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Photo‐ and electrochemical properties of a novel cymantrenyl‐containing (CpMn(CO)3) phthalimide were studied by cyclic voltammetry, FTIR, 1H NMR, UV‐vis, fluorescence spectral methods. It was found that upon irradiation of the initial tricarbonyl complex, one CO ligand is released to form a colored dicarbonyl chelate, which in the presence of CO enters the reverse thermal reaction to give the initial tricarbonyl complex. In the presence of some other external ligands, the chelate cycle is disclosed and dicarbonyl complex with external ligand is formed demonstrating hemilabile properties of the chelate studied. It was found that the introduction of a cymantrenyl group in a phthalimide molecule, which usually exhibits electron acceptor properties, has a significant effect on the characteristics of the absorption and emission spectra, electrochemical properties. This type compounds can be a basis for the creation of photo‐ and electroactive materials and exciplex‐forming materials [ABSTRACT FROM AUTHOR]

• Study of photochemical behavior of di(cymantrenylalkyl)disulfide. • Preparation of stable bicyclic dicarbonyl chelates. • Preparation in situ of unstable fulvenes. • Study electrochemical properties of symmetrical disulfides. Photolysis of di(cymantrenylalkyl)disulfides was studied by IR, 1H NMR and UV-vis spectroscopy. Irradiation of cymantrenes with a disulfide bridge results in the formation of two type dicarbonyl chelates with Mn-S bond. The first type is formed due to removal of one CO ligand from one cymantrenyl moiety to give a 5-membered chelate cycle; the other is formed due to removal of two CO ligands from two cymantrenyl moieties to form a bicyclic chelate. The latter was isolated and characterized by X-ray analysis. For the first time, unstable fulvenes were prepared in situ by irradiation of cymantrenyl derivatives or their dicarbonyl complexes. Electrochemical properties of disulfides were studied before and after photolysis in acetonitrile. The manganese oxidation potential value increased on going from tricarbonyls to dicarbonyls. [Display omitted] [ABSTRACT FROM AUTHOR]

High-temperature polymer-electrolyte membrane fuel cells (HT-PEMFCs) are a very important type of fuel cells since they operate at 150–200 °C, making it possible to use hydrogen contaminated with CO. However, the need to improve the stability and other properties of gas-diffusion electrodes still impedes their distribution. Self-supporting anodes based on carbon nanofibers (CNF) are prepared using the electrospinning method from a polyacrylonitrile solution containing zirconium salt, followed by pyrolysis. After the deposition of Pt nanoparticles on the CNF surface, the composite anodes are obtained. A new self-phosphorylating polybenzimidazole of the 6F family is applied to the Pt/CNF surface to improve the triple-phase boundary, gas transport, and proton conductivity of the anode. This polymer coating ensures a continuous interface between the anode and proton-conducting membrane. The polymer is investigated using CO2 adsorption, TGA, DTA, FTIR, GPC, and gas permeability measurements. The anodes are studied using SEM, HAADF STEM, and CV. The operation of the membrane–electrode assembly in the H2/air HT-PEMFC shows that the application of the new PBI of the 6F family with good gas permeability as a coating for the CNF anodes results in an enhancement of HT-PEMFC performance, reaching 500 mW/cm2 at 1.3 A/cm2 (at 180 °C), compared with the previously studied PBI-O-PhT-P polymer. [ABSTRACT FROM AUTHOR]

Continuing our investigation of catalytic oxo/imido heterometathesis as novel water‐free method for C=N bond construction, we report here the application of classical transition metal oxides dispersed on silica (MOx/SiO2, M=V, Mo, W) as cheap, robust and readily available alternative to the catalysts prepared via Surface Organometallic Chemistry (SOMC). The oxide materials demonstrated activity in heterometathetical imidation of ketones, WO3/SiO2 being the most efficient. We also describe a new well‐defined supported W imido complex (≡SiO)W(=NMes)2(Me2Pyr) (Mes=2,4,6‐Me3C6H2, Me2Pyr=2,5‐dimethylpyrrolyl) and characterize it with SOMC protocols, which allowed us to identify the position of W on the oxo/imido heterometathesis activity scale (Mo

