Constitution and Thermodynamic Properties of Phosphates of Group IV Elements (Si,Ge, Ti,Zr, Hf)

Abstract

The regularities of phase formation in the systems MO₂ -P₂O₅ (M = Si, Ge, Ti, Zr, Hf) are established and the phase diagrams for them are constructed. In the systems Mo₂ -P 0, (M = Si, Ge) the following compounds are obtained: M₅0(PO₄)₆ and Mp₂O₇ (for Si-cubic, tetragonal and two monoclinic modifications; for Ge-cubic and monoclinic modifications). At low temperatures (up to 500° C) the hexagonal forms SiP₂0₇-0,8 H₂0 and GeP₂0₇·1,6 H₂0 are stable. Two phases are determined in the TiO₂-PO system: the phase of tne variable composition based on 5TiO₂ ^·3P₂0₅ with 40,2 to 54,2 mass % P₂O₅ and another phase TiP₂0₇ (cubic and water-stabilized pseudohexagonal TiP₂0₇ * 3H₂0). Four Compounds are found in the systems MO₂-P₂0₅ (M = Zr, Hf): (MO)₂P₂0 (β- and α-forms for Zr and β-form for Hf), M₃(PO₄)₄, MP₂0₇ and M(PO3)₄. The crystal-chemical analogy is considered between silicium and germanium phosphates, and accordingly between those of zirconium and hafnium. The isolation of titanium phosphates is discussed. The crystallographic, refractometric and thermal characteristics of the compounds and their forms are given as well as the values of electrical and thermal conductivities for cubic modifications of Mp₂O₇. High-temperature mass spectrometry was used to determined the vapour composition and partial pressures as well as the activities of the components and Gibbs free energy in the system GeO₂-P₂O₅ at 1000–1200°C. negative deviations from the ideal are obtained and compared with the results of investigation of the phase diagram for the Geo₂-P₂0₅ system.     

Synthesis and Characterization of Phosphate-Catecholate Chelated Nd(III), Zr(IV), and Al(III) Complexes

Metal phosphates are important catalysts and materials in synthesis chemistry. Herein, we describe the synthesis and characterization of phosphate-catecholate chelated Nd(III), Zr(IV) and Al(III) chlorides ( 2 – 5 ). These species are achieved via ethyl chloride elimination reaction of oxophosphoranes with corresponding metal chlorides. The product 2 – 5 represent a new serial of monometallic and bimetallic phosphate-catecholate chelated metal complexes stabilized by both P−O and catecholate-O donors. These findings pave the way for future explorations of such species in catalysis.     

Synthesis and characterization of Ru(III), Rh(III), Pt(IV) and Ir(III) thiosemicarbazone complexes

Ru(III), Rh(III), Pt(IV) and Ir(III) complexes of 2-furfural thiosemicarbazone as ligand have been synthesised. These complexes have the composition [M(ligand)₂X₂]X (M = Ru(III) Rh(III) and Ir(III) X = Cl and Br) and [Pt(ligand)₂ X₂] X₂ (X = Cl, Br and 1/2SO₄). The deprotonated ligand forms the complexes of the formulae M(ligand-H)₃ and Pt(ligand-H)₃Cl. All these complexes have been characterized by elemental analysis, magnetic measurements, electronic and infrared spectral studies. All the complexes are six-coordinate octahedral.     

Synthesis and characterization of Mn(II), Au(III) and Zr(IV) hippurates complexes

Mn(II), Au(III) and Zr(III) complexes with N-benzoylglycine (hippuric acid) (abbreviation hipH) were synthesized and characterized by elemental analysis, molar conductivity, magnetic measurements, spectral methods (mid-infrared, (1)H NMR, mass, X-ray powder diffraction and UV/vis spectra) and simultaneous thermal analysis (TG and DTG) techniques. The molar conductance measurements proved that all hippuric acid complexes are non-electrolytes. The electronic spectra and magnetic susceptibility measurements were used to infer the structures. The IR spectra of the ligand and its complexes are used to identify the type of bonding. The kinetic thermodynamic parameters such as: E*, DeltaH*, DeltaS* and DeltaG* are estimated from the DTG curves. The free ligand and its complexes have been studied for their possible biological antifungal activity.     

