Dioxouranium(VI) and oxouranium(IV) fluorosulphates and double fluorosulphates of uranium(IV)

UO₂(SO₃F)₂, UO(SO₃F)₂, U(SO₃F)₄ and MU(SO₃F)₆, MMg, Zn have been prepared by reacting UO₂(O₂CCH₃)₂, U(O₂CCH₃)₄, U(O₂CCF₃)₄ and MU(O₂CCH₃)₆ with HSO₃F. The analysis of i.r. spectral data of UO₂(SO₃F)₂, UO(SO₃F)₂ and MU(SO₃F)₆ shows the presence of only one type of SO₃F group with reduced symmetry C_s. In U(SO₃F)₄, two SO₃F groups are bidentate, while the other two are monodentate. A sharp band at 925 cm^?1 in UO₂(SO₃F)₂ is diagnostic of UO₂²⁺. The diffuse reflectance spectra of UO(SO₃F)₂, U(SO₃F)₄ and MU(SO₃F)₆ reveal hexacoordination of U(IV), while the magnetic moments of these compounds support the existence of U(IV). UO₂(SO₃F)₂ and UO(SO₃F)₂ decompose thermally in a single step with the evolution of SO₂F₂ and formation of their respective sulphates.     

Preparation and Ion-Exchange Properties of Mixed Zirconium(IV) Phosphate-Phosphonate Sorbents

Composite sorbents based on Zr(IV) phosphate-hydroxyethylidenediphosphonate with different phosphate-phosphonate ratio were prepared. These sorbents were characterized by elemental analysis, X-ray diffraction, and IR spectroscopy, and their ion-exchange sorption capacity for several transition metals and strontium was studied. The sorption capacity of these sorbents increases with increasing pH.     

Preparation of Globular Zirconium(IV) Hydroxide by Sol-Gel Process

The sol-gel process of the preparation of globular zirconium(IV) hydroxide is described, which involves formation of zirconium(IV) hydroxide sol by electrolysis of zirconium(IV) chloride solution in a one-compartment cell to a Cl/Zr atomic ratio of less than 0.6, gelation of sol droplets in aqueous ammonia, treatment of gel spheres to remove electrolytes, and drying.     

Coordination Adaptable Networks: Zirconium(IV) Carboxylates

Vitrimers are 3D “covalent adaptable networks” (CANs) with flow properties thanks to thermally activated associative exchange reactions. This contribution introduces coordination adaptable networks, or CooANs, that are topologically related to metal–organic frameworks with octahedral Zr₆ clusters as secondary building units in a carboxylic acid-functionalized acrylate-methacrylate copolymer matrix. A series of Zr-CooAN-x materials (x=percent of Zr₆ loading relative to maximum capacity) was synthesized with x=5, 10, 15, 20, 25, 50 and 100. The mechanical and rheological investigations demonstrate vitrimer-like properties for x up to 50, the crosslink migration being ensured by carboxylate ligand exchange, with relaxation becoming slower as the Zr₆ content is increased. The flow activation energy of Zr-CooAN-10 is 92.9±3.6 kJ mol⁻¹. Rapid (30 min) hot-press reshaping occurs at temperatures in the 50–100 °C range under a 3-ton pressure and does not significantly alter the material properties.     

Zirconium(IV) complexes ofSchiff bases

Zirconium(IV)Schiff base derivatives have been synthesised by reacting zirconium isopropoxide with monofunctional bidentateSchiff bases in different stoichiometric ratios. The resulting derivatives of the type Zr(O-Isopr)₃(SB) and Zr(O-Isopr)₂(SB)₂, whereSB ^– is the anion of the correspondingSchiff baseSBH, have been isolated in almost quantitative yields. Their molecular weights have been determined ebullioscopically and their ir spectra recorded.

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Zirkonium(IV)-Komplexe von Schiff-Basen

Zusammenfassung Es wurden Zirkonium(IV)-Schiff-Basen-Derivate in verschiedenen stöchiometrischen Zusammensetzungen über die Reaktion von Zirkoniumisopropoxid mit monofunktionellen zweizähnigenSchiff-Basen synthetisiert. Die Komplexe vom Typ Zr(O-Isopr)₃(SB) und Zr(O-Isopr)₂(SB)₂ [SB ^– als Anion derSchiff-BaseSBH] wurden in fast quantitativer Ausbeute erhalten. Es werden Strukturen vorgeschlagen, die auf ebullioskopisch bestimmten Molekulargewichten und den IR-Spektren basieren.