• Synthesis of new 3-cymantrenylalkylisothioureas. • Study of photochemical behavior of 3-cymantrenylalkylisothioureas. • Formation of photochromic system between tri- and dicarbonyl complexes. • Formation of photochromic pair between dicarbonyl chelates. A series of 3-cymantrenylalkylisothioureas (2) was synthesized. DFT calculations showed that compounds 2 in solutions are dimers. The photolysis of 2 was studied by IR, UV–vis and NMR spectroscopic methods. Irradiation of compounds 2 results in the formation of two type chelates, in which the manganese atom is coordinated to the S (3) or N (4) atoms of a substituent. The color of solutions sharply changes giving in the UV–vis spectra two new bands at 485 and 590 nm, respectively. In the presence of CO, dicarbonyl chelates enter the reverse thermal reaction to give the starting tricarbonyl complexes thus forming intermolecular photochromic systems. A quantum yield of the photolysis of 2a in benzene equals 0.63 ± 0.07. In the absence of СО, intramolecular linkage isomerization of 4 to 3 occurs. It was found that the bulkiness of a substituent at the sulfur atom insignificantly influences the reaction rate of the reverse thermal reaction. Chelate 3a was isolated; its photolysis gives orange chelate 4a , which isomerizes to violet chelate 3a forming an intramolecular photochromic pair. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Treatment of (2-methoxyprop-2-yl)diphenylphosphine oxide with alkyl bromides affords alkyl(diphenyl)phosphine oxides in good yields. [ABSTRACT FROM AUTHOR]

Sulfur‐containing cymantrene derivatives having one or two organometallic moieties were studied by NMR, IR, UV/Vis spectroscopic methods and CVA under irradiation conditions. Photolysis of compounds 1–3 leads to the formation of rare 4‐membered chelates 4, 5 and 8. In the presence of external ligand (L), dissociation of the Mn−S bond occurred to form new dicarbonyl complexes with the Mn−L bond, which demonstrates the hemilabile character of the chelates obtained. The results were confirmed by DFT calculations. CVA method showed manganese oxidation potential value increased in the case of dicarbonyls (1313 mV for 4) as compared to that of tricarbonyls (1067 mV for 1). [ABSTRACT FROM AUTHOR]

Photochemical properties of symmetrical pyromellitic diimide containing two cymantrenyl fragments at two nitrogen atoms were studied with IR, NMR, UV-vis, ESI-MS, and cyclic voltammetry. It was found that new unstable chelates are formed during photolysis. At the same time, the CO ligand dissociates from two Mn(CO)3 fragments during photoexcitation, which dramatically changes the electronic and redox properties of the molecule compared to the cymantrene derivative containing one imide fragment. Photolysis leads to a color change from light yellow to green. DFT calculations confirmed the possibility of the formation of complexes due to the loss of one or two CO ligands from manganese atoms. The results obtained with variation of photolysis conditions demonstrated the hemilabile character of the Mn-O=C(imide) bond. On addition of external ligands, the color and electrochemical properties changed, which is promising for the use of this complex as a sensor for small molecules. [ABSTRACT FROM AUTHOR]

Isomeric 4,5‐dihydro‐2‐[(cymantrenylmethyl)thio]thiazole (1) and 3‐(cymantrenylmethyl)‐1,3‐thioazolidine‐2‐thione (2) were synthesized and photochemical behavior and spectral characteristics of tricarbonyl and dicarbonyl complexes were studied. Irradiation of compounds 1 and 2 results in the formation of stable chelates due to coordination of manganese to the donor nitrogen and sulfur atoms of the thiazolidine substituent. Photolysis is accompanied with a colour change and the corresponding changes in the UV/Vis spectra depending on the solvent used. In the presence of CO, the dicarbonyl chelates enter the dark reaction to give the parent tricarbonyl complexes thus forming intermolecular photochromic systems. Photolysis of the dicarbonyl chelate 5 gives the isomeric chelate 6, which in the course of the dark isomerization transforms into complex 5. Chelates 5 and 6 form an intramolecular photochromic pair. An intramolecular photochromic pair including N‐ and S‐coordinated chelates of thiazolidine derivatives of cymantrene is for the first time reported. The reverse reaction occurs via SN1 mechanism with a half‐conversion time for the dark isomerization being 160 min. The quantum yield for the photolysis at λ 366 nm is 0.99. [ABSTRACT FROM AUTHOR]

