Crystal structures of hafnium(IV) and zirconium(IV) complexes with β-diketones

Preparation methods are developed for a number of 7- and 8-coordinated derivatives of Hf(IV) and Zr(IV) with β-diketonate ligands (R¹-CO-CH-CO-R²). The complexes obtained are examined by IR spectroscopy, mass spectrometry, and X-ray crystallography. All structures are molecular. The M-O distances fall within 2.09–2.28 Å. In the crystals, the molecules are joined only by van der Waals interactions. It is demonstrated that the series of hafnium(IV) and zirconium(IV) chelates with identical ligands are isostructural, and the introduction of CF₃- or tert-butyl groups in the terminal positions of the ligand as well as chlorine substitution for one of the ligands do not essentially affect the basic geometric characteristics of the ligand in the complexes.     

Study of temperature dependence of saturated vapour pressure of zirconium(IV) β-diketonates

By means of a tensiometric flow method and a static method with a silica-membrane zero gauge, the dependences of saturated vapour pressure on temperature were obtained for the complexes of zirconium(IV) with acetylacetone, trifluoroacetylacetone, hexafluoroacetylacetone, dipivaloylmethane and pivaloyltrifluoroacetone. The thermodynamic characteristics of the evaporation and sublimation of these complexes were determined.     

Spectroscopic,electrocatalytic, and photoelectrochemical characteristics of mixed-ligand bis(β-dicarbonylato) phthalocyanine complexes of zirconium(IV) and hafnium(IV)

The electronic absorption (EAS) and fluorescence spectra and electrocatalytic and photoelectrochemical characteristics of mixed-ligand complexes of zirconium(IV) and hafnium(IV) based on phthalocyanines in solutions and in thin films were investigated. It was established that a significant bathochromic shift of the Q band and redistribution of the intensities in the absorption bands are observed in the electronic absorption spectra. It was shown that films of the synthesized compounds are promising for use as photosensitizers and electrochemical sensors for oxygen in solution. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 44, No. 3, pp. 133–137, May–June, 2008.     

Volatile zirconium complexes with sterically hindered β-diketonates: Structure and thermal properties

The structure and thermal properties of a novel zirconium(IV) complex with a methoxy substituted β-diketonate ligand tetrakis-(2-methoxy-2,6,6-trimethylheptane-3,5-dionato)zirconium are described. The complex sublimes without decomposition under low pressure (10^–2 Torr) at 200 °C. The crystal structure of the complex is molecular and is composed of two structural Zr(zis)₄ isomers in a 1:1 ratio. The crystallographic data are as follows: C₈₈H₁₅₂F₂₄O₂₄Zr₂, P-1, a = 12.1350(7) Å, b = 19.7733(10) Å, c = 21.0526(12) Å, α = 83.338(2)°, β = 89.571(2)°, γ = 73.515(2)°, V = 4809.5(5) ų, Z = 2, d = 1.227 g/cm³. The coordination environment of the zirconium atom consists of eight oxygen atoms from four β-diketonate ligands; the coordination polyhedron is a square antiprism. The Zr–O distances are in a range 2.127-2.202 Å. The thermal properties of the complex are studied by TG–DTA. The effect of the crystal structure (molecular packing) on the volatility and thermal properties is compared for the new complex and two other analogous zirconium complexes with β-diketonate ligands containing bulky terminal substituents. The results of the mass spectrometric study of thermal behavior of the complexes on programmed heating of vapor under the conditions similar to those in a hot wall CVD reactor under low pressure, including the decomposition in the presence of oxygen, are discussed.     

