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A detailed study of the reaction of CF

Structures of exo- and endo-complexes of fullerene C60 with zero-valent Fe0, in which the metal is localized inside and outside fullerene molecule, respectively, have been strictly revealed with the DFT method. The complexes structures (η6- and η2-, in which the iron atom is localized at the six-membered ring or double bond between the five- and six-membered rings or between six-membered rings) have been optimized for triplet, and their energy has been lower than for the corresponding singlet and quintet. Geometry and thermodynamic parameters of the complexes have been established.

International audience; Metalcyclopentadienyl complexes (MCp) (M = Fe, Ru, Os) bound to the large polyaromatic hydrogenated hydrocarbon (PAH) CH used as a model for pristine graphene have been studied using a density functional theory (DFT) generalized gradient approximation (PBE functional) to reveal their structural features and dynamic behavior. The inter-ring haptotropic rearrangements (IRHRs) for these complexes were shown to occur via two transition states and one intermediate. The energy barriers of the η ⇌ η IRHRs of the (MCp) unit were found to be 30, 27, and 29 kcal/mol for M = Fe, Ru, and Os, respectively. These values are significantly lower than the values found previously for smaller PAHs. Both polar and nonpolar solvents were found not to affect significantly the energy barrier heights. Investigated transition metal complexes could be used in general as catalysts in the design of novel derivatives or materials with promising properties. Metalcyclopentadienyl complexes (MCp) of PAHs show catalytic properties mainly due to their structural details as well as their important characteristic of inter-ring haptotropic rearrangement. IRHRs take place usually by intramolecular mechanisms. During IRHRs, the ML organometallic groups (OMGs) undergo shifting along the PAH plane and could coordinate additional reagents, which is important for catalysis. Large PAHs such as graphene, fullerenes, and nanotubes possess intrinsic anticancer activity, and numerous arene complexes of Ru and Os have been proven to have anticancer properties as well. We suppose that coordinating Ru or Os to very large PAHs could synergistically increase the anticancer activity of resulting complexes.

A new yttrium(iii) complex with the pincer type bis(phosphinophenyl)amide ligand was synthesized and its activity and selectivity in the isoprene polymerization reaction was studied. An ultrahigh molecular weight polyisoprene with a > 99% content of 1,4-cis units was obtained.

A new approach to the synthesis of 3-nitroindoles using palladium-catalyzed arylation of nitromethane with N-(2-bromoaryl)imidates was developed. A convenient and rapid method for cyclization of ethyl N-(2-nitromethylaryl)acetimidates to 2-methyl-3-nitro-1H-indoles was proposed.

The polymerization of commercial strained cycloalkene, 5-ethylidene-2-norbornene, in the presence of Pd–N-heterocyclic carbene complexes (two of which are synthesized for the first time) containing phosphine or pyridine ligands is studied. Upon activation with borate Na+[B(3,5-(CF3)2C6H3)4)]–, the studied Pd complexes catalyze the polymerization of 5-ethylidene-2-norbornene according to the addition scheme. Polymerization proceeds selectively and involves only the endocyclic (norbornene) double bond of the monomer, while the exocyclic (ethylidene) double bond remains unaffected. Pd–N-heterocyclic carbene complexes with phosphine ligands are inactive in polymerization, while similar complexes with 3-chloropyridine ligands show a higher activity. Two new Pd complexes are synthesized.

Borylation of arenes with bis(pinacolato)diboron catalyzed by sterically encumbered NHC platinum complexes proceeds predominantly at ortho-position even in the absence of a directing group (o : m : p ratio up to 10: 3: 1). The similar borylation with pinacolborane would proceed less selectively.

Using the commercial derivative of norbornene—5-ethylidene-2-norbornene—a series of three isomeric homopolymers with different structure of the backbone is synthesized, and the effect of the chain structure on the gas-transport behavior of polynorbornenes is studied. The gas-transport characteristics of the polymers are presented together with data on the conformation properties of molecules of addition and metathesis polynorbornenes. The effect of the structure of side substituents on the equilibrium rigidity of addition polynorbornenes is confirmed by the example of poly(5-ethylidene-2-norbornene) and poly(5-vinyl-2-norbornene).