1N- and 2N-cymantrenylalkylsubstituted 1,2,3-triazoles were for the first time synthesized. It was found that irradiation by a mercury lamp light with λ = 365 nm of cymantrenylalkyl-1,2,3-triazoles 3, 5 – 8 gives stable dicarbonyl chelates 4, 9 – 12 . In a closed system without CO removal, intermolecular photochromic systems between tricarbonyl and dicarbonyl complexes were formed; half-conversion time for the dark reaction was more than 10 h. The effect of a substituent position in dicarbonyl chelates 4, 9 – 12 on the parameters of their spectra, coordination ability of the N atom and chemical stability was studied. It was found that coordination ability of the nitrogen atoms markedly depends on steric hindrances, which are significantly different in 1N- and 2N-substituted triazoles. [ABSTRACT FROM AUTHOR]

Cyclopentadienyl manganese tricarbonyl (cymantrene) is known to undergo photochemical reactions by releasing one of its CO ligands. Here we present the first example of a photorearrangement of a cymantrenylmethyl fragment, where it retains all its three CO ligands. A tandem experimental and DFT (density functional theory)-based computational investigation allows us to explain this unexpected behavior: the rearrangement, indeed, begins with the release of one CO ligand, but cage effect of the solvent captures this CO molecule, allowing it to rapidly reattach once the rearrangement takes place. [ABSTRACT FROM AUTHOR]

For the first time, the photochemical properties of compounds 1–4 containing a cymantrene fragment at the 2‐ or 3‐position of the quinazolinone have been studied. It was found that the ‐NC=O group in compounds 1 and 2 is capable of coordinating to the Mn atom with the formation of intramolecular chelates. The influence of the nature of the solvent and substituent in the side‐chain of cymantrene on the thermodynamic and kinetic stability of the dicarbonyl complexes was studied. For the first time, the olefin chelate 9 was isolated; its structure was established by X‐ray diffraction analysis and its photochemical and fluorescence properties were studied. The photolysis of compound 4 gave only stable intermolecular dicarbonyl complexes, in which the solvent can be easily replaced by n‐ and π‐donor ligands. [ABSTRACT FROM AUTHOR]

The synthesis of four new 1,2,3-triazole derivatives and seven 1,2,3-triazolium salts that contain an organometallic group (i.e., cymantrenyl and ferrocenyl) at either the N-1, N-2, or N-3 position was realized. The alkylation of organometallic and organic triazole derivatives was investigated, and as a result of these studies, it was found that the presence of a good leaving group at the heterocyclic nitrogen atom led to transalkylation and subsequent migration of the N-1 substituent to the N-2 position of the triazole moiety. The nucleophilicity of the counterion of the triazolium salt influenced the transalkylation and isomerization processes, which suggests that the elimination of the N-substituent most likely occurs though a concerted mechanism with nucleophilic assistance from the counterion. Thus, a new approach to the synthesis of 2,4-disubstituted 1,2,3-triazoles has been developed. [ABSTRACT FROM AUTHOR]

A new and efficient method for the synthesis of 6-amino-2,3-dihydro-4-pyridinethiones from N -(3-butenyl)thioureas, without the use of conventional thiophosphorus reagents has been reported. Thioureas are initially transformed into iodocyclothiocarbamates which subsequently give cyclic thioenol esters after base-mediated HI elimination. These esters readily undergo a base-mediated ( t BuOK) thioenolate-carbodiimide rearrangement, accompanied by C S bond cleavage and C C bond formation, to finally give a series of novel 6-amino-2,3-dihydropyridine-4-thiones. [ABSTRACT FROM AUTHOR]

