Adsorption properties of titanium(IV) hexacyanoferrate(II)

The possible use of titanium(IV) hexacyanoferrate(II) as a cation exchanger increased the interest in the preparation of materials with favourable ion exchange capacities and mechanical strength to be used in the columns. A new method of preparation has been developed, which is based on the treatment of spherical particles of titanium hydroxide gel with acidic solutions of potassium hexacyanoferrate(II). Materials of variable composition were obtained. The maximum value for the retention capacity for cesium was found to be of 2.6 meq. Cs per gram of ion exchanger.     

Acceptor properties of titanium 2-naphthyloxides

The behaviour of 2-naphthyloxy titanium compounds towards several aromatic tertiary bases has been studied and a number of complexes TiCl_x(OC₁₀H₇)_4-x, L_y(x = 0 ? 4; L = tertiary base) have been isolated and their properties studied by spectroscopic and thermogravimetric techniques.     

Some ion exchange properties of amorphous titanium (IV) phosphate

An amorphous titanium (IV) phosphate exchanger has been synthesised and characterized through elemental analysis, infrared, and thermogravimetric techniques. Divalent cations Mn, Co, Ni, Cu, Zn, Cd, Hg and Pb in bidistilled water have been exchanged with the proton of the exchanger matrix using a batch method. From these results the thermodynamic selectivity constants and distribution coefficients were calculated, whose values indicate a high selectivity for Pb and Hg. Both cations were successfully separated from a mixture containing all cations studied through column separation experiments.     

Mixed ligand titanium(IV) complexes. Chlorobis(dithiocarbamato)bis(methylsalicylato)titanium(IV) andbis(dithiocarbamato)bis(methylsalicylato)titanium(IV)

Summary Dichlorobis(methylsalicylato)titanium(IV) reacts with potassium or amine salts of dialkyl or diaryl dithiocarbamates in 11 and 12 molar ratios in anhydrous benzene (room temperature) or in boiling CH₂Cl₂ to yield mixed ligand complexes: (AcOC₆H₄O)₂ Ti(S₂CNR₂)Cl (1) and (AcOC₆H₄O)₂ Ti(S₂CNR₂)₂ (2), R=Et, n-Pr, n-Bu, cyclo-C₄H₈ and cyclo-C₅H₁₀. These compounds are moisture sensitive and highly soluble in polar solvents. Molecular weight measurement in conjunction with i.r.,¹H and¹³C n.m.r. spectral studies suggest coordination number 7 and 8 around titanium(IV) in (1) and (2) respectively.     

Aryl-bis(triorganylphosphine)nickel phenoxides

Compounds of general formulatrans-ArNi(PR₃)₂OAr' (R = Et, cyclohexyl; Ar = 2-MeC₆H₄, 2-FC₆H₄; Ar' = 4-FC₆H₄, 4-NO₂C₆H₄) were synthesized by the reaction of Ar'OK with cationic nickel complexes generated by treatment of ArNi(PR₃)₂Cl with TlBF₄. Syntheses of 4-fluorophenoxide complexes, ArNi(PR₃)₂OC₆H₄F-4, additionally give some quantities oftrans-[ArNi(PR₃)₂OC₆H₄F-4][HOC₆H₄F-4] adducts. Exchange reactions MeC₆H₄Ni(PEt₃)₂OC₆H₄F-4 + XC₆H₄OH 2-MeC₆H₄Ni(PEt₃)₂OC₆H₄X + 4-FC₆H₄OH were studied in THF. The equilibrium is shifted to the right as the acidity of ArOH increases. A linear relationship between lgK _eq and pK _a of XC₆H₄OH in DMSO was found. A conclusion concerning the strong polarization of the Ni-O bond was made on the basis of an analysis of the chemical shifts of fluorine atoms in 2-MeC₆H₄Ni(PEt₃)₂OC₆H₄F-4.Translated fromIvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2266–2271, November, 1995.     

