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PubMed2004

Preparation of polyacrylamide and gamma-zirconium phosphate nanocomposites by intercalative polymerization.

A new inorganic-organic nanocomposite of polyacrylamide (PAM) and gamma-zirconium phosphate (gamma-ZrP) was prepared by intercalative polymerization. Intercalation of acrylamide (AM) monomer in gamma-ZrP was investigated by sonochemical and refluxing methods. High-intensity ultrasound does not induce the polymerization of AM but enhances greatly the intercalation rate. On the other hand, ultrasound also enhanced hydrolyzation of -CONH2 and shrinkage of PAM gel. The interlayer distance of AM-intercalated gamma-ZrP is 16.4 A. The polymerization and intercalation of AM occurred nearly at the same time by refluxing method. The same gamma-ZrP/PAM nanocomposites were obtained with (NH4)2S2O8 treatment.

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PubMed2003

Molecular simulations of smectites intercalated with a zirconium complex ion.

Molecular mechanics simulations using the Cerius2 modeling environment have been applied to study the structures of dioctahedral smectites intercalated with the zirconium cation [Zr4(OH)12(H2O)12]4+. The substitutions in the silicate layers influence the sublimation energy in these types of intercalated layer structures. Charge distribution in the smectite layer was analyzed in relation to the interlayer structure. Tetrahedral substitutions in the smectite layer create preferential interlayer positions of the [Zr4(OH)12(H2O)12]4+ ion. A regular distribution of the tetrahedral substitutions in the smectite layer results in a better intercalant ordering in the interlayer space. Such a more homogeneous intercalant distribution results in a better interlayer pore size control.

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PubMed2002

Synthesis of a new ion exchanger, zirconium vanadate, and its application to the separation of barium and cesium radionuclides at tracer levels.

A new inorganic ion exchanger, zirconium vanadate, has been synthesized and characterized. Elemental analysis suggests that the probable formula of the compound is ZrO2, V2O5, 2H2O. The exchanger is highly stable in thermal, radiation and chemical environments. Radiochemical separation schemes for the 134Cs and 133Ba pair and also for separating the short-lived daughter 137Ba from its parent 137Cs using this newly synthesized ion exchanger have been developed.

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PubMed2000

Ligand-exchange chromatography at zirconium(IV) immobilized on IDA-type chelating polymer gel

Ligand-exchange chromatography of organo-acidic compounds at Zr(IV) immobilized on IDA-type chelating polymer gel using an aqueous mobile phase was studied, to obtain some insight into their retention on zirconia. Zirconium(IV) has no contribution to the retention of phenols, while appreciably enhancing that of benzoic acids and strongly or occasionally irreversibly adsorbing the potentially chelating substances. The presence of two stationary-phase species adsorbing benzoates was confirmed, and the retention over a wide pH range of 3.5-9.5 was quantitatively formulated. The correlation of the retention factor with the Bronsted acidity of samples and its dependence on pH were theoretically explained, and the performance of this chromatographic system was compared with that of zirconia.

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PubMed2004

Effects of two-phase reactions on composition and potential response of zirconium(IV)-tetraphenylporphyrin complexes as carrier for citrate-selective electrode.