International audience; Inter-ring haptotropic rearrangements (IRHRs) of different types are well-known phenomena in organometallic and catalytic chemistry. So far, they are reported for transition metal complexes with carbo-and heterocyclic polyaromatic hydrocarbons (PAH) of small and medium size. Here, we report DFT studies of RuCp+ shifts between neighboring six-membered rings (eta(6) reversible arrow eta(6)-IRHR) on an extra-large PAH as a model for graphene and compare it to naphthalene. Our calculations predict that eta(6) reversible arrow eta(6)-IRHRs proceed with much lower activation energy barrier of rearrangement in the case of the RuCp+ complex of eta(6)-graphene model.

A series of heteroleptic cyclometallated 1,2,3-triazol-5-ylidene IrIII complexes were synthesized and structurally characterized. These new complexes demonstrated photoluminescence in green (550 nm) and cyan (499, 496 nm) regions. Their photophysical properties were rationalized using DFT calculations.

A series of novel (NHC)PdCl2-PR3 complexes were synthesized and fully characterized by 1H, 13C, 31P NMR and FT-IR spectroscopy. These complexes showed high catalytic activity toward solvent-free Buchwald-Hartwig amination. Both primary and secondary amines were efficiently utilized under the same reaction conditions. The solvent-free synthesis of valuable N-aryl carbazoles and similar N-heterocyclic systems was described.

International audience; The mechanism of inter-ring haptotropic rearrangements (IRHRs) was investigated by DFT for the tricarbonyl eta(6)-complexes of group 6 metals (M = Cr, Mo, W) of coronene (I-M), kekulene (II-M) and a model graphene (III-M). The computed eta(6),eta(6)-IRHR activation barriers in the middle size PAHs I-M and II-M were calculated to be substantially lower than those in the case of complexes of relatively small size PAHs such as naphthalene chromium tricarbonyl (Delta G approximate to 20-25 kcal mol(-1)vs. approximate to 30 kcal mol(-1)). The barrier is further lowered in the case of the model graphene complex III-Cr (Delta G approximate to 13 kcal mol(-1)). An even lower barrier is found for III-Mo (Delta G approximate to 10 kcal mol(-1)), whereas it slightly increases for III-W (Delta G approximate to 14 kcal mol(-1)).

We have investigated the role of ring sizes and substituents in NHC ligands in some (NHC)Au(I) complexes in the hydration of internal alkynes. Despite the fact that using (NHC)Au(I) complexes in the hydration of diarylacetylenes leads to Markovnikov-type products, the precise tuning of ligands allows changing the regioselectivity in arylalkylacetylene hydration to the anti-Markovnikov-type.

An efficient and practical method for a scalable synthesis of 3-arylbutadiene sulfones deals with the ligand-free Heck–Matsuda reaction of sulfolene with aryldiazonium tetrafluoroborates followed by triethylamine-promoted double bond shift.

Metalcyclopentadienyl complexes (MCp)

New high-performance catalytic systems based on Pd N-heterocyclic carbene complexes for the selective addition polymerization of 5-ethylidene-2-norbornene (ENB) were proposed. With these catalysts, polymerization can be conducted at unprecedentedly high monomer/catalyst ratio (up to 5 × 105/1) and gives high-molecular-weight soluble polymers with good film-forming properties. Varying the polymerization conditions (reaction temperature, monomer and catalyst concentrations, monomer/Pd ratio) makes it possible to prepare soluble ENB-based addition polymers with specified molecular weights in reasonable yields.

Ionic liquid/crown ether compositions are an attractive alternative to traditional extractants in the processes for spent nuclear fuel and liquid radioactive wastes reprocessing. These compositions are exposed to ionizing radiation, and their radiation stability, especially in the presence of metal salts, is a crucial issue. In the present study, the macrocyclic 18C6·Sr(BF4)2 and 18C6·Sr(PF6)2 complexes simulating the components of metal loaded ionic liquid/crown ether extractants were synthesized and their structures were characterized by FTIR spectroscopy and single-crystal X-ray diffraction analysis. Inclusion of Sr2+ cation into the 18C6 cavity resulted in more symmetric D3d conformations of the macrocycle. The structural transformations of the crown ether were accompanied by an elongation of polyether C—O bonds that could increase the possibility of radiolytic cleavage of the macrocycle. However, EPR study of the synthesized compounds subjected to X-ray irradiation revealed predominant formation of m...

Solvent-free protocols for palladium-catalyzed stannylation of aryl halides, Stille cross-coupling, and one-pot two-step stannylation/Stille cross-coupling (SSC) are reported for the first time. (Het)aryl halides bearing acceptor, donor, as well as sterically demanding substituents are stannylated and/or coupled in high yields. The reactions are catalyzed by conventional palladium(II) acetate/PCy3 (Pd(OAc)2/PCy3) under air, using available base CsF, and without the use of high purity reagents. The developed synthetic procedures are versatile, robust, and easily scalable. The absence of solvent, and the elimination of isolation procedures of aryl stannanes makes SSC protocol simple, step economical, and highly efficient for the synthesis of biaryls via one-pot two-step procedure.

