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A monoanionic bidentate [PN]‐type ligand based on dibenzophosphole was synthesized, and its coordination properties toward titanium and zirconium were investigated. The complexes [PN]M (NR2)3 (M = Ti, R = Me; M = Zr, R = Et) were synthesized through the reaction of 4‐(1H‐pyrrole‐2‐yl)dibenzophosphole, [PN]H, with three equivalents of Ti (NMe2)4 or Zr (NEt2)4. Both titanium and zirconium complexes featuring the [PN] ligand were characterized by NMR and elemental analysis. Single‐crystal X‐ray crystallography unveiled the solid‐state structure of [PN]Zr (NEt2)3, with the pyrrolido group coordinated to the zirconium center in the η1‐mode. Ethylene polymerization at 0.4 MPa using these complexes and dried modified methylaluminoxane (dMMAO) as a cocatalyst yielded linear polyethylene (PE) with a melting point of 128°C–136°C; the polymerization activity reached up to 64 kg/mol (Zr)·h·bar at 70°C. [ABSTRACT FROM AUTHOR]

Constrained geometry complexes (CGCs) are homogeneous olefin polymerization catalysts that have been improved because of their considerably high activity and their copolymerization abilities for ethylene with α‐olefins. The ancillary ligands in CGCs comprise bridged 6π‐electron moieties (e.g., cyclopentadienyl (Cp) and fluorenyl) and amide donors. In this study, we investigated the effect of changing the 6π‐electron moieties to a diphenylmethyl moiety (Ph2C) on the polymerization activity of [Me2Si(Ph2C)(tBuN)]ZrCl2(thf) (thf = tetrahydrofuran). We synthesized [Me2Si(Ph2C)(tBuN)]ZrCl2(thf) and characterized it via 1H nuclear magnetic resonance analysis and single‐crystal X‐ray crystallography. Ethylene polymerization at 2 MPa using a catalyst of the [Me2Si(Ph2C)(tBuN)]ZrCl2(thf) and modified methylaluminoxane (MMAO) as a cocatalyst yielded a linear polyethylene (PE) with a high melting point (124°C–134°C); moreover, the polymerization activity of the catalyst was found to be up to 445 g (PE) mmol (Zr)−1 h−1. The polymerization of styrene using the zirconium complex and MAOs did not proceed, but the polymerization of 1,3‐butadiene produced a small amount of polybutadiene with ~60% cis‐1,4‐structure. These results indicate that non‐Cp‐type CGCs, which can be defined as metal complexes bearing an ancillary ligand in which non‐Cp moieties (benzyl moiety in this study) and an amido group are bridged by an organic linker, can become a new family of homogeneous olefin polymerization catalysts. [ABSTRACT FROM AUTHOR]

• A novel zirconium complex was synthesized under solvothermal system. • The crystals of zirconium complex exhibit blue luminescence. • The zirconium complex is highly selective and sensitive to detection of Co2+ ions. A novel blue emission of zirconium complex, formulated as [Zr(pydc) 3 ]·[(CH 3) 2 NH 2 ] 2 (1), has been synthesized by using a mixture of zirconium nitrate and 2, 6-pyridinedicarboxylic acid (H 2 pydc). The complex 1 presents a three-dimensional supramolecular network structure due to the intermolecular N H···O, O H···O hydrogen bonds. Additionally, the crystals of 1 exhibit blue luminescence and demonstrate a highly selective and sensitive sensing capability for detection of Co2+ ions with a K sv value of 1.22 × 104 M−1 and limit of detection (LOD) of 1.20 × 10−5 M. Furthermore, the fluorescence lifetime and quantum yield of the complex 1 is τ = 6.22 μs and Φ = 25.9 %. a novel blue emission of zirconium complex has been synthesized with s elective and sensitive sensing capability for detection of Co2+ ion. [Display omitted] [ABSTRACT FROM AUTHOR]

