Synthesis and characterization of 2-hydroxy-pyridine modified Group 4 alkoxides

The reaction of Group 4 metal alkoxides ([M(OR)₄]) with the potentially bidentate ligand, 2-hydroxy-pyridine (2-HO-(NC₅H₄) or H-PyO), led to the isolation of a family of compounds. The products isolated from the reaction of [M(OR)₄] [where M = Ti, Zr, or Hf; OR = OPrⁱ (OCH(CH₃)₂), OBu^t (OC(CH₃)₃), or ONep (OCH₂C(CH₃)₃] under a variety of stoichiometries with H-PyO were identified by single crystal X-ray diffraction as [(OPrⁱ)₂(PyO-κ²(O,N))Ti(μ-OPrⁱ)]₂ (1), [(ONep)₂Ti(μ(O)-PyO-κ²(O,N))₂(μ-ONep)Ti(ONep)₃] (2), [(ONep)₂Ti(μ(O)-PyO-κ²(O,N))(η¹(N),μ(O)-PyO)(μ-O)Ti(ONep)₂]₂ (2a), [H][(PyO-κ²(O,N))(η¹(O)-PyO)Ti(ONep)₃] (3), [(OR)₂Zr(μ(O)-PyO-κ²(O,N))₂(μ-OR)Zr(OR)₃] (OR = OBu^t (4), ONep (5)), [(OR)₂Zr(μ(O,N)-PyO-κ²(O,N))₂(μ(O,N)-PyO)Zr(OR)₃] (OR = OBu^t (6), ONep (7)), [[(OBu^t)₂Zr(μ(O)-PyO-(κ²(N,O))(μ(O,N)-PyO)₂Zr(OBu^t)](μ₃-O)]₂ (6a), [[(ONep)(PyO-κ²(N,O))Zr(μ(O,N)-PyO-κ²(N,O))₂(μ(O)-PyO-κ²(N,O))Zr(ONep)](μ₃-O)]₂ (7a), [(OBu^t)(PyO-κ²(O,N))Zr(μ(O)-PyO-κ²(O,N))₂((μ(O,N)-PyO)Zr(OBu^t)₃] (8), [(OBu^t)₂Hf(μ(O)-PyO-κ²(N,O))₂(μ-OBu^t)Hf(OBu^t)₃] (9), [(OR)₂ M(μ(O)-PyO-κ²(N,O))₂(μ(O,N)-PyO)M(OR)₃] (OR = OBu^t (10), ONep (11)), and [(ONep)₃Hf(μ-ONep)(η¹(N),μ(O)-PyO)]₂Hf(ONep)₂ (12)·tol. The structural diversity of the binding modes of the PyO led to a number of novel structure types in comparison to other pyridine alkoxy derivatives. The majority of compounds adopt a dinuclear arrangement (1, 2, 4–11) but oxo-based tetra- (2a and 7a), tri- (12), and monomers (3) were observed as well. Compounds 1–12 were further characterized using a variety of analytical techniques including Fourier Transform Infrared Spectroscopy, elemental analysis, and multinuclear NMR spectroscopy.     

Synthesis,characterization, and coordination chemistry of the 2-azaphenalenyl radical

The 2-azaphenalenyl radical 2 has been synthesized and characterized by ESR spectroscopy. Variable-temperature ESR measurements were carried out on both the phenalenyl (1) and the 2-azaphenalenyl (2) radicals. The phenalenyl radical 1 has the known propensity to dimerize at temperatures below 20 degrees C, but unexpectedly less so than originally reported. The first experimental measurement of bond dissociation enthalpy for the dimerization of the phenalenyl radical 1 was obtained in CCl(4) (11.34 +/- 0.11 kcal/mol) and toluene (9.8 +/- 0.7 kcal/mol). The 2-azaphenalenyl radical 2 does not show a propensity to dimerize over the measurable temperature range (220-330 K), but does so in the presence of Cu(hfac)(2) (hfac = hexafluoroacetylacetonate). The latter complex was characterized by X-ray crystallography.     