Synthesis and characterization of some Cr(III), Fe(III) and Zr(IV) compounds with substituted o-hydroxy benzophenone

This work presents our data concerning the synthesis and characterization of some Cr(III), Fe(III) and Zr(IV) complexes with substituted (2-hydroxy-4-methoxy-phenyl)-phenyl-methanone - C₁₄H₁₂O₃, denoted by (L1). The synthesis of these complex compounds was performed using melted urea as reaction medium. The obtained complexes have been studied by chemical analysis, IR spectroscopy, X-ray diffraction and thermogravimetric analysis. Based on the data resulting from the thermal behaviour of the studied complex compounds, the kinetic parameters of the thermal decomposition reactions have been determined. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis and characterization of semicarbazone metal complexes of Sn(IV) and Zr(IV)

Three semicarbazonyl ligands were synthesized and used to form six novel organometallic complexes with Ph2SnCl2 and Cp2ZrCl2. All these complexes were characterized by IR,1H NMR,MS and elemental analysis.     

Synthesis and Applications of Poly(Acrylphenylamidrazone-Phenyl-Hydrazide-Acylphenylhydrazine) Chelating Fiber for Preconcentration and Separation of Trae In(III), Zr(IV), Tl(I), V(V), Ga(III) and Ti(IV) from Solution Samples

 An ICP-OES method using a new poly (acrylphenylamidrazone-phenylhydrazide-acylphenylhydrazine) chelating fiber to preconcentrate and separate trace In(III), Zr(IV), Tl(I), V(V), Ga(III) and Ti(IV) ions from solution samples has been established. The new chelating fiber was synthesized using polyacrylonitrile fiber as a starting material and the structure of the chelating fiber was determined by FT infrared spectrometry. The acidity, adsorption rate, re-use, capacity and interference on the adsorption of ions on the chelating fiber as well as the conditions of desorption of these ions from the chelating fiber were investigated by means of inductively coupled plasma optical emission spectrometry (ICP-OES). The results show that the relative standard deviations for the determination of 10 ng/ml In, Tl, Ga and 1 ng/ml Zr, V, Ti were lower than 2.5%. The results obtained for these ions in real solution samples by this method were basically in agreement with the given values with average errors of less than 4%. Received November 29, 2000. Revision May 22, 2001.     

Synthesis, characterization, and reactivity of Ti(IV)-monosubstituted Keggin polyoxometalates

Ti(IV)-monosubstituted Keggin-type polyoxometalates (Ti-POMs), mu-oxo dimer [Bu4N]8[(PTiW11O39)2O] (1), and three monomers [Bu4N]4[PTi(L)W11O39], where L = OH (2), OMe (3), and OAr (4, ArOH = 2,3,6-trimethylphenol (TMP)), have been prepared starting from mu-hydroxo dimer [Bu4N]7[(PTiW11O39)2OH] (5) or heteropolyacid H5PW11TiO40 or both. The compounds have been characterized by elemental analysis, IR, UV-vis, and multinuclear (31P, 1H, 183W) NMR. The interaction of 1 and 3-5 with H2O in MeCN produces 2. The hydrolysis constants, estimated from 31P and 1H NMR data, are 0.006 and 0.04 for 1 and 3, respectively. Studies by 31P NMR, IR, potentiometric titration, and cyclic voltammetry revealed that 1-3 and 5 afford the same protonated titanium peroxo complex [Bu4N]4[HPTi(O2)W11O39] (I) upon interaction with aqueous H2O2 in MeCN. The rates of formation of I correlate with the rates of hydrolysis of the Ti-POMs and follow the order of 5 > 1 > 3. A two-step mechanism of the reaction of Ti-POMs with H2O2, which involves hydrolysis of the Ti-L bonds to yield 2 followed by fast interaction of 2 with hydrogen peroxide producing I, is suggested. The equilibrium constant for the reaction of 2 with H2O2 to yield I and H2O, estimated using 31P NMR, is 10. The interaction of the Ti-POMs with TMP follows the trends similar to their interaction with H2O) and requires preliminary hydrolysis of the Ti-L bonds. All of the Ti-POMs catalyze the oxidation of TMP with H2O2 in MeCN to give 2,3,5-trimethyl-p-benzoquinone and 2,2',3,3',5,5'-hexamethyl-4,4'-biphenol. The product distribution is similar for all of the Ti-POMs. The catalytic activities of the Ti-POMs correlate with the rates of formation of I and follow the order of 2 > 5 > 1 > 3. The findings lay a basis for a better understanding of the nature of the reactivity of titanium in Ti-catalyzed oxidations.     

Synthesis and physicochemical properties of the Al(III), Ga(III) and In(III) complexes with chrysin

New solid compounds of Al(III), Ga(III) and In(III) with chrysin were obtained. Their composition and some physicochemical properties were studied by thermogravimetric analysis, UV-vis, infrared and solid state ¹³C NMR spectroscopies. Upon heating the hydrated compounds M(C₁₅H₉O₄)₃·nH₂O decomposed to the oxides. The structure of the compounds was elucidated on the basis of obtained results.     

