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A series of mononuclear aryl-substituted cyclopentadienyl complexes [CpPh3LnCl2(Me3tach)] (Ln = Tb (4), Ln = Nd (5)), [CpPh2ArTbCl2(Me3tach)] (6), and [CpPh3LnCl2(Me3tacn)] (Ln = Tb (7), Ln = Nd (8...

A novel pathway is proposed for the formation of branched poly(ethylene phosphate)s during the coordination ring-opening polymerization (ROP) of ethylene phosphates catalyzed by a 2,6-di-tert-butyl-4-methylphenoxy (BHT) magnesium complex, [(BHT)Mg(μ-OBn)(THF)]2 (Mg1). Electron-donating fragments in the substituents at the P atom of the ethylene phosphates and the stability of chelate Mg complexes were hypothesized to drive the formation of ethylene phosphate macromonomers. This hypothesis was validated through a comparative experimental and theoretical study of the ROP reactivity of the ethylene phosphates with –O(CH2)nCOOMe (n = 1–3, 5), –CH2COOtBu, –OCHMeCOOMe, and –OCH2CONMe2 substituents (1–7). In good agreement with the results of theoretical modeling, glycolate- and lactate-substituted ethylene phosphates 1, 5, and 6 formed highly branched polymers, and the participation of the BHT-Mg glycolate intermediate in ROP was confirmed by the presence of –P(O)(OCH2COOMe)2 fragments in the homopolymer of 1. Notably, the reaction of amide-substituted 7 with Mg1 quantitatively afforded benzyl ethylene phosphate without subsequent ROP. The copolymerization of 1 with ethyl ethylene phosphonate furnished branched polymers, the architectures of which were determined by spectral and rheological studies. Consequently, new –OCH2COX substituted cyclic phosphates can be used as efficient branching (X = OR) or chain termination (X = NR2) agents.

Polylactides, polyglycolides and copolymers containing both glycolate and lactate fragments are biocompatible and biodegradable materials that can be used for environmentally friendly packaging, 3D printing, surgery, drug delivery and other applications. Here we present a first comparative study of a series of 1,4-dioxan-2,5-diones (glycolides: MeGL, iPrGL, iBuGL, BnGL, PhGL and MePhGL) that can be synthesized from natural L-α-hydroxy acids or L-α-amino acids. The formation of (R,R)(S,S)-MePhGL was confirmed by X-ray diffractometry and explained using density functional theory (DFT). We found that diester fragments are retained during the non-catalytic methanolysis of these compounds and that ring-opening regoiselectivity depends on the bulkiness of the substituents. Ring-opening polymerization, catalyzed by 1,5,7-triazabicyclo[4.4.0]undec-5-ene, yielded alkyl-substituted polyglycolides with given MWs. Controlled polymerization of PhGL was possible at low monomer/initiator ratios, while (R,R)/(S,S)-MePhGL formed oligomers and epimerized products. DFT modeling provided an explanation for the observed patterns based on the ease of enolization and the stability of the enolate-anions of phenyl-substituted glycolides. Solutions of MeGL, iPrGL, iBuGL, BnGL and PhGL homopolymers in hexafluoroisopropanol were electrospun into fibrous mats whose morphologies, mechanical characteristics, biodegradabilities and thermal properties varied widely and depended on the substituents on the glycolide.

Ultra-high molecular weight poly-α-olefins are widely used as drag reducing agents (DRAs) for pipeline transportation of oil and refined petroleum products. The synthesis of polyolefin DRAs is based on low-temperature Ziegler–Natta (ZN) polymerization of higher α-olefins. 1-Hexene based DRAs, the most effective at room temperature, typically lose DR activity at low temperatures. The use of 1-hexene copolymers with C8–C12 linear α-olefins appears to offer a solution to the problem of low-temperature drag reducing. The present work aims to develop two-stage synthesis of polyolefin DRAs that is based on selective oligomerization of ethylene in the presence of efficient chromium/aminodiphosphine catalysts (Cr-PNP), followed by polymerization of the olefin mixtures, formed at oligomerization stage, using efficient titanium–magnesium ZN catalyst. We have shown that oligomerization of ethylene in α-olefin reaction media proceeds faster than in saturated hydrocarbons, providing the formation of 1-hexene, 1-octene, and branched C10 and C12 olefins, the composition and the ratio of the reaction products depended on the nature of PNP ligand. Oligomerizates were used in ZN polymerization ‘as is’, without additional treatment. Due to branched character of C10+ hydrocarbons, formed during oligomerization of ethylene, resulting polyolefins demonstrate higher low-temperature DR efficiency at low polymer concentrations (~1 ppm) in comparison with benchmark polymers prepared from the mixtures of linear α-olefins and from pure 1-hexene. We assume that faster solubility and more efficient solvation of the polyolefins, prepared using ‘tandem’ ethylene-based process, represent an advantage of these type polymers over conventional poly(1-hexene) and linear α-olefin-based polymers when used as ‘winter’ DRAs.

