Reaction Of Tetrakis Research Articles

Use of Tetrakis(2-ethoxyethoxy)silane for the Preparation of Ethylalkoxysilanes of a Single Structure by the Organomagnesium Methods

A new method for obtaining individual ethylalkoxysilanes of various types of substitution without using chlorosilanes is proposed based on the reactions of tetrakis(2-ethoxyethoxy)silane with the Grignard reagents. The structures of the compounds obtained are confirmed by NMR spectroscopy and GLC.

Synthesis and characterization of flame‐retardant polyurethane based on new chain extenders

AbstractA series of novel flame‐retardant waterborne polyurethanes (FWPU) were synthesized with tris(hydroxymethyl)phosphine (THPO) obtained from the reaction of tetrakis(hydroxymethyl)phosphonium sulfate and bis(2‐hydroxyethyl)terephthalate from the alcoholysis of waste poly(ethylene terephthalate) as flame‐retardant chain extenders. Influences of THPO on flame retardancy and bonding properties of FWPU were investigated using limiting oxygen index (LOI) measurement, vertical burning test, cone calorimeter test (CCT), thermogravimetric analysis and shear tensile test. The results of LOI, vertical burning test and CCT indicated that flame retardancy of FWPU was improved with the introduction of THPO. The peak of heat release rate of FWPU with 1.5 wt% THPO was 401 kW m−2. After hard segment flame‐retardant modification, the initial bonding strength of FWPU adhesive increased by 150%, and the final bonding strength decreased slightly. A new way is provided for the design of novel reactive FWPU which maintained better flame retardancy and adhesive properties after hard segment flame‐retardant modification. © 2022 Society of Industrial Chemistry.

Unexpected formation of poly-functionalized fulvenes by the reaction of a tetraaryl[5]cumulene with iodine.

Longer cumulenes have come to draw considerable attention due to their unique properties and reactivities, leading to various hydrocarbons. In this manuscript, we describe the reaction of tetrakis(p-methoxyphenyl)[5]cumulene with iodine to afford poly-functionalized fulvenes via unexpected migration of a terminal aryl ring under ambient conditions. The obtained iodinated fulvenes were utilized in Suzuki-Miyaura cross-coupling reactions affording penta- and fully-arylated fulvenes successfully.

Oxide-Supported Titanium Catalysts: Structure–Activity Relationship in Heterogeneous Catalysis, with the Choice of Support as a Key Step

The reactions of tetrakis(neopentyl)titanium, TiNp4 (1), with the surface of three solid oxides, silica, silica–alumina, and alumina, all partially dehydroxylated at 500 °C under vacuum were achieved. The resulting supported organometallic species react with dihydrogen to form the corresponding supported hydrides. The preparation of supported titanium hydrides on alumina is described here in detail, and the species obtained were extensively characterized by FTIR, solid-state NMR and EPR spectroscopy, and mass-balance analysis. The supported titanium hydride species were tested in three important reactions for petrochemistry: epoxidation of 1-octene, depolymerization of Fischer–Tropsch waxes, and polymerization of ethylene. The activities of titanium hydrides supported on alumina were compared to those of their silica- and silica–alumina-supported analogues.

Solvothermal Synthesis of Spherical Zirconia Particles Having Meso-Macro Bimodal Pore Structures

By the thermal reaction of tetrakis(acetylacetonato)zirconium in 1,4-butanediol at 300 °C for 2 h, spherical zirconia particles with large surface areas and large pore volumes both in the meso and ...