Efficiency and application of poly(acryldinitrophenylamidrazone-dinitroacrylphenylhydrazine) chelating fiber for pre-concentrating and separating trace Au(III), Ru(III), In(III), Bi(III), Zr(IV), V(V), Ga(III) and Ti(IV) from solution samples

Poly(acryldinitrophenylamidrazone-dinitroacrylphenylhydrazine) chelating fiber was synthesized from polyacrylonitrile fiber and used for enrichment and separation for traces of Au(III), Ru(III), In(III), Bi(III), Zr(IV), V(V), Ga(III) and Ti(IV) ions from solution samples. The acidity, rate, re-use, capacity and interference on the adsorption of ions on the chelating fiber as well as the conditions of desorption of these ions from the chelating fiber were investigated by means of inductively coupled plasma optical emission spectrometry. The results show that 10-100 ngml(-1) of Au(III), Ru(III), In(III), Bi(III), Zr(IV), V(V), Ga(III) and Ti(IV) ions can be quantitatively enriched by the chelating fiber at a 2 mlmin(-1) of flow rate in the range pH 4-5, and desorbed quantitatively with 20 ml of 5 M HCl for In(III), Bi(III), Zr(IV), V(V), Ga(III), Ti(IV) and 20 ml of 4 M HCl+2% CS(NH(2))(2) solution for Au(III), Ru(III) (with recovery>95%). 50- to 500- fold excesses of Fe(III), Al(III), Mg(II), Mn(II), Ca(II), Cu(II), Ni(II) ions cause little interference in the concentration and determination of analyzed ions. When the fiber was reused for 8 times, the recoveries of the above ions enriched by the fiber were still over 87%. The relative standard deviations (RSDs) for the enrichment and determination of 10 ngml(-1) Au, Ru, In, Bi, Ga and 1 ngml(-1) Zr, V, Ti were lower than 3.0%. The results obtained for these ions in real solution samples by this method were basically in agreement with the given values with average errors of less than 6.3%. FT-IR spectra show that existence of NNCNHNH, OCNHNH and NO(2) functional groups are verified in chelating fiber, and Au(III) or Ru(III) is mainly combined with nitrogen (or oxygen) of the groups to form a chelate complex.     

Synthesis and Study of Acid-Basic Properties of Ti(IV) and Zr(IV) Phosphates Immobylized in the Matrix of Clinoptilolite

Abstract

By combination of the ionexchange and ionic-molecular layering methods [1], the synthesis of natural zeolite derivatives (clinoptilolite) containing in its composition nano-size fragments of Ti(IV) and Zr(IV) phosphates was performed. It was determined by the X-Ray method, that the phosphates of Ti(IV) and Zr(IV) replicate crystal lattice of zeolite, manifesting in enhancing the line's intensity on X-Ray patterns. The Brensted's and Lewis's spectra of acidic centers distributions were obtained by Hammett's indicator spectrophotometric method [2] in the interval of pK, values from -4.4 to 14.2, which have shown that P(V) of the derivatives is represented mainly by HPO₄- and H₂PO₄-groups, with predomination of these latter. It is shown that the force of Brensted's acidic centers, influenced by H₂PO₄-groups. remains at the level of H₂PO_(aq)-anion, and the force of the centers due to HPO₄-groups shifts into alkaline region, about 0,5 unit of pK. The strong acidic Lewis's centers were detected at the levels of pK, from 0 to -4.0. The spectra of Ti(IV) and Zr(IV) phosphates is presented in (1) and (2) respectively. A set of the acquired results makes possible a suggestion about using P(V)-containing derivatives in processes which are catalyzed both with Brensted's and Lewis's centers participation.     

Synthesis and characterization of diethylphosphino Ga(III) and In(III) complexes with covalent metal-phosphorus bonds

The covalent derivatives [Et₂M-PEt₂]₃ (M = Ga, In) have been prepared from Lewis acid-base complexes, R₃M.PHEt₂, by alkane elimination and characterized by elemental analyses, IR, ¹H and ³¹P NMR spectroscopy. Features of the mass spectra reveal a trimeric form and the strength of the [M-P]_n ring. For the compound [ClMeGa-PEt₂]_n, spectral data are consistent with a weakening of the [Ga-P]_n chain, in good agreement with the pyrolysis results.     