The reactions between zirconium(IV)-tetraphenylporphyrin(tpp)-hydroxide complexes ([ZrIV2(OH)4(tpp)2] and [ZrIV(OH)2(tpp)]) in chlorobenzene and various acids (HX: HClO4, HCl, HNO3, CH3COOH) in water were studied. Three species [ZrIV2(OH)3(tpp)2],X, [ZrIV(OH)X(tpp)], and [ZrIVX2(tpp)] were identified, and their stability constants were determined. The extent of formation of each species depends on the coordination ability and lipophilicity of X-. The performance of these complexes was evaluated as a carrier of an anion-selective electrode. The cationic complex [ZrIV2(OH)3(tpp)2],X exhibited selectivity following the Hofmeister series to weakly coordinating anions, while showing a super-Nernstian response to strongly coordinating citrates. The latter suggests the cleavage of the dimeric structure. The dichloro complex [ZrIVCl2(tpp)] was prone to hydrolyze in contact with an aqueous solution and gave drifting potentials. The monochloro complex [ZrIV(OH)Cl(tpp)] was more stable and strongly responded to acetates, which may be ascribed to substitution of a weakly bound chloride. A slow hydrolysis giving [ZrIV(OH)2(tpp)], however, caused gradual deterioration of this strong response to acetates. Conditioning of the membrane in 1 M HCl regenerated the once-deteriorated carrier [ZrIV(OH)Cl(tpp)], while continuous conditioning extended its operating life. This carrier was effectively used to continuously monitor the acetate in a flow system. The dihydroxo complex [ZrIV(OH)2(tpp)] showed lower responses to common anions due to strong Zr-OH bonding and was thus successfully used for selective potentiometry of citrates.

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PubMed2003

Direct ion exchange of tris(2,2'-bipyridine)ruthenium(II) into an alpha-zirconium phosphate framework.

The first direct ion exchange of a luminescent metal complex into an alpha-zirconium phosphate framework has been accomplished. A hydrated form of alpha-ZrP, with an expanded 10.3 A interlayer distance, has been used for the intercalation of Ru(bpy)(3)(2+), resulting in further expansion to 15.2 A. The Ru(bpy)(3)(2+) luminescence band is slightly blue-shifted. High Ru(bpy)(3)(2+) loadings lead to luminescence self-quenching.

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PubMed2003

Bis(alkylamido)phenylborane complexes of zirconium, hafnium, and vanadium.

The coordination chemistry of the bis(tert-butylamido)phenylborane ligand, [(t)BuN-B(Ph)-N(t)Bu](2)(-), is developed. The ligand can be delivered to metals of groups 4 and 5 from its dilithio salt. The reactions of PhB((t)BuNLi)(2), 1, with metal halides of zirconium, hafnium, and vanadium generate complexes of the general formulas ((t)BuN-B(Ph)-N(t)Bu)(2)M(THF) (M = Zr (2), Hf (3)), Li(2)[M((t)BuN-B(Ph)-N(t)Bu)(3)] (M = Zr (4), Hf (5)), and M((t)BuN-B(Ph)-N(t)Bu)(2) (M = V (6)). (1)H and (11)B[(1)H] NMR and single-crystal X-ray analysis show that these amido metal complexes are structurally analogous to amidinates.

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PubMed2003

A novel zirconium polyoxometalate complex that contains both a coordinated saturated anion, [PMo12O40]3-, and a coordinated unsaturated anion, [PMo11O39]7-.

The novel 8-coordinate zirconium compound (NH(4))(6)[Zr(PMo(12)O(40))(PMo(11)O(39))].26H(2)O (1) has been synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, and vibrational and (31)P NMR spectroscopy. It is the first example of a metal complex containing both parent, [PMo(12)O(40)](3)(-), and monovacant lacunary, [PMo(11)O(39)](7)(-), anions. Furthermore, this is the first crystallographic determination of the [PMo(11)O(39)](7)(-) anion.

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PubMed2003

Synthesis and structural investigation of N,N',N' '-trialkylguanidinato-supported zirconium(IV) complexes.