Salicylaldehyde imine ligands (1, 2) and corresponding salicylaldiminato zirconium complexes (3, 4) were prepared via the condensation reaction by using 3-tert-butyl-5-methoxy salicylaldehyde and ortho-substituted anilines as the materials. Both ligands and complexes were characterized by mass spectrum, 1H-NMR and 13C-NMR spectroscopy. In the presence of methylaluminoxane (MAO) as a co-catalyst, both zirconium complexes exhibited good catalytic activity for ethylene polymerization in toluene, producing ultra high molecular weight polyethylene (UHMWPE). Complex 3 was found to exhibit the activity of 50.2 kg/(mmol·h) at 50℃ and 0.9 MPa pressure in toluene, resulting in UHMWPE with a viscosity average molecular weight value of 1.5×106. In case of complex 4, the activity increased from 45.5 kg/(mmol·h) at 17℃ to 55.6 kg/(mmol·h) at 50℃. An obvious decrease of activity could be observed when the temperature was above 50℃. This decrease was probably due to the decomposition of active species at high temperature. High nAl:nZr ratio led to an enhancement in activity and a decrease in molecular weight, which could be ascribed to the more active species and higher chain transfer rate in the catalytic system. In addition, complex 4 showed higher ethylene polymerization activity of 60.2 kg/(mmol·h) at 30℃ and 0.9 MPa when n-hexane was employed as the solvent, affording the polyethylene with a viscosity average molecular weight value up to 6.6×106. The rheometer analysis of polymer generated from complex 4 revealed a narrow molecular weight distribution 2.4, indicating a well-controlled manner during the polymerization process. Characteristic absorption appearing at 1 471 cm-1 and 719 cm-1 from infrared spectrum proved that the microstructure of UHMWPE sample was linear. The high melting points of obtained polymers measured by Differential Scanning Calorimetry (DSC), ranging from 138℃ to 140℃, were typical for linear polyethylene. [ABSTRACT FROM AUTHOR]

A series of new fluorenylamido-ligated zirconium complexes bearing an electron-donating adamantyl group on the amido ligand were synthesized and characterized by elemental analysis, 1H NMR, and single crystal X-ray analysis. The coordination mode of the fluorenyl ligand to the zirconium metal was η3 manner, and all the complexes were Cs-symmetric in solution. The complexes showed moderate activity (1.0 × 105 g-polymer mol-Zr-1·h-1), even at a low Al/Zr ratio of 50. The increase of propylene pressure improved the activity by one order of magnitude (up to 1.0 × 106 g-polymer mol-Ti-1·h-1). All catalyst systems gave syndiotactic polypropylene, where the complex containing the 3,6-di-t-butyl fluorenyl ligand was more effective for the enhancement of the syndiospecificity. The increase of propylene pressure also improved the syndiospecificity with the syndiotactic pentad of 0.96 and the melting point of 159 °C. [ABSTRACT FROM AUTHOR]

There are two independent molecules in the asymmetric unit of the title compound, [Zr(C18H24N3Si)Cl3(C7H5N)], which are connected by an N—H...Cl hydrogen bond. The Zr atoms are seven-coordinate and possess a distorted pentagonal–bipyramidal geometry. In the crystal, molecules are connected by N—H...Cl hydrogen bonds, forming ribbons along [010].

Abstract: The titanium and zirconium complexes based on thioether substituted β-carbonylenamine were prepared and characterized. In the presence of MMAO, the titanium complexes showed good activity in syndiospecific styrene polymerization with high syndioselectivity, and performed good thermal stability. Electron withdrawing group on ligands is beneficial to the styrene polymerization. [1,3-diphenyl-3-(2-(isopropylthio)ethylimino)prop-1-en-1-olate]2ZrCl2(IV) could also polymerize styrene to give syndiotactic polymer, however in low activity and with low syndioselectivity. [Copyright &y& Elsevier]