Synthesis and some properties of furylacrylates of aluminium(III) and titanium(IV)

Summary Compounds of the type [M(OPrⁱ)_m–n(FA)_n] (where m = 3 and n = 1 to 3 when M = Al; and m = 4 and n = 1 to 4 when M = Ti) have been synthesised by the reactions of aluminium and titanium isopropoxides with furylacrylic acid (HFA) in benzene. The corresponding tertiary butoxide derivatives, [M(OBu^t)_m–n(FA)_n], were also obtained by the alcohol-interchange technique. These compounds have been characterised by elemental analysis, and i.r. and p.m.r. spectra.     

Schiff base derivatives of titanium(IV) and zirconium(IV)

The reactions of a few bifunctional and tridentate Schiff bases with titanium-(IV) and zirconium(IV) isopropoxides in equimolar and bimolar ratios are described. The resulting compounds have been obtained in almost quantitative yields and are of the general formulae M(SB)_x(OPrⁱ)_4?2X (where M = Ti or Zr; SB- = anion of the Schiff base SBH₂ and x = 1 or 2). Their molecular weights have been determined ebullioscopically and IR spectra recorded.     

Reductions by titanium(II) as catalyzed by titanium(IV)

The cobalt(III) complexes, [(NH3)5CoBr]2+ and [(NH3)5CoI]2+ are reduced by Ti(II) solutions containing Ti(IV), generating nearly linear (zero-order) profiles that become curved only during the last few percent of reaction. Other Co(III)-Ti(II) systems exhibit the usual exponential traces with rates proportional to [Co(III)]. Observed kinetics of the biphasic catalyzed Ti(II)-Co(III)Br and Ti(II)-Co(III)I reactions support the reaction sequence: [Ti(II)(H20)n]2+ + [Ti(IV)F5]- (k1)<==>(k -1) [Ti(II)(H2O)(n-1)]2+ + [(H2O)Ti(IV)F5]-, [Ti(II)(H2O)(n-1)]2+ + Co(III) (k2)--> Ti(III) + Co(II) with rates determined mainly by the slow Ti(IV)-Ti(II) ligand exchange (k1 = 9 x 10(-3) M(-1) s(-1) at 22 degrees C). Computer simulations of the catalyzed Ti(II)-Co(III) reaction in perchlorate-triflate media yield relative rates for reduction by the proposed active [Ti(II)(H2O)(n-1)]2+ intermediate; k(Br)/k(I) = 8.     

Monocyclopentadienyl titanium(IV) dithiocarbamate complexes

Preparation of titanium(IV) complexes of the type CpTi(dtc)Cl₂, CpTi(dtc)₂Cl and CpTi(dtc)₃ has been carried out by reacting CpTiCl₃ and respective sodium dithiocarbamate viz. N-(ethyl, m-tolyl), N-cyclopentyl and N-cycloheptyl dithiocarbamates in the desired metal to ligand ratio in refluxing dichlomethane. Studies of the physical properties reveal monomeric and nonelectrolytic nature of these complexes, where dithiocarbamate behaves as bidentate ligand. Therefore, 5, 6 and 7 coordinate structure can be assigned to CpTi(dtc)Cl₂, CpTi(dtc)₂Cl and CpTi(dtc)₃, respectively.     

Phospha(III)guanidinate complexes of titanium(IV) and zirconium(IV) amides

Two procedures for the synthesis of group 4 phosphaguanidine compounds M(R₂PC{NR′}₂)(NR″₂)₃ (M = Ti, Zr; R = Ph, Cy; R′ = ⁱPr, Cy; R″ = Me, Et) are described. Spectroscopic characterization indicated symmetrical bonding of the phosphaguanidinate ligand in solution for the P-diphenyl derivatives whereas the P-dicyclohexyl analogs adopt a more rigid geometry with inequivalent N_amidine substituents within the phosphaguanidinate ligand. X-ray diffraction studies show exclusively monomeric tbp metal centers for a series of derivatives, with a chelating phosphaguanidinate ligand that spans an axial and an equatorial position. Two different conformers have been identified in the solid-state that differ in the relative orientation of the phosphorus R₂P–C substituents with respect to the equatorial plane of the tbp metal. The synthetic protocol was extended to the bimetallic complex, [PhP(C{NⁱPr}₂Ti{NMe₂}₃)CH₂–]₂, which was characterized by crystallography as the meso-form.     