The addition of 2 equiv of N,N',N' '-triisopropylguanidine (guanH(2)) to Zr(CH(2)Ph)(4) produced the bis(guanidinato)bis(benzyl)zirconium complex [((i)PrNH)C(N(i)Pr)(2)](2)Zr(CH(2)Ph)(2) (1). The mono(guanidinato) complex [((i)PrN)(2)C(NH(i)Pr)]ZrCl(3) (2) was accessible by the reaction of 2 equiv of guanH(2) with ZrCl(4). Guanidinium hydrochloride, [C(NH(i)Pr)(3)]Cl, is a byproduct of this reaction. When crystallized from THF, complex 2 was isolated as the THF adduct [((i)PrNH)C(N(i)Pr)(2)]ZrCl(3)(THF) (2-THF). The mixed cyclopentadienyl guanidinato complex [eta(5)-1,3-(Me(3)Si)(2)C(5)H(3)][((i)PrNH)C(N(i)Pr)(2)]ZrCl(2) (3) was prepared by treatment of [1,3-(Me(3)Si)(2)C(5)H(3)]ZrCl(3) with the in situ generated lithium triisopropylguanidinate salt. The reaction of guanH(2) with [1,3-(Me(3)Si)(2)C(5)H(3)]ZrMe(3) affords the dimethyl derivative [eta(5)-1,3-(Me(3)Si)(2)C(5)H(3)][((i)PrNH)C(N(i)Pr)(2)]ZrMe(2) (4). Definitive evidence for the molecular structures of these products is provided through single-crystal X-ray characterization of 1, 2-THF, and 3, which are presented. The extent of pi delocalization within the guanidinato ligand is discussed in the context of the metrical parameters obtained from these structural studies.

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PubMed2004

Vibrational study of some layered structures based on titanium and zirconium phosphates.

A Raman and infrared study was carried out on layered zirconium and titanium acid phosphates of alpha- and gamma-type, alpha-M[O(3)POH](2).H(2)O and gamma-M[PO(4)][O(2)P(OH)(2)].2H(2)O, respectively. The spectra were initially approached by means of the classical correlation method in the solid state, which accounts for the complexity of the infrared spectra of both species. However, the number of bands and their relative intensity in the Raman spectra suggest a quite total absence of quadrupolar coupling between the vibrating units. So, if interunit coupling is neglected, a molecular approach considering the vibrations of isolated tetrahedral [PO(4)] and octahedral [MO(6)] building blocks can allow an affordable spectroscopic description of the title compounds. Interesting insights on the relationships between spectral properties and structure can be drawn by comparison with the spectra of alkali phosphates and of MO(6) oxoanions. A significant high-energy shift of the nu(P-O) modes is observed in the layered phosphates with respect to the corresponding salts, which parallels the low-energy shift of the nu(M-O) modes. Surprisingly, an increase of the M-OP interaction can reinforce the P-O bond. A simple theoretical model, based on the interaction between the [PO(4)] unit and four Li(+) in similar geometrical arrangement found in the structures of the layered phosphates, offers a reasonable explanation of this phenomenon.

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PubMed2004

Structure and dynamics of dinuclear zirconium(IV) complexes.

We have determined by X-ray crystallography the structures of three dinuclear zirconium(IV) complexes containing the heptadentate ligand dhpta (where H(5)dhpta = 1,3-diamino-2-propanol-N,N,N',N'-tetraacetic acid, 1) and different countercations: K(2)[Zr(2)(dhpta)(2)].5H(2)O (2.5H(2)O), Na(2)[Zr(2)(dhpta)(2)].7H(2)O.C(2)H(5)OH (3.7H(2)O.C(2)H(5)OH), and Cs(2)[Zr(2)(dhpta)(2)].H(5)O(2).Cl.4H(2)O (4.H(5)O(2).Cl.4H(2)O). In the K(I) complex 2, crystallized from water, the two Zr(IV) ions are 3.5973(4) A apart and bridged via two alkoxo groups (average Zr-O 2.165 A). Each Zr(IV) is eight-coordinate and also bound to two N atoms (average Zr-N 2.448 A), and four carboxylate O atoms (average Zr-O 2.148 A). The two dhpta ligands in the dinuclear unit have different conformations. One face of the complex contains an array of 14 oxygen atoms and interacts strongly with the two K(I) ions, one of which is 6-coordinate, the other 8-coordinate, which are 3.922(4) A apart and bridged by a carboxylate O and by two water molecules. The structures of the dinuclear anion [Zr(2)(dhpta)(2)](2-) in the Na(I) complex 3 and in the Cs(I) complex 4 are essentially identical to that found in complex 2, although the alkali metal ions coordinate differently to the oxygen-rich face. All Zr(IV) ions have a distorted triangulated dodecahedral geometry. Although the crystal structure of complex 2 does not indicate the presence of acidic protons, in 4 an [H(5)O(2)](+) unit is strongly H-bonded to an oxygen atom of a coordinated carboxylate group. 1D and 2D (1)H and (13)C NMR spectroscopic and potentiometric studies reveal two deprotonations with pK(a) values of 9.0 and 10.0. At low pH, two carboxylate groups appear to undergo protonation accompanied by chelate ring-opening, and the complex exhibits dynamic fluxional behavior in which the two magnetically nonequivalent dhpta ligands exchange at a rate of 11 s(-1) at pH 3.30, 298 K, as determined from 2D EXSY NMR studies. Ligand interchange is not observed at high pH (>11). The same crystals of complex 2 were obtained from solutions at pH 3 or 12. The dynamic configurational change is therefore mediated by the aqueous solvent.