     

Zirconium(IV) Thorium(IV) and Dioxouranium(VI) Complexes of Salicylidene o-Aminobenzothiol

Salicylidene-o-aminobenzothiol and its 5-chloro and 5-bromo derivatives, dibasic tridentate Schiff bases, dervied from the condensation of o-aminothiol and Salicylaldehyde, 5-chloro salicylaldehyde and 5-bromo salicylaldehyde, were used for coordination with Zr(IV), Th(IV) and UO₂(VI) metal inos. The I:I (metal-ligand) stoichiometry of these complexes is shown by elemental analysis and conductometric titrations. Molecular structure of these complexes are proved by Infra-red spectroscopy and thermogravimetric analysis. Magnetic susceptibility measurements of Zr(IV), Th(IV) and UO₂(VI) complexes show their diamagnetic and octahedral geometry. Results show that all the complexes have solvent molecules in coordination with metal ion.     

Extraction and Spectrophotometric Determination of Zirconium(IV)

Abstract

A sensitive and selective method for the extraction and spectrophotometric determination of Zr(IV) with N-p-chlorophenyl-3,4-,5-trimethoxycinnamohydroxamic acid (PTCHA) has been developed. The binary complex of Zr(IV)-PTCHA is extracted from 2–6 M HCl into chloroform, having a maximum absorbance at 385 nm; molar absorptivity 2.1 × 10⁴ 1 mol^?1 cm^?1. A ternary complex with xylenol orange (Zr-PTCHA-XO) have been studied in chloroform-ethanol media, which absorbs at 540 nm; molar absorptivity 4.3 × 10⁴ 1 mol^?1 cm^?1. The present method is applied for the analysis of zirconium in standard samples.     

Preparation and characterization of bis(methylcyclopentadienyl)titanium(IV) dithizonate complexes

Summary Dichlorobis(methylcyclopentadienyl)titanium(IV) reacts with 1,5-diarylthiocarbazones (aryl=phenyl,p-tolyl,o-chlorophenyl orp-chlorophenyl) in 11 and 12 molar ratios in tetrahydrofuran in the presence of triethylamine, to yield [(MeCp)₂Ti(HDz)Cl], [(MeCp)₂Ti(Dz)] and [(MeCp)₂-Ti(HDz)₂] (MeCp=methylcyclopentadienyl; HDz^– and Dz^2– are the mono- and di-anions of a 1,5-diarylthiocarbazone, H₂Dz).S-Methyl-1,5-diphenylthiocarbazone and [(MeCp)₂TiCl₂] react to give [(MeCp)₂Ti(MeDz)Cl] and [(MeCp)₂Ti(MeDz)₂] (MeDz^– represents the mono-anion ofS-methyl-1,5-diphenylthiocarbazone, HMeDz) in an excess of triethylamine. These new derivatives have been characterised on the basis of elemental analyses, magnetic moment, electrical conductance, i.r.,¹H n.m.r. and electronic spectral studies.     

Preparation and characterization of dichlorobis(N-alkyl-substituted salicylideneaminato)manganese(IV) complexes

A series of dichlorobis(N-alkyl-substituted salicylideneaminato)manganese(IV) complexes, Mn(N-R-Xsal)₂Cl₂, was prepared by the reaction of Mn(NRXsal)₂Cl complexes with hydrogen chloride, where R can be n-C₈H₁₇ (Oct), n-C₁₂H₂₅ (Dod), n-C₁₈H₃₇ (Octd), and CH₂C₆H₅ (Bz) and X can be 5-bromo, 5-nitro, and 5,6-benzo groups. These complexes were characterized by the magnetic susceptibilities, IR and electronic spectra, and cyclic voltammograms.     

