Search results for "Titani"

Surface Chemistry Directs the Tunable Assembly of TiO 2 Anatase Nanocubes into Three‐Dimensional Mesocrystals

2019

Expanding the Size of Catecholesters - Modified Ligands for the Hierarchical Assembly of Dinuclear Titanium(IV) Helicates

2015

Five 2,3-dihydroxybenzoic acid derivatives 1 – 5 were used as starting materials to obtain the corresponding methyl and ethyl esters. Those were applied as ligands in the hierarchical self-assembly of lithium-bridged dinuclear titanium(IV) complexes 1a–4a, 1b–3b, and 5b. The equilibria between the mononuclear triscatecholate complexes (monomer) and the dinuclear helicates (dimer) were observed by 1H NMR spectroscopy in [D6]DMSO and [D4]MeOH at room temperature.

Herstellung von 1,5‐Cyclooctadiin und 1,3,5,7‐Cyclooctatetraen aus 1,5‐Cyclooctadien

1994

Preparation of 1,5-Cyclooctadiyne and 1,3,5,7-Cyclooctatetraene from 1,5-Cyclooctadiene Bromination of 1,5-cyclooctadiene (1) and stepwise dehydro-bromination first with KOtBu and then with KOtBu/18-crown-6 yields 1,5-cyclooctadiyne (5). A prolonged interaction of the base causes a complete transformation to cyclooc-tatetraene (6). Diyne 5 and even more the intermediate enyne 4 are highly reactive dienophiles. The cycloadducts 10–14 formed with 1,3-cyclohexadiene, carbon disulfide, and tetraphenylcyclopentadienone were isolated and characterized. Treatment of 5 with titanium tetrachloride induces a vigorous polymerization.

Stable Methylene- and Oxo-Bridged Monocyclopentadienyl Titanium Compounds. Molecular Structure of {Ti[μ-(η5-C5Me4SiMe2-O)]Me}2(μ-CH2)

2004

Thermolysis of {Ti[μ-(η5-C5Me4SiMe2-O)]Me2}2 affords the methylene-bridged titanium compound {Ti[μ-(η5-C5Me4SiMe2-O)]Me}2(μ-CH2), concurrent with the evolution of methane, the first example of a fu...

First Titanium-Catalyzed anti-1,4-Hydrosilylation of Dienes

2005

1,4-Hydrosilylation of dienes catalyzed by late transition metals constitutes a straightforward access to allylsilanes. However, when unsymmetric dienes are used, it generally leads to a mixture of regioisomers (tail or head products) via Z-specific 1,4-addition. Here we describe the first catalytic anti-1,4-hydrosilylation of dienes using the cheap and stable Cp2TiF2 complex as catalyst. It affords E-allylsilanes in good to excellent yields with an unprecedented regio- and diastereoselectivity. Dehydrogenative double silylation of dienes can be selectively obtained by simply changing the activation protocol of the precatalyst.

Edited by Ilan Marek: Titanium and zirconium in organic synthesis. Wiley-VCH, Weinheim, 2002. xxv?+?512 pp. Price �95.00. ISBN 3-527-30428-2

2002

Homo- and Heterometallic Aluminum and Titanium Complexes of Tridentate (OSO) Ligand:  Synthesis, Structure, and Catalytic Activity

2005

The tridentate (OSO-functions) biphenol, 2,2‘-thiobis{4-(1,1,3,3-tetramethylbutyl)phenol} (tbopH2), reacts with AlMe3 to give [Al2(μ-tbop-κ3O,S,O)2Me2] (1). Alcoholysis of 1 results in the formation of [Al2(μ-OEt)2(tbop-κ3O,S,O)2] (2). The reaction of 2 with TiCl4 gives the trimeric complex [Ti3(μ-OEt)2(μ-tbop-κ3O,S,O)2Cl6] (3)·C6H14. Alkylation of 3·C6H14 with LiMe produces two dimeric complexes, [Ti2(μ-tbop-κ3O,S,O)2Me4] (4) and [Ti2(μ-OE)2(tbop-κ3O,S,O)2Me2] (5)·Et2O. Treatment of [Ti2(μ-OEt)2(tbop-κ3O,S,O)2(OEt)2] with AlMe3 and EtOH afforded the heterobimetallic species, [Ti2Al2(μ-OEt)6(μ-tbop-κ3O,S,O)2(OEt)4] (6). The structures of 1−6 were confirmed by NMR spectroscopy; complexes 1, …

Photocatalytic Activity of TiO2 Coatings Obtained at Room Temperature on a Polymethyl Methacrylate Substrate

2022

Titanium dioxide (TiO2) coatings have a wide range of applications. Anatase exhibits hydrophilic, antimicrobial, and photocatalytic properties for the degradation of organic pollutants or water splitting. The main challenge is to obtain durable anatase nanoparticle coatings on plastic substrates by using straightforward approaches. In the present study, we revealed the preparation of a transparent TiO2 coating on polymethylmethacrylate (PMMA), widely used for organic optical fibres as well as other polymer substrates such as polypropylene (PP), polystyrene (PS), and polycarbonate (PC). The films were spin-coated at room temperature without annealing; therefore, our approach can be used for …

Mixed Titanium–Hafnium Chloridometallate Complexes

2007

The addition of either NEt 3 BzCl or [Ph 3 PNPPh 3 ]Cl (1 equiv. chloride per metal) to a 1:1 mixture of HfCl 4 and TiCl 3 in SOCl 2 results in Ti oxidation and leads to the corresponding salts of the [TiHfCl 10 ] 2- ion. A solution IR investigation in the v(M-Cl) region indicates that this ion is in equilibrium with the homodimetallic [Ti 2 Cl 10 ] 2- and [Hf 2 Cl 10 ] 2- ions. An X-ray study of the NEt 3 Bz + salt reveals an edge-sharing bioctahedral dianion sitting on a crystallographic inversion centre. The crystal is a solid solution of different species with compositional disorder at the metal site, each metal position having the occupancy Ti 0.685 Hf 0.315 . The M-M and M-Cl distance…

Influence of Adsorbed Water on the Activation Energy of Model Photocatalytic Reactions

2017

Two commercial (Merck and Sigma-Aldrich) and two home prepared (HP05 and HP05C) powdered TiO2 photocatalysts were investigated by fast field cycling nuclear magnetic resonance experiments in order to explore the nature of the interactions between water and the solid surfaces. The results were related to the activation energies determined at temperatures ranging from 303 to 353 K for the photocatalytic oxidation in water of three model molecules presenting different interactions with the solid surface (catechol, phenol, and metylbenzoate). The photoactivity results at different temperatures were comparable to each other because the runs were carried out while keeping constant the concentrati…