A Copper(II) tris-imidazolylphosphine complex as a functional model of flavonol 2,4-dioxygenase

Reaction of tetrakis(acetonitrile)copper(I) perchlorate ([Cu(NCCH3)4][ClO4]), tris-1-ethyl-4-methylimidazolylphosphine (T1Et4MeIP) (1) and 3-hydroxyflavone (flavH) under ambient conditions produces an in-situ generated flavonol bound copper(II) complex, which converts to a stable green complex that formulates to [Cu(T1Et4MeIP)(flav)][ClO4] (2). The crystal structure of 2 was determined by X-ray diffraction and crystallizes in a triclinic system (P1¯) with unit cell dimensions of a = 14.537(15) Å, b = 15.794(14) Å, c = 17.044(17) Å, α = 65.58(3)˚, β = 86.80(5)˚, γ = 73.34(4)˚, V = 3376(6) Å3 and Z = 2. While the five-coordinate copper(II) complex is stable under ambient conditions in the solid state, it undergoes oxidative scission of the flavonol pyrone ring under photolytic (300 nm) and/or thermal (120 °C) conditions in the presence of molecular oxygen. The degradative process produces the corresponding methylated products: methylbenzoate, methyl salicylate and N,N-dimethylbenzamide. In addition, the previously undisclosed single crystal X-ray structure of tris-1-ethyl-4-methylimidazolylphosphine (1), T1Et4MeIP, is also reported.

Urea-based porous organic polymer/graphene oxide hybrid as a new sorbent for highly efficient extraction of bovine serum albumin prior to its spectrophotometric determination

A 3D urea-based porous organic polymer (Urea-POP) was prepared via the reaction of tetrakis(4-aminophenyl)methane and 1,4-Phenylene diisocyanate. The polymer was subsequently reacted with 2D layered nanosheets of graphene oxide (GO) to prepare Urea-POP/GO as a novel and highly efficient sorbent for pre-concentration and extraction of serum albumin samples, prior to spectrophotometric determination. The hybrid material combines advantages of both POP and GO such as hydrophilicity, high dispersion stability, porosity, and having a large number of nitrogen- and oxygen-containing functional groups. Parameters which influence the extraction efficiency such as the amount of the adsorbent, pH of sample solution, ionic strength, adsorption and desorption time were investigated and optimized. For the method, detection limit of 0.068 mg L−1 and determination coefficient (R2) of 0.9991 were obtained. The intra- and inter-day was calculated with five replicates in the same day and seven consecutive days, respectively. Intra-day and inter-day precisions were 1.7% and 5.9%, respectively. The maximum sorption capacity was 357.1 mg g−1, which is higher than the other reported sorbents. The proposed method was demonstrated to be sensitive enough for determination of serum albumin from bio-samples.

Novel nanostructured smart, photodynamic hydrogels based on poly(N-isopropylacrylamide) bearing porphyrin units in their crosslink chains: A potential sensitizer system in cancer therapy

Novel nanostructure, pH-thermo dual responsive photodynamic hydrogels based on poly(N-isopropylacrylamide) were successfully synthesized by in situ dispersion polymerization of NIPAAm with 5,10, 15, 20-tetrakis(4-N-carbonylacrylic aminophenyl)porphyrin (2% and 4% w/w) in the presence of methylene-bis-acrylamide (MBA) in water. 5, 10, 15, 20-tetrakis (4-N-carbonylacrylic aminophenyl)porphyrin (CAA-TPP) was designed and synthesized for the first time via reaction of tetrakis(4-aminophenyl)porphyrin (NH2-TPP) with maleic anhydrid and was applied as a crosslinker. The structure of the 5, 10, 15, 20-tetrakis(4-N-carbonylacrylic aminophenyl) porphyrin and hydrogels was thoroughly studied by a variety of techniques such as NMR, FT-IR and UV–visible spectrophotometer. The surface morphology of freeze-dried hydrogels using SEM showed one-dimensional nanostructured with uniform morphology of self-assembled interconnected nanofibers. Rheological measurement results were showed that the incorporation of porphyrin onto polymer structure can provide hydrogels without the loss of thermoresponsive viscoelastic properties. The lower critical solution temperatures (LCST) of P[NIPAAm-co-CAA-TPP] hydrogels in water were measured by the cloud point (CP) method. The LCST of P[NIPAAm-co-CAA-TPP (2%)] and P[NIPAAm-co-CAA-TPP (4%)] were at about 40 °C and 43 °C, respectively. The results showed that an increase in porphyrin content makes the LCSTs of the hydrogels increase. Swelling measurements of hydrogels indicated sensitivity to temperature and pH, suggesting that the P[NIPAAm-co-CAA-TPP]s were temperature/pH dual stimulus-responsive hydrogels. In this work, the efficiency of P[NIPAAm-co-CAA-TPP (2%)] and P[NIPAAm-co-CAA-TPP (4%)] as photodynamic therapy (PDT) systems were investigated. The production of reactive singlet oxygen, cytotoxity and phototoxicity of them were assessed. The study showed that the singlet oxygen production ability of P[NIPAAm-co-CAA-TPP (2%)] can be well controlled by irradiation time compared with free porphyrin. We tested these two hydrogels on A453 cells to compare their effectiveness. P[NIPAAm-co-CAA-TPP (2%)] and P[NIPAAm-co-CAA-TPP (4%)] exhibited cell viability over 97% and good photocytotoxity, indicating they are promising photodynamic systems for cancer therapy.

