Acetylacetone titanium complexes

Titanium, tetrakis(trimethysilyl)oxy-, 3, 334 Titanium, tetranitrato-stereochemistry, 1,94 Titanium, triaquabis(oxalato)-structure, I, 78 Titanium, tris(acetylacetone)-structurc, 1,65 Titanium alkoxides oligomeric structure, 2,346 synthesis ammonia, 2, 338 Titanium chloride photographic developer, 6,99 Titanium complexes acetylacetone dinuclear, 2, 372 alkyl... 

The intense reddish-brown color of the acetylacetone titanium complexes impart a yellow discoloration to white inks. This discoloration is accentuated when the inks are used to print substrates that contain phenol-based antioxidants. The phenoHc compounds react with the organic titanate to form a highly colored titanium phenolate. Replacement of 0.25 to 0.75 moles of acetylacetone with a malonic acid dialkyl ester, such as diethyl malonate, gives a titanium complex that maintains the performance advantages of the acetyl acetone titanium complexes, but which is only slightly yellow in color (505). These complexes still form highly colored titanium phenolates. 

Titanium cesium alum, 6 50 Titanium (II) chloride from disproportionation of titanium (III) chloride, 6 56, 61 Titanium(III) chloride, 6 52, 57 Titanium (IV) chloride, reduction of, with hydrogen, 6 52, 57 Titanium complex compounds, cations, with acetylacetone, [Ti-(C.H. hTiCl, and [Ti(C6H7-0,),]FeCl , 2 119, 120 Titanium(IV) oxide, extraction of, from ilmenite, 5 79, 81 to titanium powder with calcium, 6 47... 

Thus, it is clear why water cannot be used as a solvent Most titanium esters or halides are too reactive and would react with the water solvent rather than the silica surface. One procedure that permits titanation from an aqueous solution is to use a water-soluble titanium complex that resists hydrolysis until after silica dehydration temperatures are reached, when only silanol groups remain. Titanate complexes of triethanolamine [569], acetylacetonate [570], lactate [569], or even peroxide [571] can be used in this way to perform aqueous titanation. 

Titanium, tris(acetylacetone)-structure, 65 Titanium(III) complexes magnetic behavior, 271 spectra, 250 Titanium tetrachloride photoreactivity, 406 Titrimetry, 552 T oluene-3,4-dithiol in gravimetry, 534 metal complexes liquid-liquid extraction, 547 Topochemical reactions, 463 Topotactic reactions, 463 Trans effect, 16, 26,315 six-coordinate compounds, 49 Trans influence square planar complexes, 38 Transition metal complexes d... 

A second type of oxygen-chelated complex that can be formed with acetylacetone is the simple Lewis acid-base adduct. In these complexes acetylacetone does not lose its acidic proton to form an enolate anion, but rather as the neutral molecule in the keto tautomer donates electrons from the oxygens of each carbonyl to an acceptor or acidic species. Examples of this type of complex are the six-coordinate adducts formed between typically strong Lewis adds as tin tetrachloride or titanium... 

In addition to acetylacetone other additives and well-known complexing molecules, like those depicted in Figure 6, were tested in the synthesis of PBT. The new potential catalytic systems were obtained as a reaction mixture of the additives with Ti(0- Bu)4in 1,4-butanediol. This mixtures were used in PBT synthesis without any modification or purification. [31,32] In particular, among the tested additives, it is worthy to note that commercially available titanium complexes are reported for ethylacetoacetate [34] EDTA is one of the most universally employed chelating agent. A different approach was considered in the choice of TEPF and TEPA. TEPA as a phosphonate based compound, can be used as stabilizer for transesteriftcation catalysts in PET synthesis.[35-37] In this case the aim was to verify if this type of compounds have the same effect on the stability of PBT as widely described for PET. 

