The bis(carbazolide) complex of Smii, Sm[3,6-But2-1,8-(Me3SiC degrees C)2Carb]2, was synthesized by the transamination reaction of Sm[N(SiMe3)2]2(THF)2with two molar equivalents of carbazole 3,6-But2-1,8-(Me3SiC degrees C)2CarbH. A similar reaction of the less sterically demanding carbazole 3,6-But2-1,8-(PhC degrees C)2CarbH is accompanied by the oxidation of Smii to Smiii and lead to the formation of bis(carbazolide) amido complex [3,6-But2-1,8-(PhC degrees C)2Carb]2Sm[N(SiMe3)2]. For both Sm complexes, hhh2-interactions with C degrees C bonds, which are unconventional for Lnii and Lniii metals, were experimentally confirmed by single-crystal X-ray diffraction, IR and Raman spectroscopy along with QTAIM analysis.

Micro-Raman spectroscopy of Luna-16 and Luna-24 regolith samples revealed 27 unshocked components, including first-time detections of metallic silicon and arzakite. The study identified sp2-carbon formations (500-1000 degrees C) and proposed a spectral criterion to determine carbon origin (impact, meteoritic, or micrometeoritic). Carbon in Mare Crisium and Fecunditatis regolith was classified as micrometeoritic. Lower carbon content in Luna-24 (2 m depth) suggests increased micrometeoritic bombardment of carbonaceous chondrites in recent time.

On the basis ofp-diacetylbenzene and 4,4'-diacetylbi phenyl, polyphenylenepyridines with a ratio of pyridine to phenylene rings of 1 : 5-6.5 were synthesized. Their heating in argon at 450, 800 and 1000 degrees C afforded porous polymers with a specific surface area up to 1146 m2 g-1. X-ray photoelectron spectroscopy of these substances showed that nitrogen atoms in them exist mainly in the form of graphite-and pyridine-like systems. Intensity (arbitrary units) 2 1 0 406 404 402 400 398 396 Binding energy/eV N N N N

The significance of the development of porous organic polymers (POPs) is broadly acknowledged in both academia and industrial communities. Advances in POP synthesis have paved the way for modern technologies in gas separation and storage, photovoltaics, and catalysis. In catalysis, POPs are ideal candidates for the heterogenization of highly active catalytic metal species due to their unique surface porous properties. The design of inexpensive, highly active, and reusable heterogeneous catalysts via robust synthetic techniques is of particular importance in the case of industrial applications in the conversion of biomass-derived platform molecules into value-added chemicals. We present an elegant approach for embedding Ni nanoparticles within a microporous aromatic pyridyl-containing polymer framework to create a heterogeneous catalyst for the hydrogenation of furfural to furfuryl alcohol. This process involves the cyclotrimerization of a dendritic aromatic multifunctional ethynyl-terminated monomer, catalyzed by nickel(II) bis(acetylacetonate). Subsequently, the material is subjected to thermal treatment at 500 degrees C in an Ar/H2 atmosphere, facilitating the reduction of Ni2+ to Ni0, as confirmed by XPS analysis. This method enables the simultaneous encapsulation of Ni and the formation of the POP framework with a specific surface area of up to 918 m2/g and a high micropore content of up to 81%. The reaction conditions were effectively adjusted to alter the porous properties. The catalytic composites demonstrate exceptional activity in the selective hydrogenation of furfural to furfuryl alcohol, achieving selectivity exceeding 99% even with a minimal nickel loading of 0.06 mol %. The presence of pyridyl units in the polymer support, along with high microporosity, enhances both the activity and selectivity of the resulting porous catalytic composites in the hydrogenation of furfural. The catalysts were successfully reused five times without loss of activity. Comprehensive characterization of the catalysts highlighted the significant influence of the porous polymer carrier on the efficiency of hydrogenation and emphasized the role of nitrogen species in catalyst stability.

