New fluorine-containing titanium bis(salicylideneimino) complexes in olefin polymerization

The titanium salicylideneimino complex TiCl₂{²-1-[NR=C(H)]-2-O-3,5-Bu^t ₂-C₆H₂}₂ (R = 2,3,5,6-F₄C₆H) was synthesized. In the presence of polymethylaluminoxane, the complex efficiently catalyzes polymerization of ethylene and, to a lesser degree, atactic propylene. The resulting polymers are characterized by high melting points, molecular weights, and polydispersity indices, as well as elastomeric (polypropylene) properties.     

New dinuclear fluorine-containing bis(salicylidene)imine titanium complex: synthesis and catalytic properties in polymerization of ethylene and propylene

New dinuclear titanium(IV) dichloride complex with the chelating bis-4,4-bis-imine-(3,5-di-tert-butylsalicylidene)octafluorobiphenyl ligand was synthesized. In the presence of polymethylaluminoxane (MAO), the complex showed high catalytic activity in ethylene polymerization leading to high molecular (M _n 2500000) linear polyethylene with a high polydispersity index (M _w/M _n 7.0) and high melting point (142 °C). The catalytic activity in propylene polymerization in a medium of liquid monomer is substantially lower, and the polypropylene formed is a high molecular atactic elastomer.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2652–2656, December, 2004.     

Modification of titanium catalytic systems for 1,4-cis-polyisoprene synthesis

The kinetics of isoprene polymerization in an aliphatic solvent on a titanium catalyst modified with n- and π-electron-donor additives, with preliminary single circulation of the reaction mixture through a tubular turbulent apparatus, was studied.     

Synthesis and structures of (R)-cyclopentadienyl-binaphthoxy titanium(IV) complexes and catalytic properties for olefin polymerization

Two new chiral pre-ligands, (R)-3,3'-bis(tetramethylcyclopentadienyl)-2,2'-bismethoxy-1,1'-bisnaphthalene (1) and (R)-3-tetramethylcyclopentadienyl-2,2'-bismethoxy-1,1'-bisnaphthalene (2), were synthesized by reaction of (R)-3,3'-dilithium-2,2'-bismethoxy-1,1'-bisnaphthalene with 2,3,4,5-tetramethyl-2-cyclopentenone at room temperature. Treatment of the pre-ligands 1 and 2 with butyllithium and Me(3)SiCl first, and subsequently with TiCl(4) (2 and 1 equiv for 1 and 2, respectively) afforded a binuclear complex (R)-3,3'-bis[(tetramethylcyclopentadienyl)trichlorotitanium]-2,2'-bismethoxy-1,1'-bisnaphthalene (3) and a mononuclear complex (R)-3-(tetramethylcyclopentadienyl)trichlorotitanium-2,2'-bismethoxy-1,1'-bisnaphthalene (4) in moderate yields. Complexes 3 and 4 were further converted into constrained geometry complexes (R)-1,1'-bis{2,2'-naphthoxy-3,3'-bis[(tetramethylcyclopentadienyl)dibromotitanium]} (5) and (R)-1-(2-naphthoxy)-1'-(2'-naphthol)-3-(tetramethylcyclopentadienyl)dibromotitanium (6) by treatment with BBr(3). The pre-ligands 1 and 2 were characterized by (1)H and (13)C NMR and high resolution mass spectroscopy (HRMS), and the new titanium complexes 3-6 were characterized by (1)H and (13)C NMR and elemental analyses. Molecular structures of 4, 5, and 6 were determined by single-crystal X-ray diffraction analysis. Complexes 4, 5, and 6 all have a pseudo-octahedral coordination environment and adopt a three-legged piano stool geometry around the titanium atom in their solid state structures. When activated with Al(i)Bu(3) and Ph(3)CB(C(6)F(5))(4), the chiral complexes 5 and 6 show moderate catalytic activities for propylene, 1-hexene, and 5-ethylidene-2-norbornene (ENB) polymerization and ethylene/1-hexene copolymerization. The polymers produced by the chiral 5/(i)Bu(3)Al/Ph(3)CB(C(6)F(5))(4) catalyst system from the 1-hexene, and ENB polymerization and ethylene/1-hexene copolymerization with high comonomer contents exhibit optical activity.     