Crystal structure of volatile pyridine adducts of trimethylplatinum(IV) β-diketonates

The structures of volatile pyridine adducts of trimethylplatinum(IV) β-diketonates derived from acetylacetone (Hacac) and dipivaloylmethane (Hdpm) are studied for the first time. Their preparation is reported and the data of thermal studies obtained by the DTA technique are presented. The structures of the compounds in question comprise monomeric complexes. The platinum atom is coordinated to three carbon atoms of methyl groups, two oxygen atoms of β-diketone, and the nitrogen atom of the pyridine molecule. The (PtC₃O₂N) coordination core has the shape of a slightly distorted octahedron. The geometrical characteristics of the coordination cores are the following: in all complexes, the values of Pt-O, Pt-C_Me, Pt-N bond lengths and O-Pt-O chelate angles fall within 2.122–2.146 Å, 1.986–2.079 Å, 2.131–2.186 Å and 89.3–90.6° respectively.     

Volatile fluorinated trimethylplatinum(IV) β-diketonates with pyridine: Synthesis,properties, and structure

Volatile fluorinated trimethylplatinum(IV) β-diketonates with pyridine (CH₃)₃Pt(CH₃-CO-CH-CO-CF₃)Py (I) and (CH₃)₃Pt(CF₃-CO-CH-CO-CF₃)Py (II) obtained from trifluoroacetylacetone and hexafluoroacetylacetone were studied. The synthesis, elemental analysis data, and IR spectra were described. X-Ray diffraction analysis was performed and the crystal structure was determined; the geometric characteristics of complexes I and II were obtained. Both structures are monomeric molecular structures. The molecules in the crystal are connected only by weak van der Waals forces. The coordination polyhedron of platinum in I and II is a slightly distorted octahedron. The shortest Pt…Pt distances are 6.639 Å (for I) and 6.254 Å (for II). The average P-O, Pt-N, and P-C distances are 2.157, 2.182, and 2.030 Å, respectively. The deviations of the bond angles at Pt atoms from ideal values of 90° do not exceed 4.8°.     

X-ray structural study of fluorinated β-diketonate complexes of zirconium(IV)

Three novel complexes of zirconium(IV) are prepared and characterized by single crystal X-ray diffraction: zirconium(IV) pivaloyltrifluoroacetonate Zr(ptac)₄, zirconium(IV) trifluoroacetylacetonate Zr(tfac)₄, and zirconium(IV) hexafluoroacetylacetonate Zr(hfac)₄. Crystal data for C₃₂H₄₀F₁₂ZrO₈: a = 19.9842(6) Å, b = 11.8417(3) Å, c = 16.4831(5) Å; β = 95.2880(10)°, monoclinic, space group Cc, Z = 4, d _calc = 1.491 g/cm³, R = 0.061. Crystal data for C₂₀H₁₆F₁₂ZrO₈: a = 21.5063(15) Å, b = 7.9511(5) Å, c = 16.0510(10) Å; β = 113.736(4)°, monoclinic, space group C2/c, Z = 4, d _calc = 1.860 g/cm³, R = 0.047. Crystal data for C₂₀H₄F₂₄ZrO₈: a = 15.3533(13) Å, b = 20.2613(15) Å, c = 19.6984(17) Å; β = 95.828(2)°, monoclinic, space group P2₁/c, Z = 2, d _calc = 2.004 g/cm³, R = 0.078. All the structures are molecular and include isolated mononuclear Zr(β-dik)₄ complex molecules. Coordination environment of zirconium atom is made by eight oxygen atoms of four β-diketonates; the coordination polyhedron is an almost regular square antiprism. The Zr-O distances fall within 2.14–2.23 Å. Complexes in the structures are joined by van der Waals interactions. Using the structural data, the van der Waals energies of crystal lattices of the studied compounds are calculated by the atom-atom potential method.     

Synthesis and properties of ms- and β-substituted Pt(II) and Pt(IV) tetraphenylporphyrinates

The interaction of 5,10,15,20-tetraphenylporphyrin, 5,10,15,20-tetra-(4-chlorophenyl)porphyrin, 2-bromo-5,10,15,20-tetraphenylporphyrin, and 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin with platinum(II) chloride in boiling phenol has been studied. The corresponding platinum(II) porphyrinates have been synthesized; their subsequent treatment with bromine in chloroform resulted in platinum(IV) porphyrinates. The Pt(II) and Pt(IV)(Br)₂ porphyrinates have been identified by elemental analysis, electron absorption, IR, and ¹H NMR spectroscopy.     