A series of polymers of a new type, which contain rigid polymer main chains (glassy nature) and long flexible side substituents (rubbery nature), were prepared from norbornene derivatives with (AlkO)3Si-groups of a different length (Alk = Me, Et, n-Pr, n-Bu) as promising materials for membrane separation of gaseous hydrocarbons. The 1st generation Grubbs complex and Pd–N-heterocyclic carbene complex in combination with Na+[(3,5-(CF3)2C6H3)4B]− and PCy3 were used as catalysts of metathesis and addition polymerization in the synthesis of high-molecular weight polymers (Mw ≤ 1.1 × 106) with good or high yields (up to 99%). The prepared addition polymers were glassy, while the glass transition temperature of metathesis polymers depended on the length of the alkyl-group in (AlkO)3Si-substituents and it varied in the range of −44 to 61 °C. The dramatic tuning of polymer gas-transport properties was demonstrated by the change of the polymer main chain structure and the length of tri(n-alkoxy)silyl side groups. For example, we have succeeded for the first time in obtaining metathesis polynorbornenes, which turned out to be more permeable than their addition isomers. Not being large free volume polymers, all studied metathesis and addition polytricyclononenes exhibited solubility controlled permeation of hydrocarbons (P(n-C4H10) up to 8100 barrer) and high C4/C1 selectivity (22–49).

New norbornene type monomer bearing reactive triethoxysilyl group was synthesized, and its addition homo- and copolymerization with 3-trimethylsilyltricyclonon-7-ene was studied. The target monomer was obtained using regio- and stereospecific [2σ+2σ+2π] cyclo-addition of quadricyclane with vinyltrichlorosilane followed by the reaction of the formed cycloadduct with ethanol in the presence of triethylamine. Addition polymerization was investigated over the three-component Pd-containing catalytic system (Pd complex, Na+[B(3,5-(CF3)2C6H3)4]–(cocatalyst) and tricyclohexylphosphine). The N-heterocyclic carbene Pd complex (SIPrPd(cinn)Cl) with high activity and tolerance to the Si—O—C moieties was used as a catalyst. The yields of the homo- and copolymers were 24—68% depending on the monomer (comonomer): Pd: B: PCy3 ratio. The obtained addition polymers are high-molecular-weight amorphous products, the glass transition temperature of which exceeds 300 °C. The presence of reactive Si(OC2H5)3 groups in the homo- and copolymers made it possible to carry out a hard-to-realize cross-linking involving side substituents and followed by the formation of insoluble polymers.

An environmentally friendly and efficient synthesis of fully substituted 1,2,3-triazoles comprises solvent-free palladium-catalyzed Suzuki cross-coupling of halo-1,2,3-triazoles with pinacol arylboronates. The efficiencies of Stille and Suzuki reactions with halotriazoles under solvent-free conditions were compared.

General method of synthesis of 1,4-disubstituted-5-halo-1,2,3-triazoles have been developed. The one-pot two-step process consists of CuAAC of copper(I) acetylide with organic azide catalyzed by (aNHC)CuCl, and following halogenation using NCS, NBS or I2.

A general method of the synthesis of 1,4,5-trisubstituted-1,2,3-triazoles by Suzuki-Miyaura cross-coupling from 4- and 5-halo-1,2,3-triazoles is reported. The reaction is mediated by an expanded-ring N-heterocyclic carbene palladium complex in water. The developed reaction protocol meets the requirements of "green chemistry". Cross-coupling of 4- and 5-chlorotriazoles is reported for the first time.

Novel heteroleptic cyclometallated 1,2,3-triazol-5-ylidene IrIII complexes with 2-(5-trifluoromethyl-2H-1,2,4-triazol-3-yl)pyridine or 2-(1H-tetrazol-5-yl)pyridine as the ancillary ligands demonstrate photoluminescence in green (520 nm) and blue (450–480 nm) regions.