Bis(dimethylmetall(III)glyoximato)metallate(II) (metall(III) = Al,Ga, In,metall(II) = Ni,Pd, Pt,Cu)

When the trimethyl derivatives of aluminium, gallium and indium react with glyoximato metallates, (R₂C₂N₂(O)OH)₂Met^II (R = H, CH₃; Met^II = Ni, Pd, Pt, Cu), in a $\text{2}\text{1}$ molar ratio, 2 mol of methane are evolved and monomeric bis(dimethylmetal(III)glyoximato)metallates(II) (metal(III) = Al, Ga, In) are formed in high yields. The vibrational and NMR spectra of the new complexes were measured and were partly resolved. The X-ray structure determinations of two of these compounds show non-planar structures of approximate C_2h and C₂ symmetry, respectively, with weak metal(III)?metal(II) π-interactions.     

Synthesis and characterization of chlorodiorganotin(IV) derivatives of O,O-alkylene dithiophosphates

The O,O-alkylene dithiophosphates of chlorodiorganotin(IV), (where R = Me, G =–CMe₂CMe₂–; R = Me, Bu; G =–CH₂CMe₂CH₂–, and R = Me, Bu, Ph; G =–CHMeCH₂CMe₂–) have been synthesized by reactions of diorganotindichloride with the ammonium salts of O,O-alkylene dithiophosphates in 1 : 1 molar ratio in benzene. These compounds have been characterized by IR, ¹H, ¹³C, ³¹P, and ¹¹⁹Sn NMR spectroscopy. Unlike triorganotin derivatives, the ligand is bidentate in these derivatives.     

Synthesis of Thin-Film Acidic Ti(IV) and Zr(IV) Phosphates Deposited on Surface of Fiber and Investigation their Properties

Abstract

Cellulosic fibres present great interest as matrix for non-organic synthesis with the use of ion-molecular layering method [I]. This method consists in realization of the successive reactions with the surface functional groups. Synthesized materials can he of scientific and technical interest.     

Complexes of tetra-tert-butyl-tetraazaporphine with Al(III) and Zr(IV) cations as fluoride selective ionophores

In this work, complexes of Zr(IV) and Al(III) cations with 2,7,12,17-tetra-tert-butyl-5,10,15,20-tetraazaporphine (TAP) were tested as ionophores in plasticized PVC membranes of ion-selective electrodes. It was found that both tested ionophores show enhanced affinity towards fluoride anion. High fluoride selectivity was observed in the presence of anionic or cationic additives in the membrane, which indicates that proposed compounds work according to charged or neutral carrier mechanism, depending on membrane composition and pretreatment.tert-Butyl substituents, present in the structure of tested compounds, were supposed to prevent formation of ionophore dimers within the membrane phase. This process was found to be responsible for some unfavorable potentiometric properties of electrodes based on complexes of Zr(IV) and Al(III) cations with porphyrins (compounds closely related to tetra-tert-butyl-5,10,15,20-tetraazaporphine). As it was shown using spectrophotometrical measurements, Al(III)-TAP was not susceptible to dimerization, while dimer formation was observed for Zr(IV)-TAP. In full agreement with these observations, electrodes with membranes containing Al(III)-TAP responded in near-Nernstian and fast manner towards fluoride anion, while the employment of Zr(IV)-TAP as ionophore resulted in super-Nernstian and sluggish response. Plasticized PVC membranes doped with Al(III)-TAP and 20 mol% of lipophilic anionic additives shown remarkable F⁻ selectivity, with selectivity coefficients, , as follows: −4.4 (Y⁻Br⁻), −4.3 (Cl⁻), −4.2 (NO₃⁻), −3.6 (SCN⁻), −2.9 (ClO₄⁻).     

A chromogenic calixarene hydroxamic acid for the sequential separation of Ti(IV) and Zr(IV)

A new chromogenic calixarene with hydroxamic acid as chelating agent was synthesized by partial reduction of nitrocalixarene which was subsequently coupled with coumarin chloride. The reagent showed selective and quantitative extraction of Ti(IV) into chloroform at 6 M HCl and that of Zr(IV) at 0.5 M HCl. A facile liquid-liquid extraction method for the separation and spectrophotometric determination of Ti(IV) and Zr(IV) has been proposed. The validity of the method was checked by separating several synthetic mixtures. The method was successfully applied to the analysis of piezoelectric lead-zirconium-titanate (PZT) samples. The method shows remarkable simplicity and selectivity. The method can also be used for the determination of Ti(IV) and Zr(IV) in various environmental samples. The article is published in the original.