Abstract: Groundwater is a very important component of water resources in coastal aquifers in Thoothukudi. It has been established that the groundwaters in the coastal zone of the Zirconium Complex, Pazhayakayal, Thoothukudi district, Tamilnadu, India, are subjected to wave and tidal impact. The groundwater quality was studied by hydrogeological methods, 2D electrical resistivity imaging (ERI) techniques (six profiles), 11 Wenner vertical electrical sounding (VES), and well log analysis. Also, nine geochemical water samples were taken from the study area. The 2D ERI and VES surveys were carried out using WGMD-4 Ltd., Chennai, resistivity meter, multicore cable, and multielectrodes with Wenner array. The collected resistivity data were interpreted using the Res2DINV software. The research shows that the groundwaters are the result of the paleoriver flow along the Tamirabarani Channel in the western area and of the seawater intrusion in the eastern area. The fresh water is characterized by resistivity of about 10–100 Ohm⋅m in the study area. The resistivity of 10–50 Ohm⋅m indicates that the subsurface section is made up of sand, clay, and caliche. Resistivity values of more than 200 Ohm⋅m are specific to sand dunes. The very low resistivity (<5 Ohm⋅m) layer might be due to the seawater intrusion in the study area. Six water samples from the well drilled in the coastal area were analyzed, which made it possible to determine the concentrations of major and trace elements in the groundwaters. These data were used to establish the seawater intrusion and coastal environment characteristics in the study area. [Copyright &y& Elsevier]

The construction and evaluation of a novel modified carbon paste electrode with high selectivity toward oxalate ion are described. The constructed carbon paste potentiometric sensor for oxalate ion is based on the use of a zirconium salan complex as a good ionophore in the carbon paste matrix. The electrode exhibits a Nernstian slope of 29.1mV/decade to oxalate ion over a wide concentration range from 1.5×10−6 to 3.9 ×10−2 molL−1 with a low detection limit of 7.0×10−7 molL−1. The electrode possesses fast response time, satisfactory reproducibility, appropriate lifetime, and most importantly, good selectivity toward C2O4 2− relative to a variety of common anions. The potentiometric response of the electrode is independent of the pH of the test solution in the pH range 2.5–8.0. The modified carbon paste electrode was successfully applied as an indicator electrode in potentiometric titration and potentiometric determination of oxalate ion in mineral water, blood serum and urine samples. [ABSTRACT FROM AUTHOR]

Abstract: A new zirconium complex containing amidinate, guanidinate and amide ligand sets with formula Zr[(CyN)2CMe][(CyN)2CNMe2](NMe2)2 (1) (Cy=cyclohexyl) was synthesized by the insertion of the 1,3-dicyclohexylcarbodiimide moiety into the bond of zirconium and dimethylamido group. Characterization of the complex 1 was achieved using elemental analysis, 1H and 13C NMR spectra and single crystal X-ray diffraction. The molecular structure of the complex 1 revealed that the coordination geometry around the zirconium is a distorted pseudo-octahedron. The metal center is surrounded by the four nitrogen atoms of two bidentate amidinate and guanidinate ligands positioned cis to each other and two cis-NMe2 groups. [Copyright &y& Elsevier]

[t-BuNSiMe2(2,7-t-Bu2Flu)]ZrMe2 and [t-BuNSiMe2(3,6-t-Bu2Flu)]ZrMe2 were synthesized, and the solid structure of complex [t-BuNSiMe2(2,7-t-2Flu)]ZrMe2 was elucidated by single crystal X-ray analysis. These complexes were applied for propylene polymerization using dried modified methylaluminoxane as a cocatalyst at 0°C and 20°C in toluene. Both systems did not show activity at 0°C, but they conducted the polymerization at 20°C. The introduction of t-butyl substituents to the fluorenyl ligand improved the activity more than six times regardless of the position of the substituents, and both systems gave low molecular weight polypropylenes (PP) with narrow molecular weight distribution. The introduction of t-butyl substituents also improved the syndiospecificity and [t-BuNSiMe2(3,6-t-Bu2Flu)]ZrMe2 gave highly syndiotactic PP with the syndiotactic pentad of 0.91 and the melting point of 145°C. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis and characterization of the new, 16 electron half-open zirconocenes, Zr(C5H5)(c-C8H11)(PR3) (R=Me, Et) are reported, together with a structural study of the PEt3 complex. As with other low valent half-open zirconocenes, the Zr–C distances are significantly shorter on average for the electronically open dienyl ligand than those for the C5H5 ligand, 2.343 vs. 2.512Å. Reaction of either of these compounds with PhC2Ph led to the incorporation of two equivalents of the alkyne, resulting in a formally 14 electron complex with coordination from cyclopentadienyl, allyl, σ-alkyl, and σ-vinyl units. [Copyright &y& Elsevier]