Synthesis of 1-substituted 2,6,7-trioxa-4-phospha-1-borabicyclo[2.2.2]octan-1-uide

ABSTRACT1-Substituted 2,6,7-trioxa-4-phospha-1-borabicyclo[2.2.2]octan-1-uides were obtained in 31–71% yields by the reaction of tetrakis(hydroxymethyl)phosphonium sulfate with alkyl- or arylboronic acids in the presence of tetrabutylammonium hydroxide.

Synthesis and characterization of green-to-yellow emissive Ir(III) complexes of pyridylbenzothiadiazine ligand

Reaction of tetrakis(2-phenylpyridinato-C2,N′)(μ-dichloro)di-iridium with 3-(pyridin-2-yl)-4H-benzo[e][1,2,4]thiadiazine (L1) under neutral and basic media afforded the charged and neutral Ir-complexes, 1 and 2, respectively, in good yields (63–79%). Single-crystal XRD analysis confirms that the ancillary ligands in both 1 and 2 bind to the iridium via coordination of N2 of the benzo[e][1,2,4]thiadiazine. Upon isolation of the neutral complex, the sulfur rapidly oxidizes to form 2. The UV–vis absorption spectra of the complexes exhibit both ligand-centered and mixed metal-to-ligand and ligand-to-ligand charge transfer transitions that are typical of many heteroleptic iridium complexes. Complexes 1 and 2 were emissive at room temperature in the green and yellow region of the electromagnetic spectrum, respectively, albeit with poor photoluminescence quantum yield (ΦPL = 1.1–2.5%).

At the edge between metal organic chemical vapor deposition and atomic layer deposition: Fast Atomic Sequential Technique, for high throughput conformal deposition

A comparison of the metal organic chemical vapor deposition (MOCVD), atomic layer deposition (ALD), and a new deposition method, the Fast Atomic Sequential Technique (FAST®), was completed. Within all the materials which can be deposited by the FAST technique, the case study of TiN thin film deposition by reaction of tetrakis(diethylamino)titanium precursor with NH3 reactant gas is presented here. The thickness and resistivity measurements revealed that while the FAST deposition is five times faster than the ALD, the lowest resistivity achieved is four times lower than MOCVD minimum resistivity, thus equivalent to ALD at 100 μΩ cm. Moreover, a 25% gain toward lower action energy of the FAST deposition compared to the MOCVD tends to support a different reaction mechanism between the two techniques. Additionally, the FAST technique introduces new process parameters offering the possibility to change the deposition technique to either a MOCVD-like or to an ALD-like deposition in the same tool, thus allowing to choose between high throughput and high conformality or for a compromise of the two. Then, using high aspect ratio vias, the higher conformality of FAST compared to MOCVD is shown. Evolution of the conformality on different aspect ratios devices shows that while ALD is conformal whatever the aspect ratio, MOCVD is not suitable for vias with an aspect ratio higher than 5:1, whereas FAST can achieve a conformality higher than 60% in aspect ratios of 35:1.

Imidazolin-2-iminato Ligand-Supported Titanium Complexes as Catalysts for the Synthesis of Urea Derivatives.