Ammonolysis of mono(pentamethylcyclopentadienyl) titanium(IV) derivatives

Ammonolyses of mono(pentamethylcyclopentadienyl) titanium(IV) derivatives [Ti(eta5-C5Me5)X3] (X = NMe2, Me, Cl) have been carried out in solution to give polynuclear nitrido complexes. Reaction of the tris(dimethylamido) derivative [Ti(eta5-C5Me5)(NMe2)3] with excess of ammonia at 80-100 degrees C gives the cubane complex [[Ti(eta5-C5Me5)]4(mu3-N)4] (1). Treatment of the trimethyl derivative [Ti(eta5-C5Me5)Me3] with NH3 at room temperature leads to the trinuclear imido-nitrido complex [[Ti(eta/5-CsMes)(mu-NH)]3(mu3-N)] (2) via the intermediate [[Ti(eta5-C5Me5)Me]2(mu-NH)2] (3). The analogous reaction of [Ti(eta5-C5Me5)Me3] with 2,4,6-trimethylaniline (ArNH2) gives the dinuclear imido complex [[Ti(eta5-C5Me5)Me])2(mu-NAr)2] (4) which reacts with ammonia to afford [[Ti(eta5-C5Me5)(NH2)]2(mu-NAr)2] (5). Complex 2 has been used, by treatments with the tris(dimethylamido) derivatives [Ti(eta5-C5H5-nRn)(NMe2)3], as precursor of the cubane nitrido systems [[Ti4(eta5-C5Me5)3(eta5-C5H5-nRn)](mu3-N)4] [R = Me n = 5 (1), R = H n = 0 (6), R = SiMe3 n = 1 (7), R = Me n = 1 (8)] via dimethylamine elimination. Reaction of [Ti(eta5-C5Me5)Cl3] or [Ti(eta5-C5Me5)(NMe2)Cl2] with excess of ammonia at room temperature gives the dinuclear complex [[Ti2(eta5-C5Me5)2Cl3(NH3)](mu-N)] (9) where an intramolecular hydrogen bonding and a nonlineal nitrido ligand bridge the "Ti(eta5-C5Me5)Cl(NH3)" and "Ti(eta5-C5Me5)Cl2" moieties. The molecular structures of [[Ti(eta5-C5Me5)Me]2 (mu-NAr)2] (4) and [[Ti2(eta5-C5Me5)2Cl3(NH3)](mu-N)] (9) have been determined by X-ray crystallographic studies. Density functional theory calculations also have been conducted on complex 9 to confirm the existence of an intramolecular N-H...Cl hydrogen bond and to evaluate different aspects of its molecular disposition.     

Monocyclopentadienyl titanium(IV) alkyl xanthate complexes

Titanium(IV) alkyl xanthates of the types CpTi(S₂COR)Cl₂, CpTi(S₂COR)₂Cl and CpTi(S₂COR)₃, where R = CH₃, C₂H₅, C₃H₇, C₄H₉ and C₅H₁₁, have been prepared by the reaction of monocyclopentadienyl titanium(IV) trichloride with potassium alkyl xanthates in anhydrous dichloromethane. Conductance and infrared studies suggest that these complexes are non-electrolytes in which all of the xanthate ligands are bidentate. Proton nmr spectra of these complexes indicate that there is rapid rotation of the cyclopentadienyl ring about the metal-ring axis and for the CpTi(S₂COR)₃ complexes non-equivalence of the alkylxanthate ligands was observed.     