Although benzotriazoles are important and ubiquitous, currently there is only one conceptual approach to their synthesis: bridging the two ortho-amino groups with an electrophilic nitrogen atom. Herein, we disclose a new practical alternative – the endo-cyclization of 2-azidoaryl lithiums obtained in situ from 2-azido-aryl bromides. The scope of the reaction is illustrated using twenty-four examples with a variety of alkyl, alkoxy, perfluoroalkyl, and halogen substituents. We found that the directing effect of the azide group allows selective metal–halogen exchange in aryl azides containing several bromine atoms. Furthermore, (2-bromophenyl)diazomethane undergoes similar cyclization to give an indazole. Thus, cyclizations of aryl lithiums containing an ortho–X = Y = Z group emerge as a new general approach for the synthesis of aromatic heterocycles. DFT computations suggested that the observed endo-selectivity applies to the anionic cyclizations of other functionalities that undergo “1,1-additions” (i.e., azides, diazo compounds, and isonitriles). In contrast, cyclizations with the heteroatomic functionalities that follow the “1,2-addition” pattern (cyanates, thiocyanates, isocyanates, isothiocyanates, and nitriles) prefer the exo-cyclization path. Hence, such reactions expand the current understanding of stereoelectronic factors in anionic cyclizations.

A series of symmetric and nonsymmetric tetrahydroindenyl zirconium complexes was obtained by the reaction of ZrCl4 or (CpTMS)ZrCl3 with lithium salts of the corresponding tetrahydroindenes. Activated with methylalumoxane, these complexes exhibit high activity in polymerization of ethylene (up to 6.8∙106 g PE (mol Zr h)–1), as well as in copolymerization of ethylene and hex-1-ene (up to 8.6∙106 g PE (mol Zr h)–1).

A highly efficient solvent-free protocol for the Buchwald–Hartwig (hetero)arylation of anilines, diarylamines, and dialkylamines mediated by the expanded-ring N-heterocyclic carbene palladium complex (THP-Dipp)Pd(cinn)Cl [THP-Dipp = 1,3-bis(2,6-diisopropylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene; cinn = cinnamyl, 3-phenylallyl] was developed. The catalytic protocol was efficient for the coupling of amines and (hetero)aryl chlorides and bromides bearing donor, acceptor, and bulky substituents.

[(THD-Dipp)AuOTf], supported by the strongly electron donating, sterically bulky THD-Dipp (1,3-bis(2,6-diisopropylphenyl)hexahydro-2H-1,3-diazepine-2-ylidene) seven-membered N-heterocyclic carbene ligand, efficiently promotes intermolecular addition of Ts- and Boc-hydrazine to arylalkynes under solvent-free conditions.

Solvent-free protocols for Miyaura borylation and the one-pot, two-step homocoupling of aryl halides are reported for the first time. Bis(dibenzylideneacetone)palladium(0) [Pd(dba)2] is an optimal source of palladium for Miyaura borylation, while for one-pot two-step homocoupling palladium(II) acetate [Pd(OAc)2] gives highest yields. Aryl bromides are coupled most efficiently using the DPEphos ligand. Chlorides are coupled using XPhos. The developed protocols are robust, versatile and easily reproducible on a large scale.

Fischer's approach towards the synthesis of aryl azides and triazinoles from diazonium salts and hydroxylammonium chloride (phenylhydraxylamine) was reinvestigated and optimized. The new methodology enables the preparation of aryl azides and triazinoles in high yields in water at room temperature. The procedure is very simple, robust, easily scalable, reproducible, and “green”.

A highly efficient ‘green’ solvent-free monoarylation of primary anilines with aryl bromides mediated by the expanded-ring N-heterocyclic carbene palladium complex (THP-Dipp)Pd(cinn)Cl [THP-Dipp is 1,3-bis(2,6-diisopropylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene; cinn is cinnamyl] can be performed at low catalyst loadings (0.1 mol%) to provide excellent yields and remarkable selectivities for various substrates.

Herein four modified polymers were prepared from readily available addition poly(5-vinyl-2-norbornene) (PVNB) and their gas-transport properties were studied in detail. Hydrogenation, epoxidation, cyclopropanation and thiol-en reactions were chosen for the modifications of PVNB. Hydrogenation of PVNB was performed using p-toluenesulfonyl hydrazide. Epoxidation of PVNB was realized employing m-chloroperoxybenzoic acid. Cyclopropanation of PVNB was carried out using diazomethane in the presence of a Pd-catalyst. For thiol-en reaction, thioacetic acid was applied as the source of a thiol and AIBN as an initiator. All listed modifications were performed in high yields (≥80%) without the destruction of polymer main chains. The degree of functionalizations was up to 99%. The influence of these modifications on the properties of the resulting polymers was evaluated. Cyclopropanation and hydrogenation of PVNB led to an enhancement of gas permeability with minimal decrease in selectivity, while epoxidation or thioacetylation gave a substantial increase in CO2/N2 selectivity with decrease in permeability. The modified polymers with polar side-groups exhibited attractive selectivities for CO2/N2, CO2/CH4 and H2/N2 gas separations.