Treatment of the different kinds of alkynyl-substituted dialkynyldiarylsilanes with zirconocene–ethylene complex Cp2Zr(CH2CH2) followed by acidification with 3 N HCl gave regio- and stereoselectively the corresponding silacyclobutenes in good yields. Desilylation of the silacyclobutenes with tetrabutylammonium fluoride afforded stereoselectively unsymmetrical conjugated (1E,3E)-dienes and -trienes (R1 or R2 = 1-cyclohexenyl) in excellent yields. [Copyright &y& Elsevier]

Abstract: A new alizarin based azacrown ether N-(alizarin-4-methylene)-4-azadibenzo-18-crown-6 (AMADCE) was synthesized, for the transportation of fluoride ions, by reacting 4-aza dibenzo 18-crown-6 with alizarin in the presence of formaldehyde. The compound forms a stable purple-red coloured complex with Zr(IV) in 0.5–1.0M hydrochloric acid and gets quantitatively extracted into diphenyl ether. This diphenyl ether extract of the Zr(IV) complex instantaneously transfers fluoride ions from the aqueous phase, which was utilised for the sensitive determination and transportation of fluoride ions through the liquid membrane. The conditions like concentration of membrane phase, acidity of the source phase and the receiving phase, and the transportation time were optimized. The continuous transportation of fluoride ions was achieved by adding receptor ions like La3+ and Ca2+ in the receiving phase. The rate constant K and t 1/2 for the transportation were determined. The studies were extended for the removal of fluoride ions through the liquid membrane from the ground water samples and industrial effluent. [Copyright &y& Elsevier]

Abstract: A general solution to the preparation of pincer complexes that require the formation of two N-heterocyclic carbenes (NHC’s) and the activation of an aryl C–H bond is reported. The reaction of a phenylene-bridged bis(imidazolium) salt with Zr(NMe2)4 generated the requisite CCC–NHC Zr pincer complex, which has been characterized by X-ray crystallography. Subsequent manipulation of the Zr coordination sphere by reaction with MeI demonstrated the robustness of the ligand geometry at Zr and led to the isolation and structural characterization of a CCC–NHC Zr triiodide pincer complex. A variation of the methodology has been applied to a saturated NHC analog to produce the corresponding CCC–NHC Zr pincer complex. Importantly, it has been found that CCC–NHC Zr pincer complexes can be generated in situ and transmetallated with an appropriate Rh source to generate CCC–NHC Rh pincer structures. These two methodologies, metallation of CCC–NHC precursors with transition metal amido complexes combined with transmetallation, hold great promise for opening general synthetic pathways to a wide variety of transition metal CCC–NHC pincer complexes. [Copyright &y& Elsevier]

The reactions of Zr(C5H5)(6,6-dmch)(PMe3)2 and Zr(6,6-dmch)2(PMe3)2 (dmch=dimethylcyclohexadienyl) with CO lead to the selective replacement of one PMe3 ligand by CO. Both carbonyl complexes have been structurally characterized. Additionally, the reaction of the latter complex with PhC2SiMe3 leads to a similar replacement of one PMe3 ligand, involving simple coordination of the alkyne, rather than any coupling to the dmch ligand. [Copyright &y& Elsevier]

Treatment of LZrCl2 (L=N,N′-ethylenebis(3,5-di-tert-butylsalicylideneiminato) (1), N,N′-o-phenylenebis(3,5-di-tert-butylsalicylideneiminato) (2)), which is an effective catalyst precursor for ethylene oligomerization, with 1.5 equiv of water in toluene afforded H2O-coordinating salen-type zirconium complexes [LZrCl2(H2O)]. The effects of the content of H2O and the temperature on the equilibrium of association and disassociation of H2O molecule in [LZrCl2(H2O)n] (n=0, 1) were studied in solution (CDCl3) by 1H NMR spectroscopy. The crystal and molecular structure of [1(H2O)] was determined by X-ray diffraction analysis, which revealed that a herringbone supramolecular assembly was constructed in the crystalline state of [1(H2O)], stacked by the intermolecular hydrogen bonds between the OH group of the coordinating H2O and one of the chloride ligands. [Copyright &y& Elsevier]