A new terbium(III) complex with a (3,4-diphenyl)(2-methylthienyl)cyclopentadienyl ligand was synthesized. Single-crystal X-ray analysis revealed a binuclear biscyclopentadienyl complex with a [TbCl2K]2 core. Luminescence properties of the terbium complex were analyzed.

In bone surgery and orthopedics, bioresorbable materials can be helpful in bone repair and countering post-op infections. Explicit antibacterial activity, osteoinductive and osteoconductive effects are essential to achieving this objective. Nonwoven electrospun (ES) fibers are receiving the close attention of physicians as promising materials for wound dressing and tissue engineering, potentially, in high contrast with dense materials, ES mats hamper regeneration of the bone extracellular matrix to a lesser extent. The use of the compositions of inherently biodegradable polyesters (poly(ε-caprolactone) PCL, poly(lactoglycolide), etc.), calcium phosphates and antibiotics is highly prospective, but the task of forming ES fibers from such compositions is complicated by the incompatibility of the main organic and inorganic ingredients, polyesters and calcium phosphates. In the present research we report the synthesis of hydroxyapatite (HAp) nanoparticles with uniform morphology, and demonstrate high efficiency of the block copolymer of PCL and poly(ethylene phosphoric acid) (PEPA) as an efficient compatibilizer for PCL/HAp mixtures that are able to form ES fibers with improved mechanical characteristics. The materials obtained in the presence of vancomycin exhibited incremental drug release against Staphylococcus aureus (St. aureus).

It is well known that ring-opening polymerization (ROP) of sterically unhindered cyclic ethylene phosphates, initiated by both organocatalysts and coordination catalysts, is accompanied by transesterification (TE) even at subzero temperatures. To clarify this phenomenon from the mechanistic point of view, we calculated (DFT, B3PW91/DGTZVP) the reaction profiles of the ROP for 2-methoxy-1,3,2-dioxaphospholane-2-oxide (methyl ethylene phosphate, MeOEP) and of the transesterification processes for poly(MeOEP) and trimethyl phosphate (TMP) in the presence of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) organocatalyst. We found that the free activation energy of TE is substantially higher (10–13 kcal/mol) than the ROP activation barrier. To verify the calculation results, we investigated the chemical behavior of low molecular weight trimethyl phosphate (TMP) in the TBD-catalyzed polymerization of MeOEP. We demonstrated that TMP was not affected by transesterification, which correlates with the calculation results. However, we found that the polymerization of MeOEP in the presence of TMP leads to the formation of linear poly(MeOEP) with given Pn and narrow MWD even at >99% monomer conversion degree. A similar pattern was revealed for the synthesis of poly(MeOEP) with the coordination catalyst of aryloxy-alkoxy magnesium complex [(BHT)Mg(μ-OBn)(THF)]2 (BHT = 2,6-di-tert-butyl-4-methylphenoxy). To explain the difference in the chemical behavior of TMP and polyphosphate, we assumed that poly(MeOEP) in the solution represents a dense globule, which leads to a decrease in the entropy of transesterification. To confirm this assumption, we studied the solution behavior of poly(MeOEP) in CHCl3 and in TMP. Both CHCl3 and TMP were found to be poor solvents for poly(MeOEP) in terms of KMH solution theory (α = 0.53 and 0.33, respectively). We assume that it is the conformation of the polymer in the solution that determines the tendency of the polyphosphate towards transesterification.

Complexes [(1,2,4-Ph3C5H2)2NdCl2K(THF)2]2 (Nd1), {[1,2-Ph2-4-(4-MeOC6H4)C5H2]2NdCl2K(THF)2}2 (Nd2), {[1,2-Ph2-4-(2-MeOC6H4)C5H2]2NdCl2[K(THF)4]}(THF)0.5 (Nd3), and [(1,2,4-Ph3C5H2)2TbCl2K]2 (Tb1) h...