Synthesis and structural characterization of sulfonates, phosphinates and carboxylates of organometallic Group 4 metal fluorides

Reaction of [Cp^*TiF₃] (Cp^* = (ν⁵-C₅Me₅)) with Me₃SiOSO₂- p-C₆H₄CH₃, Me₃SiOPOPh₂ and 1,2-(Me₃SiOCO)₂C₆H₄ yields the dinuclear complexes [{Cp^*TiF(μ-F)(μ-OSO₂-p-C₆H₄CH₄)}₂] (1), [{Cp^*TiF(μ-F)(μ-OPOPh₂)}₂] (2) and [{Cp^*TiF(μ-F)(μ-OCO-o-C₆H₄CO₂SiMe₃)}₂] (3). The molecular structures of 1 and 2 have been determined by single-crystal X-ray analysis. In complexes 1-3, the two titanium atoms are connected by bridging fluorine atoms as well as bridging sulfonate, phosphinate and carboxylate groups respectively. Each titanium atom is also bonded to a terminal fluorine atom. Reaction of [Cp₂^*ZrF₂] with 1,2-(Me₃SiOCO)₂C₆H₄ leads to the mononuclear pentacoordinate 18-electron species [Cp₂^*ZrF(μ-OCO-o-C₆H₄CO₂SiMe₃)] (4) and its structure was determined by X-ray crystallographic methods.     

Group 4 metallocenes in bioorganometallic chemistry

Group 4 metallocene complexes can form adducts or condensation products with a variety of typical biogenic molecules. In this account, examples are presented and discussed for the reactions of zirconocene or titanocene complexes with suitably protected/deprotected carbohydrate derivatives. Some methodological developments are shown for the attachment of aminoacid or peptide derived functional groups at the Cp-rings of the Group 4 bent metallocenes. Eventually, the reactions of methylzirconocene- and methyltitanocene cations with a series of short oligopeptides are discussed that lead to the formation of primary κO-adducts followed by O,N,O-chelate complex formation with methane evolution. The dynamic features of some such systems are discussed.     

Group 4 complexes bearing bis(salphen) ligands: Synthesis,characterization, and polymerization studies

Six different complexes containing bis(salphen) [salphen = N,N'‐phenylenebis(salicylideneimine)] ligands were synthesized and characterized by various spectroscopic techniques and elemental analysis. In the presence of benzyl alcohol as an initiator, all the complexes catalyze the ring‐opening polymerization of lactide and ε‐caprolactone, generating high molecular weight (M_n) polymers in a controlled fashion. The linear relationship between the % conversion and M_n proved the control over the polymerization process. The presence of OBn group as an end group was confirmed by MALDI‐TOF and ¹H NMR spectral analysis of low M_n oligomers. The polymerization followed first‐order kinetics as revealed by kinetic experiments. All the complexes were good precatalysts for the polymerization of ethylene. The effect of temperature and time on the yield and activity toward the polymerization of ethylene were widely investigated. In addition, in the presence of tetrabutylammonium bromide as cocatalyst, the formation of degradable polycarbonate with moderate M_n value and narrow molecular weight distributions was observed by the copolymerization of cyclohexene oxide with CO₂. The effect of initiator structure, temperature, CO₂ pressure, catalyst/cocatalyst loading on the activity, and selectivity toward copolymerization were systematically examined. The thermal properties of the copolymer synthesized were explored using differential scanning calorimetric and thermogravimetric analysis. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 809–824     

Synthesis,characterization and application of soluble fullerenated polymer materials

This article only deals with the topic of intense interest to us and to a considerable extent of our own experimental results on the synthesis,characterization and application of C60-con-taining functional polymers such as poly(N-vinylcarbazole),polystyrene and polyacrylonitrile-based fullerene polymers.The results demonstrate that [60] fullerene can be directly incorporated into a variety of functional polymers by copolymer-ization or grafting,but also can be used to modify or improve the electronic,optical and physicochemical properties of polymers.Both the stereo-electroniceffect and the steric hindrance of C60 have an important influence on the structure and physicochemical properties of the parent polymer.     

Synthesis, characterization, and coordination chemistry of several novel electroneutral phosphane ligands

The reaction of fluorocarbon (R_f) reagents C₂F₅Li or C₂F₃Li with diaminochlorophosphanes (R₂N)₂PCl produced four new phosphane ligands of the type (R₂N)₂P(R_f). Addition of (Et₂N)₂PCl to ethereal solutions of C₂F₅Li or C₂F₃Li produced (Et₂N)₂PC₂F₅1 and (Et₂N)₂PC₂F₃2; treatment of (C₄H₄N)₂PCl and (C₄H₈N)₂PCl with C₂F₅Li afforded (C₄H₄N)₂PC₂F₅3 and (C₄H₈N)₂PC₂F₅4. All ligands were isolated as colorless, high-boiling liquids. Substitution reactions of 1-4 with Mo(CO)₆ in a refluxing alkane solvent yielded complexes of the type (L)Mo(CO)₅ (L = (Et₂N)₂PC₂F₅, 5; (Et₂N)₂PC₂F₃6; (C₄H₄N)₂PC₂F₅7 and (C₄H₈N)₂PC₂F₅8) as colorless solids in low to moderate (25-62%) yields. Complexes 5, 7 and 8 were structurally characterized by single crystal X-ray diffraction. A comparison of IR stretching frequencies and X-ray bond length data suggests these ligands approximate the electronic influence of phosphites.     