The catalytic activity of alkali metal alkoxides and titanium alkoxides in the hydrosilylation of unfunctionalized olefins

The catalytic activities of titanium alkoxides and alkali metal alkoxides for hydrosilylation of unfunctionalized olefins have been studied. Titanium(IV) alkoxides showed excellent catalytic activity, while alkali metal alkoxides have low catalytic activity for the hydrosilylation of olefins. However, by using titanocene dichloride as an additive, alkali metal alkoxides showed also excellent catalytic property for hydrosilylation. In comparison with titanium alkoxides, no α-adduct was obtained by using alkali metal alkoxides/Cp₂TiCl₂ as catalysts.     

On the fracture of composites based on ultrahigh-molecular-weight polyethylene and fine aluminum particles

Mechanical characteristics of polymerization filled composite materials based on ultrahigh-molecular-weight polyethylene and fine aluminum particles are studied. The prepared composites preserve their ability for high plastic deformations even when the volume filler content is φ = 0.57. For the tensile drawing of the composite material with randomly distributed particles, an equation describing the dependence of breaking stress on the volume filler content is derived. For the model of the composite with regularly ordered particles, the Nielsen equation is the approximation of the equation proposed in this work for a material with randomly distributed particles.     

Highly active three-component catalytic systems based on dialkylzirconocenes, triisobutylaluminum, and perfluorophenyl borates for synthesis of low-molecular-weight polyethylene

The catalytic properties of the zirconium complex with “constrained geometry” Me₂SiCp^*NBu¹ZrX₂ (Cp^*=C₅Me₄, X=Cl (1a), Me (1b)) and bridged bis(cyclopentadienyl)zirconocene Me₂SiCp₂ZrX₂ (X=Cl (2a), Me (2b)) during their activation with triisobutylaluminum/perfluorophenyl borates (TIBA/LB(C₆F₅)₄, L=CPh₃ (3), Me₂HNPh (4)) in ethylene polymerization under a monomer pressure of 2–20 atm were studied by comparison. Both dichloride complexes exhibit moderate activity under the action of the combined TIBA/3 activating agent and give linear high-molecular-weight polyethylene (PE). The interaction of the dimethyl complexes with TIBA/3(4) afford active sites in which the growing polymeric chain is intensely transferred to the monomer, due to which low-molecular-weight PE is formed. The dichloride complexes affected by TIBA/4 also afford low-molecular-weight PE. Analysis of the structure of the polymeric products (¹H NMR spectrometry, IR spectroscopy), molecular-weight parameters of the PE samples (gel permeation chromatography (GPC)), and kinetics of polymerization suggested that the active site contains AlBuⁱ ₃ as a heteronuclear bridged cationic complex. The influence of various basic substrates (the products of chain transfer with the terminal vinyl groups, the dimethylaniline fragment of borate4 or other amine specially introduced into the reaction mixture) on the catalytic properties of the Zr−Al site was revealed. The polymerization rate and molecular-weight parameters of PE as functions of the reaction temperature, ethylene pressure, and modifying additives were studied. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1189–1198, July, 2000.     

New anilinotropone-based titanium complexes: synthesis, characterization and application as catalysts for olefin polymerization

New titanium(IV) dichloride complexes containing 2-anilinotropone ligands have been synthesized and characterized. Bis(ligand)titanium dichloride complexes 1 and 2 were synthesized from reaction of TiCl4(THF)2 with 2 equivalents of the corresponding sodium salts of 2-(2,6-diisopropylanilino)tropone (L1) and 2-(2,3,4,5,6-pentafluoroanilino)tropone (L2), respectively. The mixed cyclopentadienyl-anilinotropone compound 3 was synthesized by reaction of the lithium salt of with CpTiCl3. The Cp-mixed micro-O bimetallic complex 4 was also isolated as a by-product owing to the adventitious presence of moisture. The molecular structures 1-4 of have been determined by single-crystal X-ray diffraction studies. Complexes 1 and 2 are isostructural and exhibit a C2-symmetric octahedral geometry, with a trans(N,N), cis(O,O) arrangement in complex 1, but with a trans(O,O), cis(N,N) arrangement in complex 2. The Cp-mixed complex 3 has a distorted square-pyramidal structure with the Cp ligand in the apical position. Bimetallic complex 4 shows a similar coordination geometry for the five-coordinate titanium atom and a pseudo-tetrahedral coordination for the second metallic centre. All new complexes, when activated with methylaluminoxane, are active in the polymerization of ethylene and propene.     

Specific features of ethylene polymerization on self-immobilizing catalytic systems based on titanium bis(phenoxy imine) complexes

The kinetics of ethylene polymerization on six methylalumoxane-activated self-immobilizing bis(phenoxy imine) complexes of titanium chloride with allyloxy groups in the m- and p-positions of the N-phenyl ring and with various substituents in the salicylaldehyde fragment was studied. The activity of the complexes in the temperature range 20–60°C and ethylene pressure of 0.4 MPa was evaluated.     