The modification of isoprene, butadiene, and styrene (co)polymers has been carried out for the first time with the use of diene polar monomers based on myrcene. Copolymers involving up to ∼10 mol % polar units have been synthesized. A method of synthesis of functional monomers on the basis of large-tonnage natural raw material (turpentine) makes them available and promising compounds for industrial use in the synthesis of diene and styrene diene rubbers.

Despite the world&rsquo, s combined efforts, human immunodeficiency virus (HIV), the causative agent of AIDS, remains one of the world&rsquo, s most serious public health challenges. High genetic variability of HIV complicates the development of anti-HIV vaccine, and there is an actual clinical need for increasing the efficiency of anti-HIV drugs in terms of targeted delivery and controlled release. Tenofovir (TFV), a nucleotide-analog reverse transcriptase inhibitor, has gained wide acceptance as a drug for pre-exposure prophylaxis or treatment of HIV infection. In our study, we explored the potential of tenofovir disoproxil (TFD) adducts with block copolymers of poly(ethylene glycol) monomethyl ether and poly(ethylene phosphoric acid) (mPEG-b-PEPA) as candidates for developing a long-acting/controlled-release formulation of TFV. Two types of mPEG-b-PEPA with numbers of ethylene phosphoric acid (EPA) fragments of 13 and 49 were synthesized by catalytic ring-opening polymerization, and used for preparing four types of adducts with TFD. Antiviral activity of [mPEG-b-PEPA]TFD or tenofovir disoproxil fumarate (TDF) was evaluated using the model of experimental HIV infection in vitro (MT-4/HIV-1IIIB). Judging by the values of the selectivity index (SI), TFD exhibited an up to 14-fold higher anti-HIV activity in the form of mPEG-b-PEPA adducts, thus demonstrating significant promise for further development of long-acting/controlled-release injectable TFV formulations.

Poly(ethylene phosphoric acid)s (PEPA)s of different compositions, namely homopolymers, and diblock and triblock copolymers containing poly(ethylene glycol) monomethyl ether, l -lactide, and e-caprolactone blocks, can be quantitatively obtained by mild thermolysis of polymers based on tert-butyl ethylene phosphate in aqueous media at 80 °C. Thermolysis of poly(tert-butyl ethylene phosphate) in the presence of sodium acetate gave a PEPA with a narrow molecular weight distribution (Ð = 1.10). The salt-like reaction product can be concentrated without the formation of three-dimensional gels. All starting poly(tert-butyl ethylene phosphate) containing homopolymers and block copolymers were effectively prepared with phenolate–Mg catalysts, i.e., [(BHT)MgBu(THF)]2 and [(BHT)Mg(OBn)(THF)]2 (BHT = 2,6-di-tert-butyl-4-methylphenolate). In the synthesis of polyphosphate–polyester block copolymers, the polyphosphate macromonomer inhibits further polymerization of e-caprolactone. We therefore failed to obtain a copolymer BnO(tBuOEP)n-b-(eCL)mH using a coordination Mg catalyst.

We elaborated a synthetic approach to a new family of PNP ligands that involves assembling sequential molecules based on the rigid 5,6-dihydrodibenzo[c,e][1,2]azaphosphinine backbone (−Z−). This approach allowed us to obtain PNP-type ligands of the general formula Ar2P–Z–Ar′ (Ar, Ar′ = Ph, o-MeOC6H4) with high yields and without the formation of PPN byproducts. Ar2P–Z–Ar′/Cr(acac)3 (acac = acetylacetonate) adducts activated by modified methylalumoxane (MMAO-12) effectively catalyzed ethylene oligomerization; the number of ortho-methoxyphenyl fragments n controls the direction of the process, from slow polymerization (n = 0) to rapid oligomerization (n = 3), thereby producing a mixture of 1-hexene and 1-octene in ∼2:1 ratio with very low formation of polyethylene (∼0.6%).

Ring-opening polymerization (ROP) of cyclic esters (lactones, lactides, cyclic carbonates and phosphates) is an effective tool to synthesize biocompatible and biodegradable polymers. Metal complexes effectively catalyze ROP, a remarkable diversity of the ROP mechanisms prompted the use of density functional theory (DFT) methods for simulation and visualization of the ROP pathways. Optimization of the molecular structures of the key reaction intermediates and transition states has allowed to explain the values of catalytic activities and stereocontrol events. DFT computation data sets might be viewed as a sound basis for the design of novel ROP catalysts and cyclic substrates, for the creation of new types of homo- and copolymers with promising properties. In this review, we summarized the results of DFT modeling of coordination ROP of cyclic esters. The importance to understand the difference between initiation and propagation stages, to consider the possibility of polymer–catalyst coordination, to figure out the key transition states, and other aspects of DFT simulation and visualization of ROP have been also discussed in our review.