Synthesis,structure, and chemistry of a 1-thia-4-azanaphthalene

From a crystal structure determination and thermal rearrangement studies, it is evident that 1-methyl-2-carbethoxy-3-phenyl-1-thia-4-azanaphthalene is an $\text{alias}$ for a molecule more properly represented by a name emphasizing its zwitterionic character.     

Heteroatom chemistry of cyclic benzopolychalcogenides: Synthesis and characterization

Many benzopolychalcogenides, for example benzotrithioles, benzotetrathiins, and benzopentathiepins were synthesized from corresponding 1,2‐benzenedichalcogenols as starting compounds. The stability of the pentathiepin ring toward functional groups was confirmed by use of amino and sulfide groups as substituents in the molecule of benzopentathiepin. Furthermore, the intramolecular interaction between two polysulfide rings was also studied by synthesis of bisbenzotrithiole, 7,7′‐diethyl‐4,4′‐ethylenedioxybis (benzo[1,2‐d][1,2,3]trithiole). © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:419–423, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10069     

Synthesis and characterization of phosphate-modified LiMn2O4 cathode materials for Li-ion battery

<正>LiMn_2O_4 spinel cathode materials were modified with 2 wt.%Li-M-PO_4(M=Co,Ni,Mn) by polyol synthesis method.The phosphate surface-modified LiMn_2O_4 cathode materials were physically characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS).The charge-discharge test showed that the cycling and rate capacities of LiMn_2O_4 cathode materials were significantly enhanced by stabilizing the electrode surface with phosphate.     

Synthesis, characterization and coordination chemistry of a macrocyclic ligand containing arsenic donors

The preparation and characterization of the macrocyclic diamido-diarsine ligand [As2N2]Li2(1,4-dioxane) (1) (where As2N2 = PhAs(CH2SiMe2NSiMe2CH2)2AsPh) and a series of early transition metal complexes are presented. The complexes [As2N2]MCl2 (M = Zr, 2; Ti, 4) and the complex ([As2N2]Y)2(mu-Cl)2 (5) can be prepared by reaction of 1 with the corresponding THF adduct of the metal halide. The iodide derivative of 2, [As2N2]ZrI2 (3) can be prepared by reaction with iodotrimethylsilane. The lithium complex 1 displays a very long lithium-arsenic bond distance of 3.162(10) A, and the yttrium complex 5 is the first known complex containing a yttrium-arsenic bond. Reduction of 2, 3 or 4 using C8K or activated magnesium decomposed the complexes in such a manner that the ligand was separated from the metal centre. Indirect evidence suggests this may be due to reduction of arsenic in the ligand in preference to the metal.     

异羟肟酸氧钒化合物的合成表征及配位化学性质研究

分别以不同的异羟肟酸为配体，合成了3个氧钒(Ⅳ)配合物，运用元素分析、红外光谱、核磁共振谱(^1H NNR，^13C NMR，^51V NMR)、电子顺磁共振和电子吸收光谱等测试手段对配合物进行了表征．分别在不同的羟基醇中以氧钒(Ⅳ)配合物阱BHAOV为基础，合成了2个含烷氧基的五价氧钒(Ⅴ)化合物．在吡啶中合成了含吡啶的六配位氧钒(Ⅳ)配合物阱BHAOV(PY)，Ⅴ占据第6位置S原子，可使其不被氧原子进攻而氧化，要使Ⅴ内层发生氧化，在四价钒上至少有一个空的配位位点是完全必要的．而且还研究了BHAOV在乙腈中的配位反应动力学．     

Synthesis, structural characterization, and molecular modeling of dodecaniobate keggin chain materials

Four new isostructural one-dimensional dodecaniobate Keggin materials, Na12[Ti2O2][TNb12O40] x xH2O and Na10[Nb2O2][TNb12O40] x xH2O with T = (Si or Ge), have been synthesized hydrothermally using a Lindqvist-ion salt, Na7[Nb6O19H] x 15H2O, as the precursor. Their structure, consisting of chains of Keggin ions [TNb12O40]16- linked by [Ti2O2]4+ or [Nb2O2]6+ bridges, was solved ab initio from powder diffraction data. The location of the charge-balancing sodium atoms and the water molecules was further investigated by molecular simulations. These compounds were also characterized by IR and solid-state 1H, 29Si, and 23Na MAS NMR spectroscopies. The structural relationships between these and related phases based on similar Keggin ion building units are discussed.     