Glassy residues of the complex bis(N,N′-disalicylidene-1,2-phenylenediamino)zirconium(IV), Zr(dsp), on glass slides were exposed to atomic oxygen in a plasma asher or an atomic beam facility for various amounts of lime in order to study the erosion process, determine the rate of erosion, and learn the chemical identity of the residue. The exposed films were characterized by weight loss, optical photography, profilometry, diffuse reflectance and total transmittance spectroscopy, scanning electron microscopy (SEM) with wavelength dispersive X-ray spectrometry (WDS), X-ray diffraction, and X-ray photoelectron spectroscopy (XPS). Results indicate that these films erode much more slowly polyimide (Kapton™) film under identical conditions, that the erosion is very nonuniform, and that zirconium dioxide is the predominant product after extended exposure. This complex is currently being evaluated as a polymer additive. [ABSTRACT FROM AUTHOR]

Amino acid complexes of zirconia represent an entirely new class of materials that were synthesized and studied for the first time for the decontamination of fluoride ion containing aqueous solutions. Glutamic and aspartic acid complexes of zirconia assembled with thin carbon (stacked graphene oxide) platelets deriving from graphite oxide (GO) were synthesized by a two-step method to prepare adsorbents. The characterization of the complexes was carried out using infrared spectroscopy to determine the functional groups and the types of interaction between the composites and fluoride ions. To reveal the mechanisms and extent of adsorption, two types of batch adsorption measurements were performed: (i) varying equilibrium fluoride ion concentrations to construct adsorption isotherms at pH = 7 in the absence of added electrolytes and (ii) using fixed initial fluoride ion concentrations (10 mg/L) with a variation of either the pH or the concentration of a series of salts that potentially interfere with adsorption. The experimental adsorption isotherms were fitted by three different theoretical isotherm equations, and they are described most appropriately by the two-site Langmuir model for both adsorbents. The adsorption capacities of Zr-glutamic acid-graphite oxide and Zr-aspartic acid-graphite oxide are 105.3 and 101.0 mg/g, respectively. We found that two distinct binding modes are combined in the Zr-amino acid complexes: at low solution concentrations, F - ions are preferentially adsorbed by coordinating to the surface Zr species up to a capacity of ca. 10 mg/g. At higher concentrations, however, large amounts of fluoride ions may undergo anion exchange processes and physisorption may occur on the positively charged ammonium moieties of the interfacially bound amino acid molecules. The high adsorption capacity and affinity of the studied dicarboxylate-type amino acids demonstrate that amino acid complexes of zirconia are highly variable materials for the safe and efficient capture of strong Lewis base-type ions such as fluoride.

Abstract: Porous zirconium complex-layered titanate nanohybrids were synthesized by reassembling reaction between negative-charged layered titanate nanosheets and positive-charged zirconium complex. According to powder X-ray diffraction and electron microscopy, titanate monolayers were interstratified with zirconium species with the repeating unit of ~1.2nm. X-ray absorption spectroscopy at Zr K-edge and Ti K-edge clearly demonstrated that mononuclear zirconium complex was intercalated into lepidocrocite-structured titanate layers. From N2 adsorption–desorption isotherm measurement, the hybridization reaction produced highly porous material with the expanded surface area of ~176 m2g−1. The zirconium complex-layered titanate nanohybrids showed functionalities not only for adsorption of CO2 gas but also for photodegradation of organic molecules. This finding underscored that the reassembling of layered metal oxide with zirconium ions provides powerful ways to synthesize highly porous materials applicable for gas adsorbents and photocatalysts. [Copyright &y& Elsevier]

Abstract: A novel non-symmetric zirconium guanidinato complex, [{Zr{ArNC(NMe2)N(SiMe3)}(μ2-Cl)Cl2}2] (Ar=2,6-iPr2-C6H3), was synthesized and structurally characterized. Catalytic studies showed that the zirconium complex was active for ethylene polymerization with the activity of 4.98×105 g PE/mol Zr h. The influences of cocatalysts, Al/Zr molar ratios and ethylene pressures on the activities were investigated. [Copyright &y& Elsevier]