Preparation and characterization of bis(cyclopentadienyl)zirconium (IV) oximate complexes

Summary Oximate complexes of bis(cyclopentadienyl)zirconium(IV) chloride (Cp₂ZrCl₂ ) having the general formulae Cp₂Zr(Ox), Cp₂Zr(OxH)Cl and Cp₂Zr(OxH)₂ [where OxH₂ = RC₆H₄C(OH)R: NOH, R = H, Me, R= H, Me, Et, n-Pr; PhC: N(OH)CH(OH)Ph and RC : N(OH)N(OH): CR, R = H, Me and Ph] have been synthesized by reacting bis(cyclopentadienyl)zirconium(IV) chloride with the appropriate oxime in tetrahydrofuran in the presence of triethylamine at room temperature. The complexes have been characterized by their elemental analysis, i.r. and electronic spectra, molecular weight determination, electrical conductance and magnetic measurements.Reprints of this paper are not available.     

Zirconium(IV) oxochloride complexes with xanthines and hypoxanthine

ZrO(LH)₂LCl·H₂O (LH ≡ xanthine, hypoxanthine, theophylline, theobromine) complexes are obtained by boiling under reflux 2:1 molar mixtures of ligand and ZrOCl₂·8H₂O in ethanol-triethyl orthoformate. Characterization studies suggest that these complexes are heptacoordinated polymeric, involving linear ZrOZrO chains and five terminal ligands per Zr⁴⁺ ion, i.e. two LH and one L⁻ (binding through a ring nitrogen), one chloro and one aqua ligand. Caffeine (caf) yielded under the same conditions an addition product of the (ZrOCl₂·3H₂O)₃·caf type. In this compound, caffeine is apparently not involved in coordinative bonding to the zirconium, but is retained in the crystal lattice by means of hydrogen bonds formed between aqua ligand hydrogens and the N(9), O(2) and O(6) caffeine sites.     

Preparation and characterization of diphenyllead(IV) and triphenyllead(IV) complexes with N-protected amino-acids and the dipeptides

The diphenyllead(IV) derivatives of N-benzoyl-(glycine, DL -alanine); N-formyl and N-acetyl-L -phenylalanine; N-monochloroacetyl-L -phenylalanine; N-benzoyl-(glycylglycine, DL -alanylglycine), and N-formyl- N-acetyl- and N-monochloroacetyl-(L -phenylalanylglycine) have been prepared in 1:2 molar ratio by reaction of diphenyllead dichloride with the appropriate amino-acid or dipeptide. Corresponding triphenyllead(IV) derivatives have been prepared in 1:1 molar ratio by reaction of triphenyllead chloride with the thallium(I) salts of the amino-acid or the dipeptide. These complexes have been characterized by elemental analysis, IR and ¹H NMR spectral studies. A polymeric hexacoordinated octahedral structure for diphenyllead(IV), and a five-coordinated distorted trigonalbipyramidal chain-type structure for triphenyllead(IV), complexes is confirmed by IR spectra. The carboxylate group acts in a bidentate manner, not as in diorgano and triorganotin(IV) complexes with these acids, where it is monodentate. The available bonding sites such as amide and peptide carbonyl (CO) and amide and peptide nitrogen atoms are not involved in bonding with lead (IV) and thus are available for bonding with the biological systems. The presence of different N-protecting groups does not affect the coordination sites around lead(IV). The triphenyllead(IV) compounds are relatively more stable than the diphenyllead(IV) compounds.     

Preparation and characterization of manganese(IV) in aqueous acetic acid

Mn(IV) acetate was generated in acetic acid solutions and characterized by UV-vis spectroscopy, magnetic susceptibility, and chemical reactivity. All of the data are consistent with a mononuclear manganese(IV) species. Oxidation of several substrates was studied in glacial acetic acid (HOAc) and in 95:5 HOAc-H(2)O. The reaction with excess Mn(OAc)(2) produces Mn(OAc)(3) quantitatively with mixed second-order kinetics, k (25.0 °C) = 110 ± 4 M(-1) s(-1) in glacial acetic acid, and 149 ± 3 M(-1) s(-1) in 95% AcOH, ΔH(?) = 55.0 ± 1.2 kJ mol(-1), ΔS(?) = -18.9 ± 4.1 J mol(-1) K(-1). Sodium bromide is oxidized to bromine with mixed second order kinetics in glacial acetic acid, k = 220 ± 3 M(-1) s(-1) at 25 °C. In 95% HOAc, saturation kinetics were observed.     