An effective method of 1-hexene polymerization in fluorous reaction media has been developed. When using perfluorinated compounds (FCs) as a solvent, the process, catalyzed by highly active titanium-magnesium catalysts modified with 3,3-bis(methoxymethyl)pentane (BMMP) as an electron-donor, proceeds as a precipitation polymerization, and the reaction products represent highly stereo- and regioregular poly(1-hexene)s in the form of microparticles. In freons, polymerization can be carried out at sub-zero temperatures with monomer conversion up to 50% within 1 h and the formation of UHMW poly(1-hexene)s with Mn ∼2·106 Da. The polymers prepared in FCs demonstrate a high drag reducing effect (up to 40% in n-heptane for 0.25 ppm concentration), exceeding the previously described UHMW poly(1-hexene)s. Polymerization products after mixing with rapeseed oil form stable dispersions of ready-to-use drag reducing agents (DRAs) for pipeline oil transportation.

An original approach to α-olefin oligomerization as well as novel thermally stable zirconocene catalysts for use in such reactions has been elaborated. The method reported allows the achievement of fractions of lightweight α-olefin oligomers up to 90% yields without considerable formation of byproducts like internal alkenes, alkanes, and higher oligomers. Trimers, tetramers, and pentamers of 1-hexene, 1-octene, and 1-decene were isolated as individual compounds and were hydrogenated. Viscosity characteristics of the isolated saturated and unsaturated hydrocarbons have been studied at various temperatures. The isolated saturated oligomers of 1-octene and 1-decene outperform the traditional electrophilic oligomerization products in terms of viscosity indexes, pour points, and low-temperature viscosity.

A new low molecular mass organic gelator based on tri-tert-butylates Glu-Urea-Lys and Fmoc-capped di-L-Phe-containing hexaamide (tri-tert-butyl (10S,13S,31S,35S)-10,13-dibenzyl-1-(9H-fluoren-9-yl)-3,9,12,15,18,25,33-heptaoxo-2-oxa-4,8,11,14,19,26,32,34-octaazaheptatriacontane-31,35,37-tricarboxylate, 9) was synthesized and examined for the ability to gelate various organic solvents (dichloromethane (DCM), chlorophorm, methanol, acetonitrile and acetonitrile/water mixtures, ethyl acetate). The microstructure of the obtained gels was studied using scanning electron microscopy (SEM). It was shown that the morphologies of the xerogels, formed by the slow drying of the corresponding organogels, differ for different solvents. For example, xerogels from DCM showed the layered slab structures with widths and lengths to hundreds of micrometers, but xerogels in ethanol exhibit networks composed of entwined fibers. Based on FTIR, 1H NMR and UV-vis data, the gelator molecules are aggregate via N–H/O hydrogen bonding, hydrophobic interaction and π-π-staking.

In recent decades, biodiesel has been explored as a prospective comparable fuel to petroleum diesel for compression ignition engines. However, several drawbacks have limited the wide application of biodiesel as motor fuel, and the poor cold-flow property is one of the major problems. This problem is compounded by the diversity of the biodiesel characteristics arising from a variety of chemical compositions of biodiesel from different sources. Among the methods investigated to improve the cold-flow properties of biodiesel, the use of additives seems highly promising. Despite the significant number of publications, the potential of this method is still far from having been completely discovered or exploited. In the present review, we briefly describe the sources, chemical composition, and physico-chemical characteristics of the main types of biodiesel. Next, we discuss the examples of the use of different polymer additives for the improvement of the cold-flow characteristics of biodiesel and biodiesel/petroleum diesel blends. Additionally, we tried to assess the prospects of the polymer additives to enhance biodiesel performance. The main conclusion of this survey is that innovative and high-efficiency cold-flow improvers for biodiesel should be further developed.