The reactions of tetrakis(dimethylamido)titanium(IV) [Ti(NMe2)4] with three different imidazolin-2-imines (Im(R)NH; R = tert-butyl (tBu), mesityl (Mes), and 2,6-diisopropylphenyl (Dipp)) afforded the corresponding titanium imidazolin-2-iminato complexes [(Im(R)N)Ti(NMe2)3] (R = tBu, 1a; R = Mes, 1b; R = Dipp, 1c). Treatment of complex 1a with two different carbodiimides [R'N═C═NR'; R' = cyclohexyl (Cy) and isopropyl (iPr)] resulted in the formation of imidazolin-2-iminato titanium mono(guanidinate) complex of the type [(Im(R)N)Ti(R'NC(NMe2)NR') (NMe2)2 (R' = iPr; R = tBu (2a), R = Dipp (2c); R' = Cy, R = tBu (3a)], as yellow solid in 94% yield. However, a similar reaction of 1b and 1c with 2 equiv of phenyl isocyanates at ambient temperature resulted in the formation of corresponding titanium bis(ureate) complexes [(Im(R)N)Ti{κ(2)-OC(NMe2)NPh}2(NMe2)] (R = Mes, 4b and R = Dipp, 4c). Three equivalents of phenyl isothiocyanate reacted with complex 1c to afford respective titanium tris(thioureate) complex [(Im(Dipp)N)Ti{κ(2)-SC(NMe2)NPh}2{κ(1)-SC(NMe2)NPh}] (6c). The molecular structures of 1a-c, 2a, 2c, 3a, 4c, and 6c were established by X-ray diffraction analyses, and, from the solid-state structures of 1a-c, 2a, 2c, 3a, 4c, and 6c, it was confirmed that the imidazolin-2-iminato titanium bond in each case is very short and possesses a multiple-bonding character. The imidazolin-2-iminato titanium complex 1c was utilized as a precatalyst for the addition of amine N-H bond to phenyl isocyanate. High yields of the corresponding urea derivatives were achieved under mild conditions. The mechanistic study of the aforementioned catalytic reaction was performed, and the active catalyst complex 7b was isolated using 2 equiv of iminopyrrole [2-(2,6-iPr2C6H3N═CH)C4H3NH] and the complex 4b. The molecular structure of 7b was thereafter established.

Hydroamination of carbodiimides, isocyanates, and isothiocyanates by a bis(phosphinoselenoic amide) supported titanium(iv) complex.

The hydroamination of heterocumulenes such as carbodiimides, isocyanates, and isothiocyanates by a bis(phosphinoselenoic amide) supported titanium(iv) complex as a precatalyst is reported here. The titanium(iv) complex [{Ph2P(Se)NCH2CH2NPPh2(Se)}Ti(NMe2)2] (1) was synthesised by the reaction of tetrakis-(dimethylamido)titanium(iv) [Ti(NMe2)4] with [{Ph2P(Se)NHCH2CH2NHPPh2(Se)}] in toluene at ambient temperature. Titanium complex 1 proved to be a competent pre-catalyst for the addition of an amine N-H bond to carbodiimides, isocyanates, and isothiocyanates. The reaction scope was expanded to reactions of aliphatic and aromatic amines with phenylisocyanates and phenylisothiocyanates in toluene solvents proceeding rapidly at room temperature with 5 mol% catalyst loadings to yield the corresponding urea and thio-urea derivatives up to 99%. However, ambient temperature was needed for hydroamination of 1,3-dicyclohexylcarbodiimide. The amine addition reactions with isocyanates showed first order kinetics with respect to catalyst 1 as well as substrates. The most plausible mechanism for the hydroamination reaction was established by isolating 1,1-dimethylphenyl urea as a side product.

The first montmorillonite-supported surface single-structure titanium complex: synthesis, characterization and catalytic activity in alkene epoxidation

A well-defined single-site titanium-modified montmorillonite (MMT) with only one geometric construction ((SiO)3–Ti–NMe2) was obtained in moderate conditions. Reaction of tetrakis(dimethylamido)titanium with hydroxylated MMT was conducted by surface organometallic chemistry technique, and the surface structure was characterized by in situ Fourier transform infrared spectroscopy, 13C cross polarization magic angle spinning nuclear magnetic resonance, X-ray photoelectron spectroscopy, extended X-ray absorption fine structure, and elemental analysis. The catalytic activity in alkene epoxidation was evaluated, and the results revealed that the steric hindrance of the substances is responsible for the catalytic activity of the MMT-supported titanium complex but to the characteristic restricted layer-like structure of the MMT. Copyright © 2014 John Wiley & Sons, Ltd.