Isolation of dithiocarbazate salts as oxinato-complexes of titanium(IV), zirconium(IV) and hafnium(IV)

Summary Ionic chelate complexes of the type, [(⁵-R)₂ML][dtz] [R=cyclopentadienyl (Cp) or indenyl (C₉H₇); M=Ti^IV, Zr^IV or Hf^IV; HL=oxine; dtz=phenyldithiocarbazate (PhNHNHCS₂)] have been synthesised and characterised. Conductance measurements indicate that the complexes are 11 electrolytes. From i.r. and u.v. spectral studies we conclude that the oxinato-group is chelating. Consequently there is tetrahedral coordination around the metal ion.¹H and¹³C N.m.r. studies are consistent with the stoichiometries. X-ray powder diffraction studies have been made for [(⁵-Cp)₂ZrL][dtz]. For [(⁵-Cp)₂TiL][dtz] and [(⁵-Cp)₂ZrL][dtz] thermal (t.g. and d.t.a.) and mass spectral studies have been carried out.     

Bis(indenyl)titanium(IV) and zirconium(IV) complexes of monofunctional bidentate salicylidimines

Dichlorobis(indenyl)-titanium(IV) and -zirconium(IV), (C₉H₇)₂TiCl₂ and (C₉H₇)₂ZrCl₂, react with bidentate Schiff bases such as salicylidene aniline, salicylidene-o-toluidine, salicylidene-m-toluidine and salicylidene-p-toluidine in a 1:1 molar ratio in refluxing tetrahydrofuran in the presence of triethylamine to yield complexes of the type (C₉H₇)₂Ti(SB)Cl and (C₉H₇)₂Zr(SB)Cl, respectively where SB is the anion of the corresponding Schiff base, SBH. The new derivatives have been characterised on the basis of their elemental analyses, conductance measurements and spectral (IR, ¹H NMR and electronic) studies.     

Racemic titanium(IV) complexes of salicylideneamino acids

New racemic complexes of titanium with Schiff bases derived from condensation of salicylaldehyde with dl-alanine (H₂Sal-dl-Ala) and dl-valine (H₂Sal-dl-Val) have been prepared. The crystal structure of [(Sal-dl-Val)₂Ti·CH₂Cl₂ bis(N-salicylidenevalinato)titanate(IV) CH₂Cl₂] has been solved by single-crystal X-ray diffraction methods; the crystal is a racemate consisting of a pair of enantiomers (Sal-d-Val)₂Ti and (Sal-l-Val)₂Ti. The Schiff-base ligand acts as a double negatively-charged tridentate ONO chelate, coordinated to the titanium atom. The geometry around titanium is a distorted octahedron. The i.r. and u.v.–vis. spectra of the complexes have been evaluated.     

Hydrothermal behavior of titanium(IV) sulfate solutions

The effect of temperature (50 and 75°C) on the viscosity and stability of titanium(IV) sulfate solutions is demonstrated. The changes in the speciation of Ti(IV) in these solutions under the same conditions are reported. The structural transformations of the titanium(IV) sulfate complexes include their conversion into hydroxo(oxo) complexes, the association of the latter, and the growth of the association species up to the size of colloidal particles. This behavior is practically independent of the composition of the initial solution. There can be only variations in the rates of the above hydrolysis stages and, accordingly, in the particle size of the resulting solid phase. By regulating the thermal treatment conditions for titanium(IV) solutions, it is possible to synthesize precursors consisting of nanosized particles (5–30 nm) and having a developed surface morphology. This provides means to obtain titanium dioxide with preset properties.     

Ultrathin functional films of titanium(IV) oxide

Chemistry and physics of thin semiconducting layers of various types are subjects of intense research. Especially when nanotechnology methods such as self-assembly are involved, amazing structural and/or functional properties may appear. Also modern physical methods using variously organized plasma arrangements are able to produce uniform structures with distinctive functionality. In this review, based virtually on our own work, discussions on the preparation, structure, morphology, and function of titanium(IV) oxide nanoscopic thin films are presented. It was shown that structurally and functionally similar titanium(IV) oxide films can be prepared via completely different preparation techniques. Function tests were arranged as “primary”, covering the assessment of the light induced charge separation efficiency, and “secondary”, based on photocatalytic surface oxidations.