Design of postmetallocene catalytic systems of arylimine type for olefin polymerization: XIV. Synthesis of (N-Allyloxyaryl)salicylaldimine ligands and their complexes with titanium(IV) dichloride

By reaction of salicylaldehydes with bulky substituents in the positions 3 and 5 with o-, m-, and p-allyloxyaniline hydrochlorides in the presence of triethylamine a series of the corresponding (N-aryl)-salicylaldimines was obtained, which with TiCl₂(OPr-i)₂ afforded complexes of titanium(IV) dichloride L₂TiCl₂.     

New Ru3(CO)12 derivatives with bulky diphosphine ligands: synthesis,structure and catalytic potential for olefin hydroformylation

The diphosphine clusters Ru₃(CO)₁₀(dcpm) (1) and Ru₃(CO)₁₀(F-dppe) (2) as well as the bis(diphosphine) clusters Ru₃(CO)₈(dcpm)₂ (3) and Ru₃(CO)₈(F-dppe)₂ (4) have been synthesised from Ru₃(CO)₁₂ and the bulky diphosphines 1,2-bis[bis(pentafluorophenyl)phosphino]ethane (F-dppe) and bis(dicyclohexylphosphino)methane (dcpm). While the single-crystal X-ray structure analyses of 1, 2 and 3 show the expected μ₂-η² coordination of the diphosphine ligands, that of 4 reveals an unusual structure with one μ₂-η²-diphosphine and one μ₁-η²-diphosphine ligand. The clusters 1–4 catalyse the hydroformylation of ethylene and propylene to give the corresponding aldehydes, 2 showing higher activities than those observed for Ru₃(CO)₁₂ and Ru₃(CO)₁₀(dppe).     

Structural researches on organotin(iv) compounds. synthesis and structure of nitratotriphenyl(triphenylphosphine oxide)tin(iv)

A nitrato-complex of organotin(IV) containing triphenylphosphine oxide, Sn(C₆H₅)₃(NO₃) [(C₆H₅)₃PO], has been synthesized and characterized by infrared spectroscopy and X-ray structural analysis. The compound crystallizes in space group P 1¯, with a = 11.817(6), b = 11.086(6), c = 12.471(6), α = 99.6(1),β = 90.8(1), γ = 97.8(1), Z = 2. The structure has been solved from X-ray diffractometer data by Patterson and Fourier methods and refined by least-squares calculations to R = 6.4% for 4301 independent reflections. The structure consists of discrete monomer units in which tin shows trigonal bipyramidal geometry.     

New catalytic systems for the manufacture of poly(aspartic acid)

Aspartic acid (I), when heated to a temperature in excess of 180 °C, undergoes a solid-state condensation polymerization to afford the useful polymeric intermediate known as poly(succinimide) (II). Treatment of poly(succinimide) with aqueous base, such as sodium hydroxide, affords sodium poly(α,β-DL-aspartate) (III) also known as thermal poly(aspartate) (TPA). Acid catalysts, such as phosphoric acid have been added to the aspartic acid to afford higher-molecular-weight poly(succinimide) than is obtained in the non-catalyzed polymerization. Recently, new sulfur-based catalysts have been disclosed for the polymerization of aspartic acid. The sulfur-containing catalysts provide a route to highly biodegradable, low-color poly(aspartate)s in the molecular weight range of 2 000 to 20 000. A comparison of biodegradability, molecular weight, and spectral characteristics of the poly(succinimide)s and poly(aspartate)s derived from the catalyzed and non-catalyzed polymerizations is presented.     

Efficient catalytic systems based on paramagnetic closo-ruthenacarboranes for the controlled synthesis of polymers

Novel catalytic systems were proposed for controlled radical polymerization of vinyl monomers. These systems are based on the paramagnetic (17-electron) closo-complex, namely, 3,3-(dppb)-3-Cl-closo-3,1,2-RuC₂B₉H₁₁ (1, dppb is 1,4-bis(diphenylphosphino)butane) and its mono(P-phenylene)- and di(P,P-ortho-phenylene)cycloboronated derivatives, namely, (R = H, n = 10 (2); R = Me, n = 8 (3)) and (4). With the polymerization of methyl methacrylate as an example, the effect of the steric hindrances in complexes 1?C4 on the synthesis and molecular-weight characteristics of the resulting polymers was analyzed. In the presence of aliphatic amines, the polymerization rate increases substantially and the catalyst concentration can be lowered without losing control of the process. The structure of 17-electron complex 3 in the solid state and its paramagnetic nature were confirmed by X-ray diffraction and ESR spectroscopy.     