In this work, an approach enabling the synthesis of η2-alkene lithium complexes (Carb2,4,6-iPr)Li(η2-L) (L = 1-octene, cyclohexene) is elaborated. For 1,5-hexadiene, the same approach results in a binuclear μ-η2:η2-diene complex. The QTAIM parameters reveal the electrostatic nature of the Li-alkene interaction. When treated with cyclohexane, alkene ligands in (Carb2,4,6-iPr)Li(η2-L) are readily replaced to afford the Li-alkane complex (Carb2,4,6-iPr)Li(κ2-C6H12) featuring anagostic Li···H interactions. The reverse reaction readily proceeds in the presence of excess alkene. The QTAIM and LED analyses performed at the DLPNO-CCSD(T) level show a small difference between the complexes in the total dispersion contribution (16.0-18.5 kcal/mol) and interaction energy for Li-alkene (∼3.5 kcal/mol) or Li-C6H12 (∼4 kcal/mol). These values suggest the presence of an equilibrium between these entities, which can be readily shifted by the presence of an excess of alkene or alkane. (Carb2,4,6-iPr)Li(η2-L) and (Carb2,4,6-iPr)Li(κ2-C6H12) are transformed into η2-arene complexes upon treatment with benzene; however, a reverse reaction is not possible at room temperature.

6-[2-(1H-Imidazol-4-yl)ethylamino]-5-oxopentanoic acid (IPA) is a nontoxic broad-spectrum antiviral drug approved in Russia for treatment and prophylaxis of seasonal influenza and other acute respiratory viral infections. Although it has been used since 2007, data about its crystal structure(s) are still missing. Herein, we report on crystal structures; thermal analysis; N-15 and C-13 NMR, FTIR, and Raman spectra; and DFT studies of two forms of IPA. Vibrational spectra also revealed the presence of additional forms in solids. Structural analysis demonstrated similarity of molecular structures and H-bonded dimers in forms I and II and allowed us to suggest possible relations between an H-bonded framework and layers observed in these forms. DFT studies indicate that form II is 0.84 kJ/mol more stable than form I. Pressure-dependent FTIR study revealed the irreversible transition of polymorph II into I at 28 GPa.

Bis(carbazolide) complexes M[3,6-tBu(2)-1,8-(RC equivalent to C)(2)Carb](2)(THF)(n) (R=SiMe3, n=0, M=Ca, Yb; R=Ph, n=1, M=Ca, Yb; n=0, M=Yb) were synthesized through transamination reaction of M[N(SiMe3)(2)](2)(THF)(2) with two molar equivalents of carbazoles. The complexes feature M(eta(2)-C equivalent to C)(4) structural motif composed of M(II) ions encapsulated by four acetylene fragments due to atypical for alkaline- and rare-earth metals eta(2)-interactions with triple C equivalent to C bond. This interaction is evidenced experimentally by X-ray diffraction, Raman spectroscopy in the solid state and by NMR-spectroscopy in the solution. According to QTAIM analysis there are 4 bond critical points (3;-1) between the metal atom and each of the triple bonds, which are connected by a strongly curved, almost T-shaped bond pathway.

Polyacrylonitrile and polyheteroarylenes, such as polybenzimidazole (PBI) and a polymer of intrinsic microporosity (PIM-1), have been employed to prepare nanoporous electrospun carbon nanofiber (CNF)-based materials for high-temperature proton-exchange (or polymer-electrolyte) membrane (HT-PEM) fuel cells. The nanoporous CNF mats are obtained by Nanospider (needle-free) electrospinning method from polymer solution followed by pyrolysis at 1500 degrees C to form nanoporous electrospun polymer nanofiber self-supporting mats with micropores (D < 2 nm) and mesopores (D 2-50 nm). The nanoporous CNF samples are extensively characterized by N-2 and CO2 adsorption applying the BET, BJH, Dubinin-Radushkevich (DR), NLDFT, and GCMC methods, CO2 uptake, Raman spectroscopy, elemental analysis, electrical conductivity, electron microscopy, and XPS. The role of the polymer precursor on the obtained values of specific surface area (SSA) and volume for micro- and mesopores is presented and discussed. The PBI-based CNF material reaches a micropore SSA of 919 m(2) g(-1) and CO2 uptake of 4.0 mmol g(-1) derived from CO2 adsorption (273 K) data, and a micropore SSA of 873 m(2) g(-1) according to the t-method derived from N-2 adsorption data. Close values confirm higher accessibility of micropores compared with the case of PIM-based CNF, where the micropore SSA values derived from CO2 and N-2 adsorption data are different and indicate the partial inaccessibility of micropores for low-temperature nitrogen adsorption (77 K). Platinum-decorated CNF mats are successfully tested as electrodes for HT-PEM fuel cells, showing the feasibility of using the mats as cathodes; nevertheless, further optimization is required. For CNF anodes, the HT-PEM fuel cell performance reaches 0.69 V at 0.2 A cm(-2) and 0.53 W cm(-2) at 1.4 A cm(-2) which permits the use of the Pt/CNF mats as anodes.