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PubMed2005

Zirconium and hafnium complexes containing bidentate diarylamido-phosphine ligands.

The first examples of mononuclear, structurally characterized triarylphosphine complexes of zirconium and hafnium are reported. The metathetical reactions of MCl4(THF)2 (M = Zr, Hf) with [iPrNP]Li(THF)2 ([iPrNP]- = N-(2-(diphenylphosphino)phenyl)-2,6-diisopropylanilide) or [MeNP]Li(THF)2 ([MeNP]- = N-(2-(diphenylphosphino)phenyl)-2,6-dimethylanilide) in toluene at -35 degrees C produced the corresponding [iPrNP]MCl3(THF) and [MeNP]2MCl2, respectively, in high yield. In contrast, attempts to prepare [MeNP]MCl3(THF) and [iPrNP]2MCl2 led to the concomitant formation of mono- and bis-ligated complexes, from which purification proved rather ineffective. The solution and solid-state structures of [iPrNP]MCl3(THF) and [MeNP]2MCl2 were studied by multinuclear NMR spectroscopy and X-ray crystallography. The geometry of these six-coordinate complexes is best described as a distorted octahedron in which the chloride ligands in [iPrNP]MCl3(THF) adopt a virtually meridional coordination mode whereas those in [MeNP]2MCl2 are trans to each other.

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PubMed2006

Synthesis and structure of asymmetric zirconium-substituted silicotungstates, [Zr6O2(OH)4(H2O)3(beta-SiW10O37)3]14- and [Zr4O2(OH)2(H2O)4(beta-SiW10O37)2]10-.

The reaction of ZrCl4 with [gamma-SiW10O36]8- in a potassium acetate buffer results in two different products depending on the reactant ratios. The trimeric species [Zr6O2(OH)4(H2O)3(beta-SiW10O37)3]14- (1) consists of three beta23-SiW10O37 units linked by an unprecedented Zr6O2(OH)4(H2O)3 cluster with C1 point group symmetry. The dimeric species [Zr4O2(OH)2(H2O)4(beta-SiW10O37)2]10- (2) consists of beta22- and beta12-SiW10O37 units sandwiching a Zr4O2(OH)2(H2O)4 cluster, which also has C1 symmetry. Polyanion 1 contains more zirconium centers than any other polyoxometalate known to date.

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PubMed2006

New architectures for zirconium polyphosphonates with a tailor-made open-framework structure.

The use of tetraphosphonic building blocks for the preparation of inorganic-organic zirconium derivatives has led to the formation of novel compounds with a modular structure. This is based on the different connection of polymeric 1D inorganic units covalently connected by organic groups. The different kinds of connections generate two different open-framework structures. These structures have been solved "ab initio" by powder X-ray diffraction data. Very likely, the dimensions of the channels inside these structures may be tuned by the right choice of the interlinking organic group.