Synthesis of a novel titanium complex catalyst and its catalytic performance for olefin polymerization

Russian Journal of Applied Chemistry - A phenoxy-ester Ti based complex of bis[5-methyl-3-trimethylsilyl phenyl salicylate]titanium(IV) dichloride was prepared for olefin polymerization. The...     

Sulfur(iv) reagents for the SuFEx-based synthesis of substituted sulfamate esters

Sulfur(vi) fluoride exchange chemistry has been reported to be effective at synthesizing valuable sulfur(vi) functionalities through sequential nucleophilic additions, yet oxygen-based nucleophiles are limited in this approach to phenolic derivatives. Herein, we report a new sulfur(iv) fluoride exchange strategy to access synthetically challenging substituted sulfamate esters from alkyl alcohols and amines. We also report the development of a non-gaseous, sulfur(iv) fluoride exchange reagent, N-methylimidazolium sulfinyl fluoride hexafluorophosphate (MISF). By leveraging the reactivity of the sulfur(iv) center of this novel reagent, the sequential addition of alcohols and amines to MISF followed by oxidation afforded the desired substituted sulfamates in 40–83% yields after two steps. This new strategy expands the scope of SuFEx chemistry by increasing the accessibility of underdeveloped –S(O)F intermediates for future explorations.

N-Methylimidazolium sulfinyl fluoride hexafluorophosphate (MISF) was developed as a solution-stable sulfur(iv) reagent to access substituted sulfamate esters using a sulfur(iv) fluoride exchange strategy.

Sulfur fluoride exchange (SuFEx) reagents have powerful applications in pharmaceuticals, chemical biology, and materials science.¹ The most commonly utilized reagents are sulfur(vi) compounds, such as sulfuryl fluoride (SO₂F₂) and its derivatives, that can be used to efficiently synthesize a wide range of functionalities through sequential nucleophilic additions (Fig. 1a).² Sulfamate esters are targets of particular interest as they display potential as anticancer agents and as a new class of antibiotics,³ as well as versatility as synthetic intermediates.⁴ Oxygen-based nucleophiles are limited to phenolic derivatives with sulfur(vi) SuFEx reagents, restricting their use in sulfamate ester syntheses. The reaction of aliphatic alcohols with SO₂F₂ leads to aliphatic fluorosulfate intermediates that are very unstable, and results in rapid substitution at the fluorosulfate alpha-position (Fig. 1b).^5,6O-Alkyl sulfamate esters (ROSO₂NH₂) are readily synthesized with alternatives to SuFEx-based methods,⁷ but the substituted analogues require harsh conditions, multiple steps, and long reaction times.⁸ For example, sulfur(vi) chloride reagents have been utilized in the syntheses of sulfur(vi) moieties, yet are limited due to their inherent instability and prevalent side reactions.^9,10 A fast, mild, and SuFEx-based approach to the syntheses of substituted alkyl sulfur(vi) motifs is, therefore, desired.Open in a separate windowFig. 1SuFEx chemistry for the syntheses of S(vi) functionalities. (a) Reported sulfur(vi) SuFEx approach to linking nucleophiles. (b) Limitations of sulfur(vi) reagents in accessing fluorosulfate intermediates. (c) This work. Use of novel sulfur(iv) SuFEx reagent followed by oxidation to access synthetically challenging sulfur(vi) motifs that are inaccessible with sulfur(vi) reagents.The aforementioned limitations of sulfur(vi) SuFEx reactions may be overcome by utilizing a novel approach involving sulfur(iv) fluoride reagents (Fig. 1d). The addition of an alkyl alcohol to a sulfur(iv) fluoride exchange reagent should readily form the corresponding fluorosulfite intermediate. In contrast to fluorosulfates, fluorosulfites 2 may be more reactive at the sulfur center than the alpha-position.¹¹ Therefore, the addition of a heteroatom nucleophile to the sulfur(iv) center of a fluorosulfite should be faster and more selective than the sulfur(vi) analogue. A subsequent oxidation of the sulfur(iv) center would then afford the desired sulfur(vi) motif. While the oxidation step limits the substrate scope, this strategy provides a route to substrates that were previously inaccessible.Thionyl fluoride (SOF₂), the sulfur(iv) analogue of SO₂F₂, has displayed versatile reactivity despite the relatively few studies on its use.^11,12 The initial addition of a heteroatomic nucleophile to thionyl fluoride has been reported to be an efficient protocol for achieving amino sulfinyl fluorides and fluorosulfites,¹³ yet further reactivity of these intermediates has not been reported. There are also several major drawbacks to its use, including safety hazards associated with handling the gaseous reagent.¹⁴ There is no literature precedence for non-gaseous sulfur(iv) derivatives of thionyl fluoride. Therefore, a non-gaseous derivative that maintains the fundamental reactivity of SOF₂ is essential for the broad adoption of this class of sulfur(iv) reagents.     

