐methoxyazepinium ion, generated in situ by the reaction of TiCl4 with 2,7‐dialkoxy‐2H‐azepine and an aryl compound, for which the kinetic parameters of the sigmatropic hydrogen rearrangement of the 4H‐azepine was measured. The substitution and hydrogen shift of the azepinium ion were analyzed with DFT studies. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Synthesis and characterisation of titanium pyridine- and pyrimidine-thiolates and their application as precursors to titanium disulfide

The reaction of TiCl 4 with pyridine- and pyrimidine-thiol has been investigated. Reaction of TiCl 4 with 3 equiv. of 2-mercaptopyridine and 3 equiv. of tert-butylpyridine in toluene at room temperature resulted in the formation of the tris(pyridine-2-thiolate) complex [TiCl(SC 5H 4N) 3] ( 1). The related reaction between TiCl 4 with 3 equiv. of 2-mercaptopyrimidine and 3 equiv. of tert-butylpyridine in toluene at room temperature resulted in the isolation of the complex [TiCl(SC 4H 3N 2) 3] ( 2). Compound 2 has been characterised by X-ray crystallography. Low pressure CVD of 1 and 2 produced brown/gold films of TiS 2/TiO 2 on glass substrates at 550 and 600 °C.

Ethylene/1-hexene copolymerization with TiCl 4/MgCl 2/AlCl 3 catalyst in the presence of hydrogen

A TiCl 4/AlCl 3/MgCl 2 (Cat-B) catalyst containing 5.2 wt.% Al was prepared by the reaction of TiCl 4 with ethanol adduct of AlCl 3/MgCl 2 mixture. A TiCl 4/MgCl 2 catalyst (Cat-A) without doped AlCl 3 was also prepared by the same method. Ethylene-1-hexene copolymerization catalyzed by Cat-B in the presence of hydrogen showed slightly higher efficiency and higher 1-hexene incorporation than Cat-A. Comonomer incorporation was markedly increased when the cocatalyst AlEt 3 was replaced by Al( i-Bu) 3. Adding Ph 2Si(OMe) 2 as external donor in the catalyst system caused decrease in polymerization activity and 1-hexene incorporation. Each copolymer sample was fractionated into three fractions: n-heptane insoluble fraction (fraction A), n-heptane soluble and n-hexane insoluble fraction (fraction B) and n-hexane soluble fraction (fraction C). In most cases the amount of intermediate fraction (fraction B) was smaller than the other fractions and did not increase as the total 1-hexene content increase, indicating the presence of two classes of copolymer fractions with greatly different comonomer content and clear bimodality of the copolymer composition distribution. Doping AlCl 3 in the catalyst, changing cocatalyst and adding external donor mainly changed the weight ratio of fraction A to fraction C, but exerted little influences on their composition. According to the sequence distribution data of the fractions, doping AlCl 3 in the catalyst resulted in slight decrease of product of reactivity ratios ( r 1 r 2) in both fraction A and fraction C.

Constrained geometry tetramethylcyclopentadienyl-phenoxy titanium complexes: Synthesis, structures and catalytic properties for ethylene polymerization

The synthesis of a new bidentate ligand, 1-(2-methoxyphenyl)-2,3,4,5-tetramethyl-cyclopentadiene ( 1), as well as its corresponding constrained geometry titanium complex, 2-tetramethylcyclopentadienyl-phenoxytitanium dichloride [(TCP)TiCl 2, 2], was described. Complex 2 was synthesized by reaction of TiCl 4 with the lithium salt of 1, followed by CH 3Cl elimination at 65 °C. Molecular structures of 2 and a known complex, 2-tetramethylcyclopentadienyl-6-methyl-phenoxytitanium dichloride [(TCMP)TiCl 2, IVd], were determined by single-crystal X-ray diffraction. The Cp(cent)–Ti–O angles of 107.4° for 2, 107.0° for IVd reveal their sterically open features as catalyst precursors. When activated with Al i Bu 3 and Ph 3 C + B ( C 6 F 5 ) 4 - , complex 2 exhibits reasonable catalytic activity for ethylene polymerization, producing polyethylenes with moderate molecular weights and melting points.

TiSiN nanocomposite coatings by chemical vapor deposition in a fluidized bed reactor at atmospheric pressure (AP/FBR-CVD)

TiSiN nanocomposite coatings were deposited on stainless steel by chemical vapor deposition in a fluidized bed reactor at atmospheric pressure (AP/FBR-CVD) by reaction of TiCl4 and SiCl4 with NH3 at 850 °C. Coatings were characterized by means of GD-OES, XPS and XRD. TiSiN coatings with a Si content of 9 at.% showed a hardness of 28 GPa (the hardness of TiN and SiNx coatings was around 21 GPa) and a lower oxidation rate under dry air at 600 °C. Our results show for the first time that AP/FBR-CVD can be tuned for the deposition of nanocomposite ceramic coatings.