We report here the synthesis of 4‐coordinate Ti imido complexes Ti(=NtBu)(OArtBu)2(py) (2) and Ti(=NtBu)(OArtBu)(Me2Pyr)(py) (3) (ArtBu=O‐2,6‐tBu2‐4‐MeC6H2, Me2Pyr=2,5‐dimethylpyrrolyl) and study their grafting onto the surface of partially dehydroxylated silica with the aim to prepare 4‐coordinate Ti imido aryloxide surface species. Study of the resulting materials with IR, solid‐state NMR, elemental and mass balance analyses demonstrates that grafting of bis‐aryloxide complex 2 leads to a predominant formation of silica‐supported Ti amide (≡SiO)Ti(NHtBu)(OArtBu)2(py) resulting from the protonation of the imido ligand with the surface silanols and only a smaller fraction of the desired imido species (≡SiO)Ti(=NtBu)(OArtBu)(py). The use of the tailored complex 3 where one of the aryloxides is replaced with a more reactive pyrrolyl ligand significantly increases the selectivity of grafting leading to the formation of the Ti imido aryloxide (≡SiO)Ti(=NtBu)(OArtBu)(py) as major surface species. The obtained materials show high activity in catalytic oxo/imido heterometathesis supporting the previously proposed hypothesis that electron‐donating environments are favorable for this transformation. [ABSTRACT FROM AUTHOR]

Abstract: The In and Zn-mediated allylation of substituted pyrazol-4-yl derived (R)-N-tert-butanesulfinyl imines proceeds with high diastereoselectivity depending on the conditions and additives (up to 99.4% de). Thus, the synthesized diastereomeric homoallylsulfinamides were isolated and characterized as pure diastereomers, which were then converted into the corresponding pyrazol-4-yl-derived N-Boc-homoallylamines via consecutive treatment with HCl and Boc2O. The latter were then subjected to a sequence of reactions: cyclobromocarbamation with NBS and enolate–isocyanate rearrangement with tBuOK to give novel enantiomerically pure (S)-6-(pyrazol-4-yl)-piperidine-2,4-diones in 88–96% yield. The absolute configurations of the allylation products were assigned by X-ray single crystal analysis of the intermediate bromomethylurethanes. [Copyright &y& Elsevier]

We report the first examples of direct imidation of lactones giving the corresponding cyclic imidates via oxo/imido heterometathesis with N-sulfinylamines catalysed by a well-defined silica-supported Ti imido complex. [ABSTRACT FROM AUTHOR]

A series of N,N'-dialkylated derivatives of (1R,2R)-cyclohexane-1,2-diamine were synthesized, and a new approach to the one-pot preparation of this type of amine was demonstrated. The prepared diamines were used as organocatalysts for the two-step synthesis of α-hydroxy γ-keto esters from arenes, chlorooxoacetates, and ketones; they were also used as chiral ligands for Meervein-Ponndorf-Verley reductions and Henry reactions. [ABSTRACT FROM AUTHOR]

Four monosubstituted cymantrene derivatives ( 5- 8) containing two functional groups (allyl and amide) in a dendritic substituent were synthesized. The irradiation of these compounds with an Hg lamp in solution and under solvent-free conditions gives two types of dicarbonyl chelates with Mn-olefin or Mn-amide coordination bonds. Olefin chelates ( 19 and 21) were isolated for the first time, and they undergo reverse photochemical intramolecular isomerization to the amide chelates in solution and as pure liquids. For the first time, it was shown that the photochromism of cymantrene functional derivatives can be observed without the use of a solvent. [ABSTRACT FROM AUTHOR]

Metallacarborane [1,8-Me2-2,2-(C 2 H 4 )2-7-SMe2-2,1,8-IrC 2 B 9 H 8 ] (1) was obtained by an interaction of [(C 2 H 4 )2IrCl] 2 with Tl[9-SMe 2 -7,8-Me2-7,8-C 2 B 9 H 8 ]. Reaction proceeds with a low temperature “1,2 → 1,7” polyhedral rearrangement. Ethene complex 1 reacts with iodine in toluene with the formation of ionic compound 3, consisting of cationic [(1,8-Me2-7-SMe2-2,1,8-IrC 2 B 9 H 8 )2I 3 ]+ (3a+) and anionic [(1,8-Me 2 -7-SMe-2,1,8-IrC 2 B 9 H 8 )2I 3 ]− (3b–) iodide species. The structures of 1 and 3 were determined by X-ray diffraction. [ABSTRACT FROM AUTHOR]

Chemical equations for the article "Diastereoselective In and Zn-Mediated Allylation of Pyrazol-4-yl Derived (R)-tert-Butanesulfinyl Imines: Synthesis of Enantiomerically Pure 6-(Pyrazol-4-yl)-piperidin-2,4-diones" by Y.N. Bubnov et al. in the journal "Tetrahedron: Asymmetry" in 2014 are presented.