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PubMed2006

Titanium(IV) and Zirconium(IV) amido complexes derived from the azaoxa macrocycle 3,3-dimethyl-1,5-diaza-8-oxacyclodecane.

The novel tridentate azaoxa macrocycle [O(NH)2], 3,3-dimethyl-1,5-diaza-8-oxacyclodecane, can be singly or doubly lithiated with (n)BuLi at the secondary amine N atoms, giving [O(NH)N]Li and [O(N)2]Li2, respectively, and further elaborated with introduction of TMS substituents via reaction with (TMS)Cl. Aminolysis of [Ti(NMe2)2Cl2] or [Zr(NR2)2Cl2(THF)2] with [O(NH)2] in toluene gave the distorted octahedral M[O(NH)N](NR2)Cl2 (M = Ti, R = Me; M = Zr, R = Me or Et), in which the macrocycle functions as a monoanionic ligand via an amido, an amine, and an ether functionality. Salt metathesis of [Zr(NEt2)2Cl2(THF)2] with [O(NH)N]Li in toluene afforded Zr[(O(NH)N)](NEt2)2Cl, the structure of which also confirms tridentate macrocycle coordination via one amido, one amine, and one ether group; in contrast, analogous salt metathesis involving [Zr(NEt2)2Cl2(THF)2] and [O(N)2Li2] gave the "sandwich" complex [(ON2)2Zr], with the macrocycle behaving as a dianionic ligand (Porter, R. M.; et al. Dalton Trans. 2005, 427). Finally, treatment of [O(NH)2] with AlMe3 gave the simple donor-acceptor adduct [O(NH)2]AlMe3, which resisted alkanolysis by prolonged heating. In the presence of MAO the new zirconium, titanium, and aluminum complexes show low activity in the polymerization of ethylene.

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PubMed1996

The First Mixed-Halide Zirconium Cluster Compounds: Zr(6)Cl(1.6)I(10.4)Be, Zr(6)Cl(1.3)I(10.7)B, and Zr(6)Cl(11.5)I(1.5)B. Matrix Effects and Halogen Substitution in Compact Network Structures.

Investigations of the effect of halogen size on structure stability have been conducted in well-reduced and heavily interbridged zirconium chloride-iodide cluster systems. The title compounds are obtained in good yields from reactions of Zr, ZrCl(4), ZrI(4), and B or Be in sealed Ta tubes for approximately 4 weeks at 850 degrees C. Single-crystal diffraction at room temperature established these as Zr(6)Cl(1.65(4))I(10.35(4))Be and Zr(6)Cl(1.27(3))I(10.73(3))B [R&thremacr;, Z = 3, a = 14.3508(8), 14.389(1) Å, c = 9.8777(9), 9.915(2) Å, respectively] and Zr(6)Cl(11.47(2))I(1.53(2))B [P4(2)/mnm, Z = 2, a = 12.030(1) Å, c = 7.4991(8) Å]. These are derivatives of the Zr(6)I(12)C and orthorhombic Zr(6)Cl(13)B structures, respectively, the latter containing unusual linear chains of clusters interbridged by Cl(i-i) that are in turn interconnected by three-bonded Cl(a-a-a) atoms. The random substitution of fractional Cl at specific I sites in the first two, and I for certain Cl in the third, was positionally resolved in all cases. The replacement always occurs at two-bonded X(i), so that single types of halogen are left in sites that interconnect clusters and generate the three-dimensional array. Structural changes seen in both structures are specifically related to relief of X.X crowding in the parent structure (matrix effects). Substitution of Cl for I(i) in the Zr(6)I(12)C type greatly reduces intercluster I.I repulsions and allows, among other things, a 0.20 Å (5.8%) reduction in Zr-I(a-i) intercluster bond lengths. Increased Cl.I repulsions caused by I substitution in orthorhombic Zr(6)Cl(13)B (Pnnm) convert the twisted chains and angular Cl(a-a-a) interchain bridges to planarity in tetragonal Zr(6)Cl(11.5)I(1.5)B. Phase widths found are 0 </= x </= 1.4 for Zr(6)Cl(x)()I(12)(-)(x)()Z (Z = B, Be) and 0 </= x </= 1.5 for Zr(6)Cl(13)(-)(x)()I(x)()B. The limit for iodine substitution in the chlorine-rich rhombohedral Zr(6)Cl(12)(-)(x)()I(x)()Be is about x = 2.5.