Porous titanium and zirconium oxo carboxylates at the interface between sol–gel and metal–organic framework structures

Reaction of Ti(OiPr)4 with several tri- and tetracarboxylic acids, followed by hydrolysis, resulted in microporous, structured materials, with microporous surface areas up to 340 m(2) g(-1). Depending on the kind of carboxylic acid, the Ti : COOH ratio and the Ti : H2O ratio, either pillared layered or surface fractal 3D structures were obtained according to SAXS measurements. The most pronounced layered structure was found for 1,2,4,5-benzenetetrabenzoic acid and a Ti : H2O ratio of 4, while a Ti : H2O ratio of 2 resulted in a 3D structure. The use of 1,3,5-benzenetricarboxylic acid or 1,3,5-benzenetribenzoic acid resulted in similar structures which, however, were less pronounced and less ordered. The reaction of tetrakis(4-carboxyphenyl)silicon with Ti(OiPr)4 or benzenetribenzoic acid with Zr(OiPr)4 gave 3D structures for all Ti : H2O ratios.

A Conformationally Flexible Dinuclear PtIIComplex with Differential Behavior of its Two States toward Quadruplex DNA

The reaction of tetrakis(pyridine-2-yl)pyrazine (tppz) with 2 equiv of (2,2'-bpy)Pt(II) in water yields two isomeric dinuclear cations, [{Pt(2,2'-bpy)}2 (tppz)](4+) , in which Pt coordination exclusively takes place through the two pairs of pyridine-2-yl nitrogen atoms. The two conformational isomers differ in their overall shape, with the formation of "Z" and "U" shapes, which are formed at 40 °C (Z isomer, 1) and under reflux conditions (U isomer, 2), respectively. X-ray crystal-structure analyses of the Z isomer, [{Pt(2,2'-bpy)}2 (tppz)](PF6 )4 ⋅3 CHCl3 ⋅4 H2 O (1 a), and of the U isomer, [{Pt(2,2'-bpy)}2 ](PF6 )4 ⋅2 CH3 CN⋅1.5 H2 O (2 a), were carried out. Co-crystallization of compound 2 with PtCl2 (2,2'-bpy) yielded [{Pt(2,2'-bpy)}2 (tppz)](BF4 )4 ⋅[PtCl2 (2,2'-bpy)]⋅4.5 H2 O (3), in which the PtCl2 (2,2'-bpy) entity was sandwiched between the two 2,2'-bpy faces of the U-shaped cation (2). Quantum chemical calculations revealed that the U isomer was more stable than the Z isomer, both in the gas phase and in an aqueous environment. These two isomers display different affinities toward duplex DNA and human telomeric quadruplex DNA (Htelo), as concluded from CD spectroscopy and FID assays. Thus, the U isomer binds significantly more strongly to quadruplex DNA (DC50 =0.38 μM) than the Z isomer (DC50 =8.50 μM).

Preliminary studies on the role and reactions of tetrakis(hydroxymethyl)phosphonium chloride in polyacrylamide gel dosimeters

A major source of dosimetric inaccuracy in normoxic polymer gel dosimeters is local variations in the concentration of oxygen scavenger. Currently, a phosphorus compound, tetrakis(hydroxymethyl)phosphonium chloride (THPC), is the oxygen scavenger of choice in most polymer gel dosimetry studies. Reactions of THPC in a gel dosimeter are not limited to oxygen. It can possibly be consumed in reacting with gelling agent, water free-radicals and polymer radicals before, during and after irradiation, hence affecting the dose response of the dosimeter in several ways. These reactions are not fully known or understood. It is our hypothesis that THPC not only scavenges radical species but also modifies the morphology of the gelatin network and of the polymer, possibly by intervening in the polymerization of monomers. These hypotheses are investigated in an anoxic acrylamide-based gel dosimeter. Scanning electron microscopy results indicate gelatin pores decreasing from 70 to 40 µm and a very different radiation-induced polymer structure in samples containing THPC; Fourier-transform Raman spectroscopy shows a two-fold reduction in the dose constants of monomer consumption; however, a significant change in the relative dose constants of monomer consumption as a function of dose could not be detected.