The synthesis and structural characterization of a series of novel platinum(0) complexes were reported. A number of (NHC)Pt(dvtms) (dvtms = 1,3-divinyl-1,1,3,3-tetramethyldisiloxane) complexes were investigated in catalytic addition of B2Pin2 to terminal alkenes. The novel expanded ring N-heterocyclic carbene complex (7-Dipp)Pt(dvtms) showed highest performance, turnover numbers up to 3800 were achieved. The scope of the reaction was illustrated by 20 examples with a variety of alkyl, alkoxy, halogen, ester, ketone and acetal substituents.

We have studied applicability of reversible addition-fragmentation chain transfer/macromolecular design via the interchange of xanthate (RAFT/MADIX) method to radical cyclopolymerization of protonated diallylammonium monomer, namely diallylammonium trifluoroacetate (DAATFA), occurring with efficient chain transfer to monomer reaction. The latter drives to a significant extent polymerization, noticeably setting molecular weight, MW, of polymers and their polydispersity (polydispersity index (PDI) = 2.8–3.0). For the first time, upon DAATFA polymerization in presence of RAFT ethylxanthogenacetic acid (xanthate) in aqueous solutions at 70 °C, the side chain transfer reaction was inhibited and control of the polydispersity was achieved, the PDI = 1.2–1.3. The structural characteristic of poly(diallylammonium trifluoroacetate) (PDAATFA) polymers was analyzed via 1H and 13C NMR and IFS FTIR (ATR) spectroscopy. It was proved that the structure of polymers obtained by RAFT polymerization fully corresponds to the polymers PDAATFA containing cationic pyrrolidinium links and trifluoroacetate-counterions. At the optimal xanthate concentrations, the main products are polymers with the end dithiocarbonate group, i.e. macro-RAFT PDAATFA. Static/dynamic light scattering, viscometry and ultracentrifugation were used for polymers characterization. Molecular weight was determined by two independent methods: static light scattering (Mw) and hydrodynamic parameters analysis (MDη). The PDI Mw/Mn was calculated on the basis of Fujita approach, using the determined distributions of sedimentation coefficients. The experimental number average molecular weights, Mn, grow with polymerization time, 6700 g mol−1

A general, economical, and environmentally friendly method of amide synthesis from phenyl esters and aryl amines was developed. This new method has significant advantages compared to previously reported palladium-catalyzed approaches. The reaction is performed transition metal- and solvent-free, using a cheap and environmentally benign base, NaH. This approach enabled us to obtain target amides in high yields with high atom economy.

New microporous homopolymers were readily prepared from norbornadiene-2,5, its dimer and trimer by addition (vinyl) polymerization of the corresponding monomers with 60&ndash, 98% yields. As a catalyst Pd-N-heterocyclic carbene complex or Ni(II) 2-ethylhexanoate activated with Na+[B(3,5-(CF3)2C6H3)4]&minus, or methylaluminoxane was used. The synthesized polynorbornenes are cross-linked and insoluble. They are glassy and amorphous polymers. Depending on the nature of the catalyst applied, BET surface areas were in the range of 420&ndash, 970 m2/g. The polymers with the highest surface area were obtained in the presence of Pd-catalysts from the trimer of norbornadiene-2,5. The total pore volume of the polymers varies from 0.39 to 0.79 cm3/g, while the true volume of micropores was 0.14&ndash, 0.16 cm3/g according to t-plot. These polymers gave CO2 uptake from 1.2 to 1.9 mmol/g at 273 K and 1 atm. The porous structure of new polymers was also studied by means of wide-angle X-ray diffraction and positron annihilation lifetime spectroscopy.

In this work we report the synthesis and polymerization of new norbornenes containing trialkoxysilyl groups. These monomers were reactive both in ROMP and in addition polymerization. Obtained polymers possessed interesting properties. So despite of low surface area they were good permeable, and some of them exhibited a low tendency to aging. The solubility controlled selectivity for hydrocarbons was observed. These properties would allow finding industrial application of obtained polymers for the membrane gas separation of hydrocarbon mixtures.