Raman spectroscopy was used to study the composition of contact masses (CMs) CuCl + Si obtained by different methods, which are utilized in the direct synthesis of alkoxysilanes. The CMs prepared by the classical method were shown to include copper oxides in a mixture with silicon and on the surface of metallic copper and Cu5Si intermetallide. Along with copper oxides, an active phase containing terminal Cu–Cl groups was also observed. In the case of mechanochemical synthesis, the formation of copper oxides was not observed. In view of the metallic conductivity of Cu3Si and Cu5Si, their direct identification using Raman spectra is not possible. All the mentioned copper-containing phases are involved in the reaction with alcohols and esters as catalysts. A difference between the two methods for obtaining CMs comes down to the presence or absence of a "catalytic cocktail", which significantly affects the parameters of the direct synthesis course.

It has been found using Raman spectroscopy that metastable Si phases reversibly appear in silicon microparticles (µ-Si) due to local heating on increasing the power of a He–Ne excitation laser from 0.03 to 3 mW. Prolonged annealing of these phases by laser radiation makes it possible to estimate that local heating occurs to a temperature of ∼250 °C rather than 1000 °C as it was believed previously.

Aromaticity as one of the most important fundamental concepts in chemistry is an effect of cyclic electron delocalization, which is very multifaceted and difficult to measure. To define the aromaticity degree as a quantitative characteristic, the aromaticity indices are used that can be divided into energetic, structural, electronic, magnetic, and optical. The aromaticity effect went far beyond the class of π-conjugated hydrocarbons a long time ago; therefore, this review critically examines the most important and modern criteria of aromaticity which are universal in the system choice and have been applied to organometallic compounds.

This paper submits experimental results of a study directed towards the formation of Eu ions’ luminescent centers in CVD diamond films. A new approach is based on use of diamond nanoparticles with a surface modified with Eu ions for seeding at CVD growth. Nanocrystalline diamond films (NCD) doped with Eu have been grown from the gas phase on silicon substrates by microwave plasma-assisted CVD at a frequency of 2.45 GHz. The photoluminescence spectra clearly show several electronic transitions of the Eu3+ ions, which confirm the incorporation of Eu ions into the NCD film.

Using the recent aromatic criteria, the conjugation and aromatic properties of group 4 metallacyclocumulenes Cp2M-eta(4)-(R)C=C=C=C-R (1) and Cp2M-eta(3)(R-C= C=C=C(R)-R(C)=CR) (2) (M = Ti, Zr, Hf) were studied. To these nontrivial bonded metallacycles, the most recent universal criteria of aromaticity were applied that do not require any parametrisation such as isomerisation stabilization energy, electron density of delocalized bonds (EDDB), nuclear independent chemical shift, and gauge-included magnetically induced currents (GIMIC). All methods used indicated the absence of the common p-type aromaticity. The most efficient EDDB and GIMIC methods showed in-plane aromatic pathway in 5-membered cycle 1 against 7-membered 2. The distribution of the induced currents (ICs) for such unique aromaticity type was demonstrated. It shows that the diatropic ICs of 1 are located both inside and outside the cycle. The population analysis of molecular orbitals and natural orbitals for delocalized bonds revealed the abidance to the 4n + 2 electron rule. According to EDDB and GIMIC data, the degree of aromaticity for 1 tends to decrease from Ti to Zr and Hf.

The first [4]radialene complex of zirconocene 1Zr-Ph was obtained by the reaction of Negishi’s reagent with 1,4-diphenylbutadiyne. The structure of 1Zr-Ph has been determined by X-ray diffraction. In addition, organometallic [4]radialenes of group 4 metallocenes were also studied with Raman spectroscopy and density functional theory calculations. The theoretical study illustrates the thermodynamic stability, electronic structure, and conjugation/aromaticity of organometallic radialenes with Ti, Zr, Hf, and various substituents.