Facile synthesis of rhodium and iridium complexes bearing a [PEP]-type ligand (E = Ge or Sn) via E–C bond cleavage

Rhodium and iridium complexes bearing a tridentate [PEP] type ligand ([PEP] = {o-(Ph(2)P)C(6)H(4)}(2)E(Me); E = Ge or Sn) were synthesized through the phosphine exchange reaction accompanied by selective E-C bond cleavage. The ligand precursors {o-(Ph(2)P)C(6)H(4)}(2)EMe(2) (E = Ge or Sn) were readily obtained in excellent yields by treating {o-(Ph(2)P)C(6)H(4)}(2)Li with 0.5 equivalents of Me(2)ECl(2). Tris(triphenylphosphine)rhodium(I) carbonyl hydride M(H)(CO)(PPh(3))(3) (M = Rh, Ir) cleaved one of the E-Me bonds of {o-(Ph(2)P)C(6)H(4)}(2)EMe(2) exclusively to afford the trigonal bipyramidal (TBP) complexes, [PEP]M(CO)(PPh(3)). Square-planar rhodium complexes [PEP]Rh(PPh(3)) were also prepared from the reactions of tetrakis(triphenylphosphine)rhodium(I) hydride Rh(H)(PPh(3))(4) with {o-(Ph(2)P)C(6)H(4)}(2)EMe(2). Further, the trans influence of group 14 elements E (E = Si, Ge, Sn) in [PEP]Rh(PPh(3)) is discussed in terms of the (1)J(Rh-P) coupling constants, indicating that E exhibited a stronger trans labilizing effect in the order Sn < Ge < Si.

Synthesis and Structural Characterization of 1,2,4-Diazaphospholide Complexes of Titanium(IV) and Titanium(III)

Two 1,2,4-diazaphospholide complexes of [Ti(η(2)-3,5-Ph(2)dp)(4)] and paramagnetic [Ti(η(2)-3,5-tBu(2)dp)(3)] were prepared by the reaction of tetrakis(dimethylamido)titanium(IV) with 3,5-diphenyl-1,2,4-diazaphophole, H[3,5-Ph(2)dp], or by the treatment of 3,5-tert-butyl-1,2,4-diazaphopholide potassium, K[3,5-tBu(2)dp], with titanium trichloride. Complexes can be viewed as the core of P(σ(2)λ(3))-functionalized metallodendrimers, in which the metal atoms are exclusively η(2)(N,N) bonding to the 1,2,4-diazaphospholides while P atoms (σ(2)λ(3)) with electron lone pairs are located on the periphery of the molecules.

Synthesis and structure of peri‐substituted boron/pnictogen naphthalene derivatives

AbstractThe reaction of tetrakis(thf)lithium dimesityl‐1,8‐naphthalenediylborate with either Ph2 SbCl or Ph2BiCl afforded 1‐(diphenylantimony)‐8‐(dimesitylboron)naphthalenediyl (1) and 1‐(diphenylbismuth)‐8‐(dimesitylboron) naphthalenediyl (2). These unprecedented boron/antimony and boron/bismuth derivatives have been characterized by multinuclear NMR spectroscopy, elemental analysis, and X‐ray single‐crystal analysis. The latter reveals that the 1,8‐naphthalenediyl backbone enforces short E→B (E = Sb, Bi) distances of 3.216 Å for 1 and 3.330 Å for 2. Natural bond order studies indicate that these short contacts are associated to lp(E)→p(B) interactions, which contribute to the stability of the compounds by 8.65 kcal/mol−1 in the case of 1 and 6.32 kcal/mol−1 in the case of 2. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:500–505, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20713