The binuclear complex bis(2,6-di-tert-butyl-4-methylphenolato)-1κO,2κO-(1,2-dimethoxyethane-1κ2 O,O′)bis(μ-phenylmethanolato-1:2κ2 O:O)(tetrahydrofuran-2κO)dimagnesium(II), [Mg2(C7H7O)2(C15H23O)2(C4H8O)(C4H10O2)] or [(BHT)(DME)Mg(μ-OBn)2Mg(THF)(BHT)], (I), was obtained from the complex [(BHT)Mg(μ-OBn)(THF)]2 by substitution of one tetrahydrofuran (THF) molecule with 1,2-dimethoxyethane (DME) in toluene (BHT is O-2,6- t Bu2-4-MeC6H4 and Bn is benzyl). The trinuclear complex bis(2,6-di-tert-butyl-4-methylphenolato)-1κO,3κO-tetrakis(μ-2-methylphenolato)-1:2κ4 O:O;2:3κ4 O:O-bis(tetrahydrofuran)-1κO,3κO-trimagnesium(II), [Mg3(C7H7O)4(C15H23O)2(C4H8O)2] or [(BHT)2(μ-O-2-MeC6H4)4(THF)2Mg3], (II), was formed from a mixture of Bu2Mg, [(BHT)Mg( n Bu)(THF)2] and 2-methylphenol. An unusual tetranuclear complex, bis(μ3-2-aminoethanolato-κ4 O:O:O,N)tetrakis(μ2-2-aminoethanolato-κ3 O:O,N)bis(2,6-di-tert-butyl-4-methylphenolato-κO)tetramagnesium(II), [Mg4(C2H6NO)6(C15H23O)2] or Mg4(BHT)2(OCH2CH2NH2)6, (III), resulted from the reaction between (BHT)2Mg(THF)2 and 2-aminoethanol. A polymerization test demonstrated the ability of (III) to catalyse the ring-opening polymerization of ∊-caprolactone without activation by alcohol. In all three complexes (I)–(III), the BHT ligand demonstrates the terminal κO-coordination mode. Complexes (I), (II) and (III) have binuclear rhomboid Mg2O2, trinuclear chain-like Mg3O4 and bicubic Mg4O6 cores, respectively. A survey of the literature on known polynuclear Mg x O y core types for ArO–Mg complexes is also presented.

This paper describes our recent results in the field of zirconocene-catalyzed α-oltfin transformations, and focuses on questions regarding the reaction mechanism, rational design of zirconocene pre-catalysts, as well as prospective uses of α-olefin products. It has been determined that a wide range of α-olefin-based products, namely vinylidene dimers, oligomers and polymers, can be prepared via catalysis by zirconocene dichlorides, activated by a minimal (10–20 eq.) amount of MAO. We assumed that in the presence of minimal quantities of MAO, various types of zirconocene catalysts form different types of catalytic particles. In the case of bis-cyclopentadienyl complexes, the reactive center is formed under the influence of R2AlCl, which makes the chain termination via β-hydride elimination significantly easier, with α-olefin dimers being formed as the primary product. Bis-indenyl complexes and their heteroanalogues, form stable cationic catalytic particles and effectively catalyze the polymerization. Mono-indenyl and mono-substituted bis-cyclopentadienyl-ansa complexes catalyze α-olefin oligomerization. Effective catalysts of dimerization, oligomerization and polymerization of α-olefins in the presence of minimal MAO quantities are proposed. Prospects of using α-olefin dimers, oligomers and polymers in the synthesis of branched hydrocarbon functional derivatives (dimers), high quality, low viscosity motor oils (oligomers), and thickeners and absorbents (polymers) are examined.

A number of mono-alkylphosphinic acids RCH2CH2CH(R)CH2P(O)(H)OH 8–12 were obtained via interaction of α-olefin vinylidene dimers RCH2CH2C(R)CH2 3–7 (R = n-butyl, 3, 8; isobutyl, 4, 9; n-octyl, 5, 10; isopropyl, 6, 11; cyclohexyl, 7, 12) with H3PO2 in an isopropanol medium at 90 °C. Hydrophosphinylation of 3 by 8 or PhPO2H2 at 140 °C resulted in disubstituted acids 13 and 14. Alkyl-methylphosphinic acids 15–19 and functionalized alkylphosphinic acids 20–22 have been synthesized via interaction of silyl ethers of mono-alkylphosphinic acids 8–12 with MeI, (2-chloromethyl)pyridine, acrylic acid or acrylamide. Non-catalytic hydroalumination of 3 with subsequent interaction with PCl3 and oxidation with SO2Cl2 led to the phosphonic acid anhydride, which was further used to obtain alkylphosphonic acids 23 and 24. It has been found that phosphinic acids 8–12 surpass di(2-ethylhexyl)phosphoric acid (extractant P204) in non-selective Ln3+ extractability (Ln = La, Pr, Nd, Dy and Lu). Significantly higher selectivity for heavy lanthanide extraction (Ln = Dy, Lu), compared to that of P204, is achieved by using a minimal excess of disubstituted phosphinic acids 13–24. Acid 13, which contains two branched substituents, demonstrated unique selectivity in the extraction of Lu in the presence of the other lanthanides. Dialkylphosphinic acids 16–18 and alkylarylphosphinic acid 14 possess a significant potential for the Pr/Nd pair separation. Taking into account the availability of 8–24 and the structural variability of the initial α-olefin dimers 3–7, the newly obtained compounds represent a promising group of rare-earth element extractants.