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PubMed1996

Five- and Six-Coordinate 2-Methyl-2-propanethiolato Complexes of Zirconium(IV): Synthesis and Structures of [Li(DME)(3)][Zr(SCMe(3))(5)] and [(THF)Li](2)Zr(SCMe(3))(6).

Five-coordinate and six-coordinate 2-methyl-2-propanethiolato complexes of zirconium, [Li(DME)(3)][Zr(SCMe(3))(5)] (1) and [(THF)Li](2)Zr(SCMe(3))(6) (2), were obtained from the ZrCl(4)/LiSCMe(3) reaction system. The control of the Zr coordination number, by the ether ligands, THF or DME, bound to Li, is demonstrated by the conversion of 2 into 1 upon dissolution in DME. 1 and 2 were crystallographically characterized. The structures are extensively disordered. Crystal data follow: 1, hexagonal P6(3)/m, a = b = 12.496(3) Å, c = 17.561(9) Å, Z = 2, V = 2375(1) Å(3), R = 5.0%, R(w) = 6.8%; 2, trigonal R32, a = b = 11.813(3) Å, c = 28.37(1) Å, Z = 3, V = 3428(1) Å(3), R = 5.2%, R(w) = 6.4%.

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PubMed1996

Organometallic Fluorides of Zirconium and Hafnium in the Synthesis of Carboxylate Complexes: Molecular Structures of [{(eta(5)-C(5)Me(5))ZrF(OCOCF(3))(2)}(2)] and [(eta(5)-C(5)Me(5))(2)Zr(OCOCF(3))(2)].

The reaction of [(eta(5)-C(5)Me(5))ZrF(3)] and [(eta(5)-C(5)Me(5))HfF(3)] with Me(3)SiOCOCF(3) yields the dinuclear complexes [{(eta(5)-C(5)Me(5))ZrF(OCOCF(3))(2)}(2)] (1) and [{(eta(5)-C(5)Me(5))HfF(OCOCF(3))(2)}(2)] (2), regardless of the molar ratio employed. [(eta(5)-C(5)Me(5))(2)ZrF(2)] reacts with 1 and 2 equiv of Me(3)SiOCOCF(3) to form the mononuclear compounds [(eta(5)-C(5)Me(5))(2)Zr(OCOCF(3))(2)] (3) and [(eta(5)-C(5)Me(5))(2)ZrF(OCOCF(3))] (4), respectively. The molecular structures of 1 and 3 have been determined by single-crystal X-ray analysis: 1, triclinic, P&onemacr;, a = 9.508(3) Å, b = 11.002(4) Å, c = 17.528(3) Å, alpha = 78.55(4), beta = 76.80(2), gamma = 87.51(2) degrees, V = 1750(1) Å(3), Z = 2, R = 0.0378; 3, monoclinic, C2/c, a = 18.553(4) Å, b = 9.110(2) Å, c = 16.323(3) Å, beta = 114.88(3) degrees, V = 2503(1) Å(3), Z = 4, R = 0.0457. Compound 1 shows bridging bidentate and chelating carboxylate ligands as well as bridging fluorine atoms. The zirconium atoms are seven coordinated and have an 18-electron configuration. X-ray studies of 3 reveal two structural components where the carboxylate ligands coordinate in a monodentate (major component) and a chelating manner (minor component).

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