Synthesis,characterization, and antitumor evaluation of 4-aminoximidofurazan derivatives

Reactions of 3-amino-4-aminoximidofurazan (AAOF) with Wittig–Horner reagents, trialkylphosphites, trisdialkylaminophosphines as well as the thiating Lawesson and Japanese reagents were studied. Elemental analysis and spectroscopic measurements were in good accord with the structures postulated for the new products. The antitumor activities of certain selected new compounds were screened, in vitro, against a panel of five (liver; HepG2; breast; MCF-7; lung; A549; colon; HCT116; and prostate PC3) human solid tumor cell lines.     

Synthesis,structure, and characterization of Cu4S10(4-methylpyridine)4

The title compound, Cu₄S₁₀(4-methylpyridine)₄ · 4-methylpyridine was prepared by three different reactions: the oxidation of copper power by sulfur and the reaction of copper (I) sulfide (or CuBr-SMe₂) with cues sulfur, both in the coordinating solvent, 4-methylpyridine. Red crystals of the compound obtained by layering with hexans were subjected to single crystal X-ray diffraction. The structure was refined toR=0.026 and R _w =0.036 in a space groupP1bar (No. 2), withZ=2,a=13.983 (2) A,b=15.384( 2) Å,c=9.660 (1) Å, = 93.87 (1)°,=93.38 ==(1)°,V=2037.9 (9) ų. The commpound has approximate S₄ symmetry and consists of two pentasuffide chains linking four Cu(I) ions, each with a coordinating 2-methylpyridine. The infrared spectrum was dominated by absorption due to coodinated 4-methylpyridine with several low-energy peaks attributable to S-S stretches, which were also observed by Raman spectroscopy. A featureless electronic absorption spectrum yielded a single peak in the mar ultraviolet upon computer enhancement (=334 nm, = 10,000), most likely an intraligand transition. Cyclic voltammetry indicates that the polysulfide complex undergoes irreversible oxidation and reduction at +0.04 and –0.34 V vs. SCR respectively, at NS K in 4-methylpyridine when swept at 20 mV/sec. The electrochemical behavior was unvaried even at sweep rates as high as 100 V/sec.     

Combinatorial chemistry of materials,polymers and catalysts

The need for new materials and catalysts has never been satisfied by conventional methods. Chemical diversity is much too large to be explored systematically. Combinatorial chemistry applied to the discovery of new materials and catalysts can provide new lead structures, which has already been demonstrated by pioneers in the field. Combinatorial chemistry is much more than just a multiplication of experiments. In order to provide the results expected, combinatorial chemistry requires the combination of library preparation, characterization, identification of the desired properties and retrievable collection of the accumulated data in an intelligent data base. The state of the art of combinatorial chemistry in materials, polymer and catalysis research is reviewed. We have been engaged in the manual and automated preparation of catalyst libraries by liquid phase techniques (sol‐gel‐process and hydrothermal synthesis) for a variety of applications. The chemical nature of the components prepared on the library is not only a product of the liquid phase reaction conditions, but also of the drying and calcination process. High‐throughput characterization of the library components is therefor as important as the identification of desired materials properties. Automated micro‐X‐ray‐fluorescence spectrometry with a commercial instrument has been used successfully to identify chemical compositions of library components. Automated microdiffraction has been used to characterize the microstructure of the materials prepared. For the sensitive detection of reaction energies on catalyst libraries emissivity corrected IR‐thermography has been developed. It is used to identify catalytic activity of library components through the heat of reaction with high efficiency. This method has been applied to total oxidation, selective oxidation and hydrogenation reactions. Although much slower, but more detailed information was obtained with spatially resolved mass spectrometry. In a simple set‐up product composition of selective oxidation reactions have been scanned with the help of a simple gas analyzer (quadrupole mass spectrometer). A remarkable discrimination of product selectivity was recorded on a diverse library containing amorphous microporous mixed oxide catalysts. With high resolution MS more difficult problems, such as the differentiation of products of the same unit mass, such as CO, N₂ and ethylene can be solved in high throughput modes. The selectivities observed correlate well with the behaviour of the materials under conventional reaction conditions.     

