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This work discloses a zwitterionic approach for selective copolymerization of carbon dioxide (CO₂) and propylene oxide (PO), producing poly(propylene carbonate) (PPC), a biodegradable polymer with broad applications. Small-molecule catalysts composed of triethylamine (TEA) and trialkyl boranes are effective for CO₂/PO copolymerization with an alternating degree of >99% and a productivity of 171 g PPC/g catalyst. A diamine N,N,N′,N′-tetraethyl ethylenediamine (TEED) paired with trialkyl borane exhibited improved activity and productivity (up to 216 g PPC/g catalyst). By adjusting the Lewis acid–base pair, the PPC selectivity can be regulated to 99%. In addition, PPCs have medium regioregularity with a head-to-tail diad content of 80–82% and number-average molecular weights of up to 56.0 kg/mol with narrow polydispersity (below 1.2). The overall catalytic performance of these readily available simple molecules is better than that of previously reported organic catalysts for CO₂/PO copolymerization. Successive insertion of PO and CO₂ into the Lewis pair leads to the formation of an end-to-end zwitterion featuring a TEB-masked anion and an onium cation, which is highly selective to the alternating copolymerization, as demonstrated by quantum mechanical calculations.

In the present paper, we report a comprehensive theoretical evaluation of a hypothetical compound, hexazinane (cyclo-H6N6), and its 10 onium salts as high-energy density materials. Crystal structure prediction, which included dynamical and mechanical stability criteria estimation, found a P21/c space group crystal structure to be the lowest energy polymorph. Prediction of the chemical reactivity parameters of a hexazinane molecule revealed a strong basic character comparable with those of secondary and tertiary aliphatic amines. The onium salts of hexazinane with the carbon-free inorganic anions (NxOy)− and with several low carbon content organic anions demonstrate excellent detonation characteristics. Hexazinanium nitrate H7N6+NO3− has detonation performance comparable with e-CL-20, the most powerful non-nuclear explosive known. The corresponding salts with dinitramide N(NO2)2− and nitrite NO2− anions have only slightly lower characteristics more powerful than all known explosives, except for e-CL-20 and octanitrocubane. The reported “green” energetic materials also demonstrate excellent propulsive performance, and, if synthesized, these may find potential applications as solid rocket propellants.

In this article, the authors presented a literature search devoted to the isolation of onium type derivatives with a stereogenic sulfur atom and the determination of their chemical and optical stab...

Compared to currently studied metal-based catalysts, metal-free heteroatom-doped carbon catalysts have many advantages including no issues of degradation and contamination from metal dissolution. Relying on single type of doping usually cannot yield optimal electronic and geometric structures favorable for the oxygen reduction reaction (ORR). Herein, heteroatom N, P, and S simultaneously doped graphene-like carbon (NPS-G) was successfully synthesized from onium salts by a facile one-step pyrolysis method. The resulting metal-free NPS-G catalyst with optimized N, P, and S contents exhibits enhanced catalytic activity towards the ORR in alkaline media, relative to any single doping. In particular, this metal-free catalyst shows an encouraging half-wave potential (E1/2 = 0.857 V) comparable to that of metal-based catalysts. It also demonstrates excellent electrochemical stability and methanol tolerance. This catalyst was further studied as a cathode in a primary Zn-air battery, showing exceptional open-circuit voltage (1.372 V) and power density (0.151 W cm−2). The NPS-G cathode delivers a specific capacity of 686 mA h gZn-1 at a current density of 10 mA cm−2 while utilizing 82.2% of the theoretical capacity (835 mA h gZn-1). The origin of high activity associated with various heteroatom dopings is elucidated through X-ray photoelectron spectroscopy analysis and density functional theory studies. The enhanced chemisorption of oxygen species (*OOH, *O and *OH) onto the dopants of the NPS-G catalysts reduces charge transfer resistance and facilitate the ORR. The porous 2D structure also contributes to the increase of active site density and facile mass transport.

Stabilizing interactions between charged electrocatalytic intermediates and a series of cationic residues were explored through the synthesis and characterization of six palladium bis(N-heterocyclic carbene) (NHC) complexes bearing unique onium functionalities. The presence of a positively charged, pendant substituent was found to mediate electrode kinetics and facilitate CO2 coordination to the catalytic center in a systematic fashion. The introduction of cationic moieties into this system is shown to enhance catalytic selectivity for the conversion of CO2 to CO by as much as 5 times that of an alkyl-bearing analog. A combination of electrochemical experiments and computational analysis demonstrates that catalyst performance benefits most from a bulky onium unit tethered to the catalyst through a flexible linker. This behavior was interpreted as a preference for a wide, hydrophobic reaction pocket that allows for the unhindered formation of catalytic intermediates and mediated interaction with the solution.