We report here that the heteroleptic BHT-Mg(OR) complex, i.e. [(BHT)Mg(OBn)(THF)]2 (Mg3), represents an effective and versatile ring-opening polymerisation (ROP) catalyst for several cyclic ethylene phosphate monomers (CEPMs), such as ethylene phosphates with methoxy- (MeOEP, 1), isopropoxy- (iPrOEP, 2), and tert-butoxy- (tBuOEP, 3) substituents, N,N-diethyl ethylene phosphoramidate (Me2NEP, 4) as well as ethyl (EtPPn, 5) and tert-butyl (tBuPPn, 6) ethylene phosphonates. Mg3 retains its catalytic activity over a broad temperature range from −50 to 100 °C and efficiently carries out the fast and controlled polymerisation of CEPMs with sterically unhindered alkoxy groups with less than 1% chain branching even at near-complete conversion. Compared with ROP catalysed by 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), Mg3 performs much better in the polymerisation of CEPMs with bulky groups and of monomers sensitive to strong nucleophiles, such as tBuOEP.

An efficient approach to copolymers of glycolic and lactic acids applied in biomedical materials was developed using ring-opening polymerization catalysts based on alkoxy complexes of ‘biometals’ (Mg, Al, and Zn) and 3-methyl- 1,4-dioxane-2,5-dione and glycolide as comonomers.

Zirconocene-mediated selective dimerization of &alpha, olefins usually occurs when precatalyst (&eta, 5-C5H5)2ZrCl2 is activated by minimal excess of methylalumoxane (MAO). In this paper, we present the results of density functional theory (DFT) simulation of the initiation, propagation, and termination stages of dimerization and oligomerization of propylene within the framework of Zr-Al binuclear mechanism at M-06x/DGDZVP level of theory. The results of the analysis of the reaction profiles allow to explain experimental facts such as oligomerization of &alpha, olefins at high MAO/(&eta, 5-C5H5)2ZrCl2 ratios and increase of the selectivity of dimerization in the presence of R2AlCl. The results of DFT simulations confirm the crucial role of the presence of chloride in the selectivity of dimerization. The molecular hydrogen was found in silico and proven experimentally as an effective agent that increases the rate and selectivity of dimerization.

Main methods for the polymerization of higher α-olefins (1-hexene, 1-octene, and 1-decene) with the formation of high molecular weight products, key properties of poly-α-olefins from the viewpoint of their use as drag reducing agents in the transportation of petroleum and petroleum products, as well as the challenges and prospects of the production of these important functional materials of the petroleum industry have been considered.