Synthesis and characterization of nitrogen-rich azo-linked conjugated polymer materials

Efficient azo-linked polymers of 2,4,6-tris(4-nitrophenyl)pyridine-melamine (TNPP-M), and 2,4,6-tris(4-nitrophenyl)pyridine-sulfanilamide (TNPP-S) were prepared by condensation polymerization technique from TNPP-based monomer reacting with amines as melamine and sulfanilamide. The synthesized polymer structure was confirmed by various experimental techniques, such as Fourier transform infrared spectroscopy, solid-state ¹³C NMR, and X-ray diffraction (XRD). Particle size was calculated using Williamson–Hall (W–H) plot from powder XRD pattern. The thermal analysis and scanning electron microscopy of TNPP-S polymer displayed an excellent thermal stability and capsule-like morphology was observed. UV/visible absorptions of TNPP-S and TNPP-M polymers exhibit two bands, a strong band at 365?nm, and a shoulder at 385?nm for TNPP-M; these polymeric semiconducting materials could be useful for solar fuel cell applications.     

Synthesis,characterization and potential applications of new materials in the mesoporous range

M41S is the designation of a new type of mesoporous structures. The characteristics of these materials are large surface areas and very narrow pore size distributions, with pore diameters tunable from 15 to 100 Å. The M41S family consists of MCM-48, which has a cubic ordered pore structure, MCM-41, which has a hexagonally ordered pore structure and MCM-50, which has an unstable lamellar structure. In this review we cover the synthesis, modification, characterization and potential applications of these materials.     

Synthesis and characterization of copper 4-carboxyphenylphosphonates

Three new copper 4-carboxyphenylphosphonates with formulae Cu(HOOCC₆H₄PO₃)·2H₂O, Cu(HOOCC₆H₄PO₃) and Cu₃(OOCC₆H₄PO₃)₂·3H₂O were prepared and characterized by thermogravimetric analysis, X-ray diffraction analysis, energy-dispersive X-ray microanalysis and infrared spectroscopy. The preparation conditions of Cu(HOOCC₆H₄PO₃)·2H₂O and Cu₃(OOCC₆H₄PO₃)₂·3H₂O differ in the acidity of the reaction mixture, where Cu(HOOCC₆H₄PO₃) was prepared under hydrothermal conditions. Copper 4-carboxyphenylphosphonate with formula Cu₃(OOCC₆H₄PO₃)₂·3H₂O reacts with 4-carboxyphenylphosphonic acid to form Cu(HOOCC₆H₄PO₃)·2H₂O.Cu(HOOCC₆H₄PO₃)·2H₂O is orthorhombic, space group Pbcn (no. 60), a=8.234(2) Å, b=9.438(2) Å, c=24.899(5) Å. Cu(HOOCC₆H₄PO₃) crystallizes in the monoclinic space group P2₁/c (no. 14), a=19.0951(3), b=8.0968(4), c=5.2111(11) Å, β=94.914(6)°, Z=4. Its layered structure is composed of distorted CuO₆ octahedra arranged hexagonally in a gibbsite-like manner around two phosphonate groups, which have their carboxyphenyl groups extending into the space above and below the copper–phosphonate layer. Infrared spectra indicate that for both Cu(HOOCC₆H₄PO₃)·2H₂O and Cu(HOOCC₆H₄PO₃) the acid hydrogen is present at the carboxyl group and not at the phosphonic group.     

Toward efficient functionalization of polystyrene backbone through ketene chemistry: Synthesis,characterization, and DFT study

In this study, polystyrene was functionalized with Meldrum's acid toward the introduction of the ketenes (CCO) system to its backbone for producing a dramatically reactive intermediate. Meldrum's acid, as a ketene source, was reacted by poly(styrene-co-p-chloromethyl styrene) through a simple nucleophilic reaction to synthesize poly(styrene-co-styryl Meldrum's acid). Then, the pendant Meldrum's acid under thermal treatment converted to ketene intermediate resulting in highly reactive polystyrenes derivatives, which rapidly reacted by nucleophilic reagents to afford ultimate organic building blocks. The polystyrene derivatives were characterized using elemental analysis, FT-IR, high-resolution solid-state NMR, thermogravimetric analysis (TGA), and differential thermogravimetric analysis (DTG). To clarify the evolutionary mechanisms of polystyrene products, density functional theory (DFT) method B3LYP with the 6–311++G(2d,p) basis set was used. We studied the preparation of polystyrene model compounds through Meldrum's acid thermolysis and nucleophilic substitution. The kinetic and thermodynamic parameters in all reactions and the structural and electronic properties of all molecules were calculated. These data exhibited that based on Gibbs Free energy values, the structure of syndiotactic polystyrene is more stable than that of isotactic polystyrene. Furthermore, it was found that the presence of an electron donor or acceptor substituent on the polystyrene structure affects the electronic bandgap.