Mechanochemical synthesis of vanadium(III) β-diketonates

The effect of the mechanical treatment conditions and of the nature of reactants on the course of the solid-phase reaction of vanadium(III) chloride with sodium β-diketonates and potassium tetramethylheptanedionate, on the yield of the reaction products, and on some properties of the activated mixtures was examined. A method was developed for the synthesis of vanadium(III) β-diketonates by the solid-phase mechanochemical reaction of vanadium(III) chloride with appropriate sodium or potassium β-diketonate, followed by sublimation or extraction.     

Some new ion-pair complexes of tin(IV) and dihalotin bis(β-diketonates)

Interaction between tin tetrachloride and p-fluorobenzoylacetone and 2-thenoyltrifluoroacetone in cold benzene afforded, insoluble ion-pair complexes of the type [Cl₂SnL₂]Sn²⁺Cl₆²⁻¹. The same system in refluxing benzene yielded soluble covalent derivatives of the type X₂SnL₂ (where X = Cl, Br, I and L = p-fluorobenzoylacetonate and 2-thenoyltrifluoroacetonate anion). Based on the physical properties and spectral measurements these derivatives were shown to possess octahedral structure.     

Mechanism of electrochemical synthesis of copper(II) β-diketonates

Formation of copper -diketonates in electrolysis of a solution of acetylacetone in acetonitrile in the presence of oxygen, with tetraethylammonium bromide as supporting electrolyte, was studied.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 11, 2004, pp. 1804–1807.Original Russian Text Copyright © 2004 by Kostyuk.     

Optical chemosensor properties of europium(III) tris(β-diketonates)

Interaction between Eu(III) tris(β-diketonates) and ammonia vapors increases the luminescence of Eu(III). A mechanism for the effect of analyte molecules on the intensification of Eu(III) luminescence is proposed. The mechanism includes the displacement of water molecules from the coordination sphere of europium(III).     

Synthesis and characterization of new unsymmetrical β-diketiminate tris(dimethylamido)hafnium(IV) complexes as potential precursors for the MOCVD of HfO2

The synthesis and characterization of four new unsymmetrical β-diketiminate tris(dimethylamido)hafnium(IV) complexes, [2-(2,6-diisopropylphenyl)amino-4-(phenyl)imino-2-pentene]tris(dimethylamido)hafnium(IV) (5a), [2-(2,6-diisopropylphenyl)amino-4-(4-methylphenyl)imino-2-pentene]tris(dimethylamido)hafnium(IV) (5b), [2-(2,6-diisopropyl-phenyl)amino-4-(4-methoxyphenyl)imino-2-pentene]tris(dimethylamido)hafnium(IV) (5c), and [2-(2,6-diisopropylphenyl)amino-4-(4-chlorophenyl)imino-2-pentene]tris(dimethylamido)hafnium(IV) (5d), are described. Amine elimination reactions work well for introducing unsymmetrical β-diketiminates2-(2,6-diisopropylphenyl)amino-4-(phenyl)imino-2-pentene (4a), 2-(2,6-diisopropylphenyl)amino-4-(4-methylphenyl)imino-2-pentene (4b), 2-(2,6-diisopropylphenyl)amino-4-(4-methoxyphenyl)imino-2-pentene (4c), and 2-(2,6-diisopropylphenyl)amino-4-(4-chlorophenyl)imino-2-pentene (4d) to the tetrakis(dimethylamino)hafnium centre. We discuss the synthetic procedures and characterization using ¹H NMR, ¹³C NMR, IR, mass spectroscopy, and elemental analysis. According to the IR and NMR spectra, unsymmetrical β-diketiminate ligands are bidentate, coordinating through two nitrogens to hafnium.     