New mono- and bis-cyclopentadienyl neodymium ate -complexes, bearing phenyl-substituents in the cyclopentadienyl ring, have been synthesized: KNdCp′Cl 3 (thf) x (Cp′ = 1,3-Ph 2 C 5 H 3 ( 1 ), 1,2,4-Ph 3 C 5 H 2 ( 2 )) and KNdCp′ 2 Cl 2 (thf) x (Cp′ = 1,3-Ph 2 C 5 H 3 ( 3 ), 1,2,4-Ph 3 C 5 H 2 ( 4 ), 1,2-Me 2 -4-PhC 5 H 2 ( 5 ), 1,2-Ph 2 -4-(4-MeO-C 6 H 4 )C 5 H 2 ( 6 )). Their catalytic activity has been studied in ethylene oligomerization process in the presence of Bu 2 Mg as a chain transfer reagent with the Nd:Mg molar ratios being of 1:20, 1:40 or 1:80. Complex 4 exhibits catalytic activity close to the activity of the known complex [(C 5 Me 5 ) 2 NdCl 2 Li(OEt 2 ) 2 ] ( 7 ). The complex 6 has demonstrated the best catalytic activity among all studied complexes. Using selected complexes 2 , 4 and 6 as pre-catalysts, terminal iodo-functionalized oligoethylenes have been prepared. Obtained iodooligoethylenes have been studied by 1 H NMR technique and MALDI mass-spectrometry with preliminary derivatization, demonstrating 70–90% of functionalization. Crystal structures of ate -complexes [{(1,2,4-Ph 3 C 5 H 2 )Nd(thf)} 2 Cl 5 K] 2 (toluene) 4 ( 2a ), [(1,2,4-Ph 3 C 5 H 2 ) 2 NdCl 2 K(thf) 0.53 (1,4-dioxane) 1.47 ] 2 (dioxane) ( 4a ) and {[{1,2-Ph 2 -4-(4-MeO-C 6 H 4 )C 5 H 2 } 2 NdCl 2 K] 2 (1,4-dioxane)}(toluene) 4 have been studied by the single crystal X-ray diffraction.

The phase state and rheological properties of dimethyl sulfoxide (DMSO) solutions of a series of acrylonitrile-based copolymers (PAN), which were obtained by suspension polymerization and synthesized in supercritical CO2, have been studied. For PAN-DMSO (plus water) solutions, a bimodal amorphous phase equilibrium takes place at ~78°C. Comparison of the rheological behavior of homo- and copolymer solutions has shown that the presence of carboxylate ion(s) in the macromolecular chain leads to supramolecular structure formation. Small additions of non-solvent (water) enhance the viscoelasticity of the solution, whereas a large amount of water results in gel formation; beyond a certain threshold of water concentration, macroscopic phase separation takes place. Addition of carbon nanotubes into the solution does not change their phase state or rheological behavior. Application of mechanical forces to concentrated solutions may cause specific phase separation without the addition of a non-solvent.

The ring-opening polymerizations (ROP) of five-, six-, and seven-membered ring cyclic substrates, as well as the transesterification of acyclic esters, with 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as a catalyst precursor in the presence of methanol as an initiator were investigated using density functional theory calculations at the B3LYP/6–311G(d) level of theory. The calculated energy barriers for the ROP are in the range from 12.5 to 21.5 kcal/mol. By analyzing the energy profiles, the overall polymerization process can be classified into exergonic for trimethylene carbonate, tetramethylene carbonate, caprolactone and 1,4-dioxane-2,5-dione, almost athermic for valerolactone, energetically unfavorable for 1,4-dioxanone, and thermodynamically forbidden for ethylene carbonate and gamma-butyrolactone. The study of the kinetics of ROP of cyclic substrates and transesterification of acyclic esters using the TBD—benzyl alcohol catalyst demonstrated that the experimentally determined rate constants for the reactions of cyclic substrates are qualitatively correlated with the calculated activation barriers. It was also experimentally found that TBD efficiently catalyzes the irreversible cyclization to give ethylene carbonate and gamma-butyrolactone, the catalyst productivity being 2–3 orders of magnitude higher than that of conventional basic catalysts. The obtained results confirm that the donor–acceptor mechanism is common for different ester-type substrates.

Synthesis of titanium–magnesium nanocatalyst in a high-pressure reactor under the conditions modeling the industrial conditions was studied. A laboratory scale plant including the units for the product synthesis, washing, and filtration was developed. The effect of elevated pressure (10–90 atm) on the process course, on the properties of the catalyst formed, and on the isoprene polymerization was studied for the first time. An increase in pressure leads to an increase in titanium incorporation into the catalyst from 1.52 to 2–2.3 wt % and simultaneously to an increase in the trivalent titanium content to 81 wt %. The titanium–magnesium nanocatalyst with such properties exhibits enhanced performance in isoprene polymerization without deteriorating the polymer microstructure. The development of the catalyst synthesis procedure on the laboratory scale plant will allow pilot-scale modeling of this process in the future.