The aromaticity in 2,3-pyrido-annulated 1,3,2λ2-diazatetroles C5H3N(NR)2EII (EII = C, Si, Ge, Sn, Pb) was studied using a set of experimental and calculated criteria: UV-VIS, Raman, ISE, NICS, GIMIC and EDDB. The data obtained indicate either a slight decrease in aromaticity (NICS, GIMIC, ISE methods) or equal aromaticity (UV-VIS, ISE methods) compared to benzo-annulated analogues C6H4(NR)2E. The π-aromaticity increases down the group from Si to Pb.

The vibrational spectra (IR and Raman) for seven-membered zirconacyclocumulenes of the type Cp2Zr[eta(3)-(RC)-C-1=C=C=C(R-1)-C(R-3)=CR2], R-1 = SiMe3, Bu-t, R-2 ,R-3 =Ph, SiMe3, Bu-t, -C C-SiMe3 -C C-Bu-t] were ob tained and studied using normal coordinate analysis. For metallacycles of this type, three lines are pronounced: 1870 and 1650 cm(-1) bands corresponding to symmetric (nu(1)) and antisymmetric (nu(2)) vibrations of cumulene fragment, as well as at similar to 1400 cm(-1) the nu C=C vibration, respectively. These data are consistent with the geometric parameters of the cycles and the results of QTAIM analysis, within which the molecular graph demonstrated three Zr-C bond paths. For a crystalline sample of the Cp2Zr[eta(3)-Me3SiC4(SiMe3)-C(Ph)=CPh] complex (2Zr(e)), irreversible isomerization under the action of a He-Ne laser into the cyclopentadiene structure Cp2Zr[eta(2)-(Me3SiC C)C=C(SiMe3)-C(Ph)=CPh] with a pendant alkyne substituent. Based on the IR spectra data for the Cp2Zr[eta(3)-Me3SiC4(SiMe3)-C(SiMe3)=C--C C-SiMe3] (2Zr(d)) complex, the preservation of the cyclocumulene structure in the dynamic process of its isomerization was proved. (C) 2021 Elsevier B.V. All rights reserved.

Three dimensional aromaticity in pyramidanes C4(SiMe3)4E (E = Ge, Sn, Pb, P+, BCl, Mg) and Ge4(SiMe3)4Ge was investigated using gauge-included magnetically induced currents and electron density of delocalized bonds as two criteria. For the C4(SiMe3)4E compounds, different series of the aromaticity degree have been obtained by the two methods, respectively: P > Ge ≥ Sn ∼ Pb > B and Pb ≥ Sn ≥ Ge > B > P. Two isomers of Ge4(SiMe3)4Ge possess nearly equal aromaticity.

Three series of N-heterocyclic carbene analogues including Arduengo-type systems (HCNBut)2E (1; E = C, Si, Ge, Sn), their benzannulated derivatives C6H4(NCH2But)2E (2; E = C, Si, Ge, Sn, Pb), and amidophenolates C6H2But2(O)NButE (3; E = Ge, Sn, Pb) were studied by the electron density of delocalized bonds (EDDB) method. The results obtained confirmed the π-aromaticity of systems 1–3. The aromaticity series were obtained. The degree of aromaticity of heavy carbene analogues increases on going down Group 14 of the periodic system.

The electronic structure and the conjugation in allyltetrylenes Ar-E-eta(3)-C3H4 (E= Si, Ge, Sn, Pb; Ar = C(6)H(3)Trip(2) (1), Ph (1')), which exhibit the unique symmetric eta(3)-coordination among the allyl compounds of the main groups, were studied by the DFT based methods. The QTAIM molecular graph exhibits two metal-allyl bond paths, which form 4-membered metallacycles. The advance aromaticity criteria NICS-scan, electron density of delocalized bonds (EDDB) and gauge-including magnetically induced currents (GIMIC) were firstly applied to the 1. The method results demonstrate a strong cyclic delocalization for organometallics. According to the NICS and GIMIC values, the aromaticity degree diminishes in the series Si similar to Ge > Sn > Pb. According to the EDDB results, it increases in the series Si < Ge < Sn < Pb from 38 % to 65%. The CMG and NODE population analyses reveal the unprecedented type of aromaticity, namely the four electron in-plane Mobius type. (C) 2021 Elsevier B.V. All rights reserved.