Phosphato, chromato, and perrhenato complexes of titanium(IV) and zirconium(IV) containing Kläui's tripodal ligand

Treatment of titanyl sulfate in dilute sulfuric acid with 1 equiv of NaL(OEt) (L(OEt)(-) = [(eta(5)-C(5)H(5))Co{P(O)(OEt)(2)](3)](-)) in the presence of Na(3)PO(4) and Na(4)P(2)O(7) led to isolation of [(L(OEt)Ti)(3)(mu-O)(3)(mu(3-)PO(4))] (1) and [(L(OEt)Ti)(2)(mu-O)(mu-P(2)O(7))] (2), respectively. The structure of 1 consists of a Ti(3)O(3) core capped by a mu(3)-phosphato group. In 2, the [P(2)O(7)](4-) ligands binds to the two Ti's in a mu:eta(2),eta(2) fashion. Treatment of titanyl sulfate in dilute sulfuric acid with NaL(OEt) and 1.5 equiv of Na(2)Cr(2)O(7) gave [(L(OEt)Ti)(2)(mu-CrO(4))(3)] (3) that contains two L(OEt)Ti(3+) fragments bridged by three mu-CrO(4)(2-)-O,O' ligands. Complex 3 can act as a 6-electron oxidant and oxidize benzyl alcohol to give ca. 3 equiv of benzaldehyde. Treatment of [L(OEt)Ti(OTf)(3)] (OTf(-) = triflate) with [n-Bu(4)N][ReO(4)] afforded [[L(OEt)Ti(ReO(4))(2)](2)(mu-O)] (4). Treatment of [L(OEt)MF(3)] (M = Ti and Zr) with 3 equiv of [ReO(3)(OSiMe(3))] afforded [L(OEt)Ti(ReO(4))(3)] (5) and [L(OEt)Zr(ReO(4))(3)(H(2)O)] (6), respectively. Treatment of [L(OEt)MF(3)] with 2 equiv of [ReO(3)(OSiMe(3))] afforded [L(OEt)Ti(ReO(4))(2)F] (7) and [[L(OEt)Zr(ReO(4))(2)](2)(mu-F)(2)] (8), respectively, which reacted with Me(3)SiOTf to give [L(OEt)M(ReO(4))(2)(OTf)] (M = Ti (9), Zr (10)). Hydrolysis of [L(OEt)Zr(OTf)(3)] (11) with Na(2)WO(4).xH(2)O and wet CH(2)Cl(2) afforded the hydroxo-bridged complexes [[L(OEt)Zr(H(2)O)](3)(mu-OH)(3)(mu(3)-O)][OTf](4) (12) and [[L(OEt)Zr(H(2)O)(2)](2)(mu-OH)(2)][OTf](4) (13), respectively. The solid-state structures of 1-3, 6, and 11-13 have been established by X-ray crystallography. The L(OEt)Ti(IV) complexes can catalyze oxidation of methyl p-tolyl sulfide with tert-butyl hydroperoxide. The bimetallic Ti/ Re complexes 5 and 9 were found to be more active catalysts for the sulfide oxidation than other Ti(IV) complexes presumably because Re alkylperoxo species are involved as the reactive intermediates.     

Physicochemical studies of metal β-diketonates—IV: Magnetic and spectral properties of divalent transition metal complexes of 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione

The complexes of 4,4,4 - trifluoro - 1 - (2 - thienyl) - 1,3 - butanedione (Htftbd) with some divalent metal ions of the formula [M(tftbd)₂] (M = Mn, Co, Ni, Cu, Zn, Pd) and [M(tftbd)₂(H₂O)₂] (M = Mn, Fe, Co, Ni, Zn) have been prepared and characterised using magnetic susceptibility measurements over the temperature range 300–380°K and reflectance electronic spectra. Though the magnetic and spectral properties of the hydrated and corresponding anhydrous chelates are similar, Mn(tftbd)₂ shows evidence of an antiferromagnetic interaction (θ = 32°) while Ni(tftbd)₂ provides an example of a ferromagnetic interaction (θ = −10°).The sulphur atoms of the thienyl rings do not bond to the metals, consequently, the stereochemistries of these complexes resemble very closely the corresponding acetylacetonates.     