The reaction products formed in the SO2–L–H2O–O2 systems (L is n-propylamine, n-butylamine, tert-butylamine, n-heptylamine, n-octylamine, aniline) were isolated and identified as “onium” salts [n-C3H7NH3]2SO4, [n-C4H9NH3]2SO4, [t-C4H9NH3]2SO4, [n-C7H15NH3]3SO4(HSO4), [n-C8H17NH3]3SO4(HSO4), and [C6H5NH3]2SO4. The products were characterized by elemental analysis, IR and Raman spectroscopy, mass spectrometry, and thermogravimetry.

In recent years, solvate and protic ionic liquids (ILs) have attracted much attention. We synthesized both types of ILs from alkyl aza-crown ethers (L = N-propyl-1-aza-15-crown-5 (L1) and N-C6F13C2H4-1-aza-15-crown-5 (L2)). The solvate ILs [ML][Tf2N] (M = Na+, K+) were solids (Tm = 58-68 °C), whereas the solvate ILs [ML][Tf2N] (M = Li+, Ag+) and protic ILs [HL][Tf2N] were liquids with low glass transition temperatures. The ILs containing Na ions were more crystalline and exhibited higher melting points than the other ILs. The decomposition temperatures of the protic ILs were higher than those of the solvate ILs. A protic IL with a paramagnetic anion, [HL1][FeCl4] (Tm = 70.5 °C), was also synthesized and its crystal structure was determined. The solvate ILs [NaL2][X] (X = Cl−, CF3CO2−, TsO−, PhSO3−) exhibited a lower critical solution temperature (LCST)-type behavior in water. The effects of salt addition on the LCST of L2 were also investigated. The LCST of these ILs generally increased with increasing hydrophilicity or basicity of the counter anion. This tendency, which is nearly opposite to that of ILs with quaternary onium cations, is ascribed to the amphiphilic nature of the cation. The corresponding protic ILs did not exhibit LCST behavior.

Reaction products have been isolated from SO2–L–H2O–О2 systems (L = ethylenediamine, N,N,N′,N′-tetramethylethylenediamine, piperazine, and morpholine) as onium salts [H3NCH2CH2NH3]SO4, [(CH3)2NHCH2CH2NH(CH3)2]SO4, [(CH3)2NHCH2CH2NH(CH3)2]S2O6 ⋅ H2O, [C4H8N2H4]SO3 ⋅ H2O, [C4H8N2H4]S2O6, [C4H8N2H4]SO4 ⋅ H2O, [O(C2H4)2NH2]2SO4 ⋅ H2O. The prepared compounds have been characterized by X-ray diffraction analysis, X-ray powder diffraction, IR and mass spectroscopy.

According to the new-designed method of synthesis the solid coordination compounds of Germanium (IV) with galactaric acid (H6Gala), Mg2+, Ca2+, Ba2+ ions and exo-ligands (isoniazidе (Ind) and nicotinamidе (Nad)) were obtained: M(Н2О)6][Ge2(μ-HGala)2]·nH2O (M= Mg (I), Ca (II), Ba (III)), (НL)2[Ge2(μ-HGala)2] (L = Ind (IV) and Nad (V)). Due to the data of elemental analyses the molar ration in compounds I-III is Ge : НGala5– : M (Mg2+, Ca2+, Ba2+) =1:1:0.5 and in IV, V – Ge : НGalа5– : L (Ind, Nad)= 1:1:1. Comparatively to the spectrum of initial acid, in the IR-spectra of compounds I-V the stretching vibrations of СООН group are absent and symmetrical and asymmetrical valence vibrations of СОО– ions appear. Consequently carboxylic groups of ligand are deprotonated and bonded with Germanium atom monodentate (Δν = νas(COO-) – νs(COO-) ~ 332 см-1). This was confirmed by presence of Ge-O valence vibrations. The molecular formulas of the compounds I-V and their preparation reactions were suggested due to the data of elemental analyses, thermogravimetry (presence of 6 coordinated water molecules and 2 (I, III) or 6 (III) crystallization water molecules) and IR-spectroscopy: 2GeO2 + 2H6Gala + MСO3 + (1+x)H2O = [M(Н2О)6][Ge2(μ-НGala)2]·xH2O(I-III) + CO2 2GeO2 + 2H6Gala + 2L = (НL)2[Ge2(μ-НGala)2] (IV,V) + 5H2O

Chemically-synthesized semiconductor nanostructures have the potentials for the exploration of unprecedented electronic and thermoelectric properties. Such materials possess the surface area much larger than their bulk forms, resulting that surface chemical functionalization may alter electronic properties. Here we report on the modulation of majority carriers in semiconductor nanowires by the addition of organic salts. The p-type nanowires were successfully converted to n-type forms to which large cations such as onium ions and metal-crown ether complexes are coordinated.