Organophosphate-chloride complexes [{(2,6-iPr2C6H3-O)2POO}2LnCl(CH3OH)4]&middot, 2CH3OH, Ln = Nd (1), Eu (2), Gd (3), and Tb (4) have been obtained and structurally characterized. Their reaction with 2,2&prime, 6&prime, 2&Prime, terpyridine leads to the formation of 1:1 adducts ([{(2,6-iPr2C6H3-O)2POO}2LnCl(terpy)(H2O)2(CH3OH)], Ln = Eu (5), Gd (6), Tb (7) with exception of Nd, where tris-diisopropylphenylphosphate complex [{(2,6-iPr2C6H3-O)2POO}3Nd) (terpy)(H2O)(CH3OH)] (8) was obtained due to the ligand metathesis. A bright luminescence observed for the Eu and Tb organophosphate complexes is the first example of an application of organophosphate ligands for 4f-ions luminescence sensitization. Photophysical properties of all complexes were analyzed by optical spectroscopy and an energy transfer scheme was discussed. A combination of two types of ligands into the coordination sphere (phosphate and phenanthroline) allows designing the Eu surrounding with very high intrinsic quantum yield QEuEu (0.92) and highly luminescent Ln complexes for both visible and near-infrared (NIR) regions.

Both Group 4 poly-α-olefin (PAO) and Group 5 ester oil basestocks are used in formulations of synthetic engine oils, transmission fluids, and lubricants with leading characteristics such as low viscosity (providing fuel saving), high stability, and environmental safety. The modern technologies of the production of PAOs use catalytic oligomerization of α-olefins, which is complicated by the formation of low-molecular-weight α-olefin dimers (methylenealkanes) as imminent side products. The use of methylenealkanes as raw materials for the synthesis of Group 5 base stocks appears to be highly promising. In the present work, we report the use of methyl 3-butylnonanoate and methyl 3-hexylundecanoate, the products of catalytic methoxycarbonylation of hex-1-ene and oct-1-ene dimers, in the synthesis of two series of branched isomeric esters. These esters demonstrated excellent rheological behavior and may be considered as low-viscosity engine oils with leading characteristics.

The zirconocene complexes L2ZrCl2 (L = C5H5, C5H4Me, Ind, C5Me5; L2 = rac-Me2C(2-Me-4-But-C5H2)2, meso-Me2C(2-Me-4-But-C5H2)2, rac-Me2C(3-But-C5H3)2, rac-Me2C(Ind)2, rac-Me2Si(Ind)2, and rac-C2H4(Ind)2) were tested as catalysts in alkene hydroalumination by the isobutylalanes XAlBui2 (X = H, Cl, Bui). A low-temperature NMR spectroscopy study on the structure and dynamics of Zr,Al intermediates formed in the L2ZrCl2–XAlBui2 systems showed that the intra- and intermolecular exchange in the bimetallic clusters, controlled by the steric factor of the η5 ligand and organoaluminum compound nature, determines the activity of the whole catalytic system.

A series of bis(o-hydroxyphenyl)quinolines have been prepared, starting from 2,8-dibromoquinoline. Reaction of these new ligand precursors with group 4 tetrabenzyl complexes MBn4 results in benzyl substitution of the azine fragment with the formation of amide complexes (M = Ti) or amine complexes with an N–H fragment coordinated to the metal (M = Zr, Hf). The third structural type—Zr complexes where the aromatic system of the precursor remains intact—can be prepared through the reaction of the bis(o-hydroxyphenyl)quinolones with 4 mol of methyllithium, followed by ZrCl4. The new complexes result in active polymerization catalysts when activated with MAO/borate cocatalysts on silica supports, resulting in polyethylene copolymers with very high molecular weights and multimodal MWDs.

A new family of lanthanide complexes with di- and triphenylacetate ligands was prepared from LnCl3. Dimeric diphenylacetates were the only isolated products of the reaction between LnCl3 (Ln = La, ...

A number of 2-methyl-4-aryl-5-methoxy-6-alkylindenes and C2-symmetric Me2Si-bridged ansa-zirconocenes based on them were synthesized. Zirconocenes were obtained by means of highly effective and scalable racemo-selective synthetic approach based on the use of a Zr tert-butyl amide complex. The structure of μ-(bis-[η5-6-tert-butyl-5-methoxy-2-methyl-4-tert-butylphenyl-1H-inden-1-yl]dimethylsilanediyl)dichlorozirconium(IV) (14) has been established with X-ray analysis. The introduction of a methoxy group into the indenyl fragment of zirconocene significantly improved its catalytic performance (i.e., its activity, stereoselectivity, molecular mass potential, and thermal stability) in the polymerization and copolymerization of propylene in comparison with the benchmark Spaleck-zirconocene. The role of the methoxy group is proposed to stabilize the cationic catalytic intermediates, which was confirmed using DFT calculations.