Zirconium (IV), Thorium (IV) and Dioxouranium (VI) Complexes of Dibasic Tridentate Schiff Bases

Dibasic tridentate Schiff bases obtained by the condensation of O -aminobenzoic acid with salicyldehyde and its 5-chloro and 5-bromo derivatives were synthesised and used to pracipitate Zr(IV), Th(IV) and UO₂(VI) metals as complexes. The 1:1 (metal-ligand) stoichiometry of these complexes is shown by elemental analysis, gravimetric estimations and conductometric titrations while the structures of the complexes are proved by i.r. spectra and thermogravimetric analysis. The magnetic susceptibility measurements by Gouy method show, these complexes to be monormeic and diamagnetic. The molar conductance values in nitrobenzene indicate the nonelectrolytic behaviour of the complexes. The results show that the complexes of the type Zr(OH)²L.H²O, Th(OH)²L.H²O and UO²L.H²O are formed having solvent molecule in co-ordination with metal ion.     

Zirconium (IV), Thorium (IV) and Dioxouranium (VI) Complexes of Dibasic Tridentate Schiff Bases

Dibasic tridentate Schiff bases obtained by the condensation of O -aminobenzoic acid with salicyldehyde and its 5-chloro and 5-bromo derivatives were synthesised and used to pracipitate Zr(IV), Th(IV) and UO₂(VI) metals as complexes. The 1: 1 (metal-ligand) stoichiometry of these complexes is shown by elemental analysis, gravimetric estimations and conductometric titrations while the structures of the complexes are proved by i.r. spectra and thermogravimetric analysis. The magnetic susceptibility measurements by Gouy method show, these complexes to be monormeic and diamagnetic. The molar conductance values in nitrobenzene indicate the nonelectrolytic behaviour of the complexes. The results show that the complexes of the type Zr(OH)₃L.H₂O₂ Th(OH)₂ L.H₂O and UO₂L.H₂O are formed having solvent molecule in co-ordination with metal ion.     

Terminal Parent Phosphanide and Phosphinidene Complexes of Zirconium(IV)

The reaction of [Zr(Tren^DMBS)(Cl)] [ Zr1 ; Tren^DMBS=N(CH₂CH₂NSiMe₂Bu^t )₃] with NaPH₂ gave the terminal parent phosphanide complex [Zr(Tren^DMBS)(PH₂)] [ Zr2 ; Zr−P=2.690(2) Å]. Treatment of Zr2 with one equivalent of KCH₂C₆H₅ and two equivalents of benzo‐15‐crown‐5 ether (B15C5) afforded an unprecedented example (outside of matrix isolation) of a structurally authenticated transition‐metal terminal parent phosphinidene complex [Zr(Tren^DMBS)(PH)][K(B15C5)₂] [ Zr3 ; Zr=P=2.472(2) Å]. DFT calculations reveal a polarized‐covalent Zr=P double bond, with a Mayer bond order of 1.48, and together with IR spectroscopic data also suggest an agostic‐type Zr⋅⋅⋅HP interaction [∡_ZrPH=66.7°] which is unexpectedly similar to that found in cryogenic, spectroscopically observed phosphinidene species. Surprisingly, computational data suggest that the Zr=P linkage is similarly polarized, and thus as covalent, as essentially isostructural U=P and Th=P analogues.     