Multicentered self-immobilized ethylene polymerization catalysts based on functionalized titanium halide salicylaldiminate complexes for the synthesis of ultra-high-molecular-weight polyethylene

Specific features of ethylene polymerization using a new group of catalytic systems based on ten methylalumoxane-activated titanium halide salicylaldiminato complexes functionalized with ??-vinylalkoxy groups and containing tert-butyl substituents in the phenoxide moiety were studied. The catalytic activity of the new group of activated complexes is strongly affected by the position of the ??-vinylalkoxy functional group and by the number and position of substituents in the phenoxide moiety. These factors determine the ratio of the homogeneous and heterogeneous steps of the polymerization as a result of the catalyst self-immobilization onto the polymer formed, and also the molecular characteristics of the polymer obtained at 20, 40, and 60°C and ethylene pressure of 0.4 MPa. The possibility and conditions of preparing ultra-high-molecular-weight polyethylene with improved morphology were revealed.     

New thermoplastic poly(thiourethane-urethane) elastomers based on hexane-1,6-diyl diisocyanate (HDI)

Two series of new thermoplastic poly(thiourethane-urethane) elastomers (EPTURs), with different hard-segment content (40–60 wt%), were synthesized by a one-step melt polymerization from poly(oxytetramethylene) diol (PTMO) of $ \overline{M}_{\text{n}} $  = 1,000 g mol^?1 or poly(hexamethylene carbonate) diol (PHCD) of $ \overline{M}_{\text{n}} $  = 860 g mol^?1 as a soft segment, hexane-1,6-diyl diisocyanate and (methylenedi-1,4-phenylene)dimethanethiol as a chain extender at the NCO/(OH + SH) molar ratio of 1. The structures of all the EPTURs were examined by Fourier transform infrared spectroscopy (FTIR), atomic force microscopy and X-ray diffraction analysis. Their thermal behavior was investigated by means of differential scanning calorimetry and thermogravimetric analysis (TG). For the chosen polymers the gaseous products evolved during the decomposition process were analyzed by TG-FTIR. Moreover, physicochemical, adhesive and tensile properties as well as Shore A/D hardness were determined. The resulting high-molecular-mass EPTURs were stable up to 254–262 °C, as measured by the temperature of 1 % mass loss. They decomposed in three or four stages. The main decomposition products were carbonyl sulfide, isocyanate, carbon dioxide, aromatic hydrocarbons as well as aliphatic ethers and aldehydes (in PTMO series) and alcohols (in PHCD series). All the polymers showed partially crystalline structures, associated with crystallization of thiourethane hard segments. Their melting temperatures were in the range of 184–186 °C. The PTMO series EPTURs exhibited better low-temperature properties (glass-transition temperature in the range of ?64 to ?44 vs. ?26 to ?22 °C), but poorer tensile strengths (20–28 vs. 37–43 MPa). These EPTURs showed improved adhesive properties in comparison with their polyurethane analogs.     

Redistribution reactions in the ion source of a mass spectrometer of complexes of titanium (iv), tin (iv) and germanium (iv) with 8-quinolinolato and halo or ethoxy ligands

The relative intensities of peaks in the mass spectra of the compounds MX_4?nox_n (oxH = 8-quinolinol; n = 2; M = Ti; X = F, Cl, Br or OEt; M = Sn; X = F, Cl, Br or I; M = Ge; X = Cl or Br; n = 1; M = Ti; X = OEt) depend on the insertion temperature and the residence time of the sample in the mass spectrometer. In most cases ions which cannot arise by fragmentation of the respective molecular ions are observed. These ions arise from the ionisation and fragmentation of species which are due to redistribution reactions in the mass spectrometer. The fragmentation pattern of the compounds MX₂ox₂ (X = halogen), mainly involving loss of ligand radicals, is related to the common oxidation states of the metals and reflects the metal-halogen bond strength. The molecular ions of the compounds Ti(OEt)_4?nox_n (n = 0, 1 or 2) fragment by loss of intact ligand radicals.