Titanium Complexes of Dialkanolamine Ligands: Synthesis and Structure

AbstractSynthesis of the title compounds, viz. [RN(CH2CH2O)(CHR1CR2R3O)]Ti(OiPr)2 (13–15) and [RN(CH2CH2O)(CHR1CR2R3O)]2Ti (18–28), by the reaction of one ortwo equivalents of the corresponding dialkanolamines RN(CH2CH2OH)(CHR1CR2R3OH) (1–12) with Ti(OiPr)4 is reported. Other routes to [RN(CH2CH2O)(CHR1CR2R3O)]2Ti, such as the reaction of Ti(CH2Ph)4 with dialkanolamine and the reaction of TiCl4(THF)2 with dialkanolamine/Et3N were also tested. Dimeric titanocane 16, [PhCH2N(CH2CH2O)2Ti(OMe)2]2, was obtained from the reaction of one equivalentof dialkanolamine 3 with CpTi(OMe)3. PhCH2N(CH2CH2O)2Ti(OMenth)2 (17) was prepared from the transalkoxylation reaction of 15 with two equivalents of menthol. The composition and structures of all novel compounds were established by 1H and 13C NMR spectroscopy as well as elemental analysis data. The possible solution structure features of 13–28 are discussed. The single‐crystal X‐ray diffraction study oftitanocane 16 clearly indicates a dimeric structure for this compound in the solid state. According to X‐ray data, compounds [PhCH2N(CH2CH2O)2]2Ti (19), [MeN(CH2CH2O)(CH2CHPhO)]2Ti (20), [MeN(CH2CH2O)(CH2CPh2O)]2Ti (23), erythro‐[MeN(CH2CH2O)(CHPhCHPhO)]2Ti (24), threo‐[MeN(CH2CH2O)(CHPhCHPhO)]2Ti (25), and {MeN(CH2CH2O)[CH(CH2)4CHO]}2Ti (27) possess a monomeric structure with a hexacoordinate titanium atom in the solid state. Among them complexes 19, 20, 23, 25, and 27 are characterized by a cis disposition of the nitrogen atoms in the coordination environment of the Ti atom, while nitrogen atoms in 24 occupy trans positions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Molecular engineering of coordination pockets in chloro-tris-phenoxo complexes of titanium(IV)

The chloro-tris-phenoxo complexes [TiCl(OAr) 3] (OAr = OC 6H 4CMe 3-4 ( 1), OC 6H 3Me 2-2,4 ( 2), OC 6H 2Me 3-2,4,6 ( 4), OC 6H 3(CHMe 2) 2-2,6 ( 5), OC 6H 3(CMe 3) 2-2,4 ( 6) and OC 6H 4Ph-2 ( 8) are prepared by heating 3 equivalents of the phenol and [TiCl 4] in toluene. X-ray crystal structure determinations show that 2 is a phenoxy-bridged dimer with the ortho-methyl groups making the beginning of a pocket about the terminal chloro ligand and 6 is a tetrahedral monomer in which the pocket is more well developed by the ortho- tert-butyl groups. Both 2 and 6 react with dmbipy to give [TiCl(OAr) 3(dmbipy)] [OAr = OC 6H 3Me 2-2,4 ( 3) and OC 6H 3(CMe 3) 2-2,4 ( 7)] in which the original pocket is destroyed. Reaction of TiCl 4 with 3 equivalents of LiOC 6H 4Ph-2 in diethyl ether gives [TiCl(OC 6H 4Ph-2) 3(diethyl ether)] ( 9) for which an X-ray crystal structure determination shows a trigonal bipyramidal coordination geometry with the diethyl ether lying trans to the chloro ligand. The three phenoxide ligands make up the equatorial plane which takes the 2-phenyl substituent on each phenoxo ligand away from the chloro ligand resulting in a partially collapsed cavity. The tied-back analogues of 2 and 6, [TiCl{(OC 6H 2Me 2-2,4-CH 2-6) 3N}] ( 11) and [TiCl({OC 6H 2(CMe 3) 2-2,4-CH 2-6} 3N)] · diethyl ether ( 12), are prepared by adding (HOArCH 2) 3N [Ar = C 6H 2Me 2-2,4 and C 6H 2(CMe 3) 2 2,4] to [TiCl(OCHMe 2) 3] in diethyl ether. An X-ray crystal structure of 12 showed a trigonal bipyramidal structure with a coordination environment about the terminal chloro ligand similar to that found in 6. Complex 12 reacts with pyridine to form the 6-coordinate complex [TiCl({OC 6H 2(CMe 3) 2-2,4-CH 2-6} 3N)(py)] ( 13).

Highly Efficient One-Step Direct Synthesis of Monocyclopentadienyltitanium Complexes

This report describes a highly efficient one-step synthetic strategy for monocyclopentadienyltitanium complexes by the direct reaction of TiCl4 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.