Other titanium complexes supported by acetylacetonate 17-19, " showing similar structural analogies with 12-16, were reported to have comparable moderate catalytic activities, stereoselectivity and polydispersity for the bulk ROP of rac-LA (Scheme 6.2). In totality, the activity of these complexes seems to be limited, probably by a substantial 7t-donation interaction from the anionic 0,0-bidentate-type ligands to the Ti " Lewis acid that consequently decreases the rate of polymerisation in addition to the sterically crowded complexes limiting the incoming monomer approach. 

Apart from Ti(IV), titanium complexes of other oxidation states (Ti(III) and Ti(II)), such as Ti(acac)3 (acac = acetylacetonate) and TiPh2, also show syndioselective polymerization activity and produce syndiotactic polystyrene. As for the Ti(0) complex, Ti(bipy)3 (bipy = 2,2 -bipyridine), only atactic polymer is produced (Table 14.1, entries 10-12). ... 

Titanium complexes with acetylacetonate (acac) ligands were first tested for the polymerization of styrene by Ishihara et al." and Zambelli et al When activated with MAO, Ti(acac)2Cl2 and Ti(acac)3 can produce syndiotactic polystyrene with low activities, whereas their zirconium analogues only afford atactic polystyrene. Hu and coworkers studied a series of MAO activated 1,3-diketonato titanium complexes (Figure 14.11, 53-57) and found that their activities increased in the following... 

The chelated organic titanates also function as adhesion promoters of the ink binder to printed substrates such as plastic films, paper, and aluminum foil (504). The acetylacetone complexes of titanium are the preferred products for promoting adhesion of printing inks to polypropylene films. 

Mn(II) > Mg(II).270 It should be underlined that titanium and zirconium alkoxides are efficient catalysts for both stages of reaction. Lanthanide compounds such as 2,2/-bipyridyl, acetylacetonate, and o-formyl phenolate complexes of Eu(III), La(III), Sm(III), Er(III), and Tb(III) appear to be even more efficient than titanium alkoxides, Ca or Mn acetates, Sb203, and their mixtures.273 Moreover, PET produced with lanthanides has been reported to exhibit better thermal and hydrolytic stability as compared to PET synthesized with the conventional Ca acetate -Sb203 catalytic system.273... 

Some porous ceramic structures of oxides on titanium (CT2O3, RuOj, MnOj, VOJ obtained by baking films of metal complexes like acetylacetonates on titanium surfaces can also be regarded as chemically modified electrodes Applications... 

Some cyclopentadienyltitanium complexes react with FeClj or iron acetylacetonate with transfer of the cyclopentadienyl ligand from titanium to iron. The yield of ferrocene also depends on the other ligands on titanium. The yield increases with decreasing number of electron-attractive halogen atoms in the molecule (see Table IV). 

Probably substitution of the cyclopentadienyl ligand on alcoholysis and hydrolysis, and its transfer in reactions of di- and monocyclopentadienyl-titanium derivatives with FeClj or iron(II) acetylacetonate, follows a mechanism common for 77-ligand exchange in other metal 77-complexes (see later). 

Apart from the compounds already mentioned, vanadium, manganese, and cobalt chlorides, tetra-alkoxy derivatives of titanium, acetylacetonates of V, Cr, Mo, Mn, and Ni, Cp derivatives of Zr and Nb, and triphenyl phosphine complexes of Ti and Fe were found to be active. Later lanthanide complexes were included in the list of dinitrogen-reducing systems, the most effective being compounds of samarium and yttrium. 

Mixed-ligand precursors are also frequently employed in CSD processing. For example, titanium tetraisopropoxide, which is too reactive to be directly employed in most CSD routes, may be converted into a more suitable precursor by a reaction with either acetic acid or acetylacetone (Hacac). Such reactions are critical in dictating precursor characteristics and have been studied extensively. - Using these reactions, crystalline compounds of known stoichiometry and structure have been synthesized that may subsequently be used as known precursors for film fabrication.Mixed-hgand molecules (carboxylate-alkoxide and diketonate-alkoxide ) represent complexes that are not easily hydrolyzed. A typical structure for one of these compounds is shown in Figure 27.3e. 

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