Liquid secondary ion mass spectrometry of several β-diketonates of cobalt(III) and chromium(III)

The positive, liquid secondary ion (LSI) mass spectra of six cobalt(III) and three chromium(III) (β-diketonates ligand = L^?) were examined in a 3-nitrobenzyl alcohol matrix. The complexes of both metals yield clean, matrix-free mass spectra, but there are important differences between them. The cobalt compounds show prominent peaks assignable to the molecular ion, CoL ₃ ⁺ , of the monomeric chelates, together with abundant dimeric ions, such as Co₂L ₄ ⁺ and Co₂L ₃ ⁺ ; in contrast, chromium complexes show protonated monomers, CrL₃H⁺, in addition to ionized monomers, CrL ₃ ⁺ , and only minor formation of dimeric ions. The collisionally-activated dissociation (CAD) mass spectrum of Co₂L ₄ ⁺ shows fragmentation to CoL ₂ ⁺ and Co₂L ₃ ⁺ . That of Co₂L ₃ ⁺ shows fragmentation only to dimeric ions, including Co₂L ₂ ⁺ and, for thienyl or phenyl substituted ligands, to Co₂L₂Ar⁺ or Co₂LAr⁺ (Ar = thienyl or phenyl). Neither Co₂L ₄ ⁺ nor Co₂L ₃ ⁺ dissociates to the CoL ₃ ⁺ ion. The LSI mass spectrum of a mixture of two different cobalt chelates shows dimeric ions containing both types of ligand, which can be explained by ion-molecule reactions in the selvedge region. The differing behaviors of the cobalt and chromium complexes is attributed to the relatively greater stability of the +2 oxidation state for cobalt than for chromium.     

Synthesis,characterisation and ion exchange properties of hybrid organic–inorganic composite material: polyacrylamide zirconium (IV) iodosulphosalicylate

ABSTRACT

Contamination of groundwater by heavy metal is one of the most emerging and serious environmental problems. There are so many methods which are available to overcome these problems. Among various available methods, hybrid organic–inorganic ion exchange resin has become more popular due to certain advantages over other available conventional methods; hence, in the present proposed work, we synthesised a hybrid organic–inorganic composite material polyacrylamide zirconium (IV) iodosulphosalicylate by using the sol-gel technique. Synthesised resin was characterised by various methods like Infrared spectroscopy and Thermogravimetric analysis-Differential thermal analysis. Various samples of this ion exchange resin are prepared by changing the condition of synthesis, i.e. concentration of acrylamide to rationalise the ion exchange capacity of the synthesise hybrid organic–inorganic ion exchange resins. A mixture of 0.1 M potassium iodate, 0.1 M sulphosalicylic acid and 0.1 M acrylamide was added dropwise to 0.4 M zirconium oxychloride accompanied by constant stirring for 8 h using magnetic stirrer at 70°C to yield polyacrylamide zirconium (IV) iodosulphosalicylate with maximum ion exchange capacity. Ion exchange capacity of synthesised resin was determined by column method and the maximum ion exchange capacity was found for Pb(II). Determination of k_d values shows that the resin was highly selective for Pb (II).The selectivity for Pb was also evaluated by using certain binary mixture separation such as Ni (II)-Pb(II), Cu(II)-Pb(II), Cd(II)-Pb(II), Sr(II)-Pb(II), Ba(II)-Pb(II),Zn(II)-Pb(II) and Mg(II)-Pb(II).