Milling and Additive Effects on Hydrogen Desorption Reactions of Li-N-H and Li-Mg-N-H Hydrogen Storage Systems

ABSTRACTHydrogen desorption reactions of the mixtures of (i) lithium amide and lithium hydride (LiNH2/LiH), and (ii) magnesium amide and lithium hydride (Mg(NH2)2/4LiH) were studied. Titanium compounds and nano-particles including fullerene (C60), were doped to those hydrogen storage mixtures respectively. The hydrogen desorption reactions were monitored by means of temperature programmed desorption (TPD) technique under an Ar atmosphere. The reaction of LiNH2/LiH was accelerated by adding either 1 mol% of Ti species or 0.2 mol% of fullerene (C60), while those additives did not show significant acceleration effects on the reaction of Mg(NH2)2/4LiH. Kinetic studies revealed the enhanced hydrogen desorption reaction rate constant for TiCl3 doped LiNH2/LiH, k = 3.1 × 10−4 s−1 at 493 K, and the prolonged ball-milling further improved reaction rate, k = 1.1 × 10−3 s−1 at the same temperature. For the dehydrogenation reaction of TiCl3 doped LiNH2/LiH, the activation energies estimated by Kissinger plot (95 kJ mol−1) and Arrhenius plot (110 kJ mol−1) were in reasonable agreement each other. The LiNH2/LiH mixture without additive exhibited slower hydrogen desorption process and the kinetic traces deviated from single exponential behavior. The results indicated the Ti(III) additives change the hydrogen desorption reaction mechanism of LiNH2/LiH.

Titanium complexes with novel triaryl-substituted phosphinimide ligands: Synthesis, structure and ethylene polymerization behavior

A series of titanium phosphinimide complexes [Ph 2P(2-RO-C 6H 4)] 2TiCl 2 ( 7, R = CH 3; 8, R = CHMe 2) and [PhP(2-Me 2CHO–C 6H 4)][THF]TiCl 3 ( 9) have been prepared by reaction of TiCl 4 with the corresponding phosphinimines under dehalosilylation. The structure of complex 9 has been determined by X-ray crystallography, and a solvent molecule THF was found to be coordinated with the central metal and the Ti–O bond was consistent with the normal Ti–O (donor) bond length. The complexes 7 and 8 displayed inactive to ethylene polymerization, and the complex 9 displayed moderate activity in the presence of modified methylaluminoxane (MMAO) or i-Bu 3Al/Ph 3CB(C 6F 5) 4, and this should be partly attributed to coordination of THF with titanium and the steric effect of two iso-propoxyl. And catalytic activity up to 32.2 kg-PE/(mol-Ti h bar) was observed.

Triphenyltin hydroxide as a precursor for the synthesis of nanosized tin‐doped TiO2 photocatalysts

Abstract1H and 119Sn NMR results indicate that, when Ph3SnOH is dissolved in CD2Cl2, it dehydrates to (Ph3Sn)2O, only a small amount of Ph3SnOH remaining in equilibrium at room temperature. As a result, the reaction of TiCl4 with Ph3SnOH in CH2Cl2 proceeds via hydrolysis of the halide to precipitate amorphous TiO2 that contains adsorbed organotin species. Calcination of the amorphous precursor to 723 K yields nanoparticles of tin‐doped TiO2 photocatalysts, that contain anatase and rutile phases, and may also contain a segregated SnO2 phase. The reaction conditions that lead to the formation of a SnO2 phase have been studied and we have found that it is formed when the amorphous precipitate is not thoroughly washed with CH2Cl2 or when non‐recrystallized commercial Ph3SnOH is used as a starting material. The catalysts obtained have a high activity for the photooxidation of toluene in the gas phase. In particular, a material obtained from non‐recrystallized Ph3SnOH is particularly promising because the toluene photooxidation rate is more than twice as high as when using Degussa P25. Copyright © 2005 John Wiley & Sons, Ltd.

Chiral Bis(η5:η1-pentafulvene)titanium Complexes

The series of bis(pentafulvene)titanium complexes (η6-C5H4CR2)2Ti (CR2 = C(p-tol)2 (3), adamantyl (4)) and their corresponding bis(benzofulvene) derivatives (η6-C9H6CR2)2Ti (CR2 = C(p-tol)2 (7), adamantyl (8)) have been synthesized by reaction of TiCl3·3THF with the pentafulvene ligands (2 equiv) and magnesium as reducing agent (1.5 equiv). The bis(fulvene) complexes 7 and 8 have been obtained as diastereomerically pure compounds. All complexes have been characterized by spectroscopy and by single-crystal X-ray diffraction. The bonding situation is best described as a π-η5:σ-η1 coordination mode. The bis(fulvene) complex 3 is approximately C2 symmetric, whereas 7 crystallizes as a conglomerate in the monoclinic space group P21 and one of the enantiomers was identified as a (S,pS,pR) stereoisomer showing C1 symmetry. The adamantyl benzofulvene complex 8 crystallizes in the monoclinic space group P21/c; both benzofulvene ligands are coordinated as optical antipodes, and a (S,pS,pR)/(R,pR,pS) configuration i...