Studies on the Hydrolytic Behavior of Zirconium(IV)

The stability constants of zirconium(IV) hydrolysis species have been measured at 15, 25, and 35 °C [in 1.0 mol-dm^–3 (H,Na)ClO₄] using both potentiometry and solvent extraction. In addition, the solubility of [Zr(OH)₄(am)] has been investigated in a 1 mol-dm^–3 (Na,H)(ClO₄,OH) medium at 25 °C over a wide range of –log [H⁺] (0-15). The results indicate the presence of the monomeric species Zr(OH)³⁺, Zr(OH)₂ ²⁺, Zr(OH)₃ ⁺, and Zr(OH)₄ ⁰(aq) as well as the polymeric species Zr₄(OH)₈ ⁸⁺ and Zr₂(OH)₆ ²⁺. The solvent extraction measurements required the use of acetylacetone. As such, the stability constants of zirconium(IV) with acetylacetone were also measured using solvent extraction. All stability constants were found to be linear functions of the reciprocal of temperature (in kelvin) indicating that H ^o and S ^o are both independent of temperature (over the temperature range examined in the study). The results of the solubility experiments have shown four distinctly different solubility regions. In strongly acidic solutions, the solubility is controlled by the formation of polynuclear hydrolysis species in solution whereas in less acidic solution the formation of mononuclear hydrolysis species becomes dominant. The largest portion of the solubility curve is controlled by equilibrium with aqueous Zr(OH)₄ ⁰(aq) where the solubility is independent of the proton concentration. In alkaline solutions, the solubility increases due to formation of the zirconate ion. The middle region was used to determine the solubility constant (log *K _s10) of Zr(OH)₄(s). From the data in the alkaline region, a value of the stability of the zirconate ion has been determined. This is the first time that the possible evidence for the zirconate ion has been identified in aqueous solution that has previously been found only in the solid phase.     

Determination of Zirconium (IV) and Aluminium (III) in Waste Water

 Zirconium (IV) was determined spectrophotometrically by reaction with quercetin as primary ligand and oxalate as secondary ligand. Polyvinylpyrrolidone (PVP) was used as protective colloid to solubilize the formed zirconium quercetin oxalate ternary complex. The molar absorptivity of the 1:3:1 (zirconium–quercetin–oxalate) complex is 7.31 × 10⁴ L·mol⁻¹ cm⁻¹ at 430 nm with a stability constant of 8.2 × 10²⁰ and its detection limit is 0.16 mg/L. Beer’s law is rectilinear up to 1.46 mg/L of zirconium (IV). The sensitivity index is 1.25 ng cm⁻². The reaction of aluminium (III) with quercetin in presence of PVP as a surfactant has been studied spectrophotometrically. The molar absorptivity of the 1:3 (aluminium–quercetin) complex is 8.09 × 10⁴ × L·mol⁻¹·cm⁻¹ at 433 nm, its stability constant is 2.6 × 10¹³ with sensitivity index of 0.33 ng·cm⁻² and its detection limit is 0.08 mg/L. The optimal conditions for the quantitative determination of zirconium and aluminium were studied. The proposed methods are examined by statistical analysis of the experimental data. The methods are free from interference of most cations and anions. The proposed methods have been used to determine zirconium and aluminium in industrial waste water. Received May 30, 2001; accepted November 2, 2001; published online July 15, 2002     

Zirconium(IV) catalysis in perborate oxidation of iodide

Zirconium(IV) catalyzes perborate oxidation of iodide ion. In acidic solution the oxidation is zero order with respect to perborate, first order with respect to Zr(IV), independent of [H⁺] and exhibits Michaelis-Menten dependence on [I⁻]. Mechanistic pathway of the catalysis is discussed and a rate equation is derived.     

Aqueous Chemistry of Zirconium(IV) in Carbonate Media

The interactions between carbonate ions and zirconium oxychloride are studied by potentiometry, dialysis, and ¹³C‐ and ¹⁷O‐NMR spectroscopy in aqueous media. The nature of the soluble carbonatohydroxo complexes depends on the proportions of hydrogencarbonate and carbonate ions in solution before the addition of zirconium oxychloride. Carbonate media lead to polynuclear entities containing no more than two complexed carbonate ions per Zr⁴⁺. The presence of hydrogencarbonate favors the formation of less condensed and more carbonated complexes such as [Zr(CO₃)₄]⁴⁻. The polycondensation degree of the species decreases when the number of carbonates linked per Zr⁴⁺ increases. In all complexes, the carbonate is bidentate, and the metal atoms are linked via hydroxo bridges. The complexation of carbonate with Zr⁴⁺ occurs for a total carbonate concentration higher than 0.1M . Consequently, in natural medium, the speciation of this metal is governed only by the formation of hydroxo complexes.