Two manganese-containing catalysts have been employed in the oxidation with hydrogen peroxide of two reactive alcohols (1-phenylethanol and glycerol): soluble catalyst [LMn(μ-O)MnL](PF) ( 1a) and heterogenized catalyst [LMn(μ-O)MnL][SiWO] ( 1b) (L is 1,4,7-trimethyl-1,4,7-triazacyclononane, TMTACN). Oxidation of 1-phenylethanol catalyzed by 1a in acetonitrile solution proceeds at room temperature in the presence of a small amount of oxalic acid; the turnover number attains 15,000 after 3 h. It has been proposed on the basis of the kinetic study that an oxidizing species is a manganyl species containing fragment “Mn=O” rather that hydroxyl radical. This species reacts competitively with the alcohol, acetonitrile and hydrogen peroxide. In the case of 1b dependences of the initial rates of acetophenone accumulation on concentration of the alcohol and amount of 1b have plateau. Both homogeneous and heterogeneous catalysts are efficient in the oxidation of glycerol to produce dihydroxyacetone (DHA) as the main product. The oxidation catalyzed by 1a is one of the first examples of the glycerol oxidation by a catalytic homogeneous system. The yield of valuable products attained 45%. The oxidation of DHA in the absence of glycerol afforded mainly glycolic acid in yield 60% based on the starting DHA. The oxidation on 1b represents the first example of the glycerol transformation catalyzed by a heterogenized metal complex. Under certain conditions yields of products of deeper oxidation (glyceric, glycolic and hydroxypyruvic acids) are somewhat higher than the yield of dihydroxyacetone. Special experiments demonstrated that no leaching of active species occurs from catalyst 1b to the solution and that this catalyst can be re-used at least four times without substantial loss of activity. Graphical Abstract: Manganese-containing complexes are very efficient catalysts in the oxidation of reactive alcohols (1-phenylethanol and glycerol) with HO: soluble [LMn(O)MnL](PF) and heterogenized [LMn(O)MnL][SiWO] (L is 1,4,7-trimethyl-1,4,7-triazacyclononane). [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: The bis(maltolato)oxo complexes of vanadium(V) and vanadium(IV) both in a soluble form and anchored to chemically modified silica gel, when used in combination with pyrazine-2-carboxylic acid (PCA), catalyze the oxidation of benzene to phenol and alkanes to the corresponding alkyl hydroperoxides with H2O2 at 40–50°C. Heterogenizing the complexes leads to changes in regioselectivity and bond selectivity parameters of the alkane oxidation, and this opens new routes to the enhancement of the selectivity in oxidation processes. [Copyright &y& Elsevier]

Polycondensation of four stereoisomers of (tetrahydroxy)(tetraphenyl)cyclotetrasiloxane in solution in the presence of layeredarchitecture compounds afforded polyphenylsilsesquioxanes with different conformational and configurational structures of the siloxane framework, determined by IR, 29 Si NMR spectroscopy, powder X-ray diffraction and MALDI analysis. [ABSTRACT FROM AUTHOR]

Oligo- and polycyclosiloxanes were obtained by the polycondensation of (tetrahydroxy)(tetraaryl)cyclotetrasiloxanes in equilibrium and non-equilibrium conditions in the presence and absence of montmorillonite (MMT). Their composition and the structures of their components were investigated by infrared (IR) spectroscopy, 29Si nuclear magnetic resonance (NMR) spectroscopy, atmospheric pressure chemical ionization (APCI) mass spectrometry, powder X-ray diffraction (XRD), and gel-penetrating chromatography (GPC). Also, a comparison of polymers formed in the presence of MMT and via anionic polymerization was performed showing differences in their structures. [ABSTRACT FROM AUTHOR]