In this work, we investigated the effects of counter anions, P-substituents, and solvents on the optical and photophysical properties of 2-phenylbenzo[b]phospholium salts in solution. A series of 2-phenylbenzo[b]phospholium salts was prepared by P-alkylation or P-phenylation of 1,2-diphenylbenzo[b]phosphole followed by anion exchange reactions. X-ray crystallographic analyses of six benzo[b]phospholium salts showed that each phosphorus center has an onium nature with an essentially tetrahedral geometry. 1H NMR and steady-state UV-vis absorption and fluorescence spectroscopic measurements of these phospholium salts revealed the pivotal role of counter-anion solvation. The observed results are discussed on the basis of the association-dissociation equilibrium between a contact ion pair (CIP) and a solvent-separated ion pair (SSIP) in solution. The hexafluorophosphates exist as SSIPs and emit intense fluorescence, irrespective of the P-substituents and solvents. In contrast, the iodides are present as SSIPs in methanol but exist as equilibrium mixtures of the two emitting species, SSIP and CIP, in dichloromethane. As a consequence, fluorescence intensities of the iodides varied significantly depending on the solvents, P-substituents, and solution concentrations. These findings were studied in more detail using time-resolved fluorescence spectroscopy and fluorescence titration measurements. The light-emitting properties of the 2-phenylbenzo[b]phospholium halides in the CIPs rely on heavy atom effects derived from the counter halide anions on the S1 state of the adjacent cationic benzo[b]phosphole π-systems. The present study suggests that 2-arylbenzo[b]phospholium salts would be promising scaffolds for developing new phosphole-based ionic fluorophores that are capable of responding to external stimuli such as anionic species and solvents.

Titanium(IV) complexes bearing an unsubstituted tridentate bis(phenolate) N-heterocyclic carbene (NHC) were synthesized and structurally identified. While sterically unencumbered NHC–Ti(IV) complexes bearing chloro and alkoxy co-ligands tend to dimerize in solution and in solid-state, the use of a bulky aryloxy as co-ligand favors the monomeric species. Upon activation by onium salts, all these complexes were found to be highly selective towards the copolymerization of cyclohexene oxide (CHO) with CO2 under mild conditions (PCO2 < 1 bar), albeit the sterically unencumbered NHC–Ti(IV) complexes are less stable and active than their structural analogues bearing bulkier substituents.

The reaction between sulfur(IV) oxide and aqueous methylamine yields “onium” sulfate (CH3NH3)2SO4, which was characterized by X-ray diffraction, IR spectroscopy, and mass spectrometry. The structure of the sulfate is stabilized by a network of NH⋅⋅⋅O hydrogen bonds.

The catalytic coupling of oxetane, the symmetric isomer of propylene oxide, with carbon disulfide has been investigated utilizing (salen)CrCl in the presence of various onium salts. Oxygen and sulfur atom exchange was observed in both the polymeric and cyclic carbonate products. The coupling of oxetane and CS2 was selective for copolymer formation over a wide range of reaction conditions. Five different polymer linkages and two cyclic products were determined by 1H and 13C NMR spectroscopy, and these results were consistent with in situ infrared spectroscopic monitoring of the process. The major cyclic product produced in the coupling process was trimethylene trithiocarbonate, which was isolated and characterized by single crystal X-ray crystallography. Upon increasing the CS2/oxetane feed ratio, a decrease in the O/S scrambling occurred. The reaction temperature had the most significant effect on the O/S exchange process, increasing exchange with increasing temperature. The presence of the onium salt ini...

Here, we report maintenance-free cellulose solvents that dissolve much cellulose within a few minutes under mild conditions even in the presence of water. We have examined a series of aqueous solutions of tetraalky-phosphonium and tetraalkyl-ammonium hydroxides to clarify the effect of cation species on cellulose dissolving. Aqueous solutions of the many hydroxides examined here were found to dissolve cellulose at room temperature, and electrostatic interaction and/or steric hindrance of component ions are suggested to affect the cellulose-dissolving ability. In spite of increasing water content after dissolution of wet cellulose, the water content automatically reduced to less than 60% just by keeping the filtrated solution in the air. The solvation state of cellulose in aqueous onium hydroxide solutions is discussed with 13C NMR chemical shift of cellobiose signals in these solutions. They dissolve cellulose only when the 13C NMR signal of the carbon atom at the 12 position of cellobiose is 64.8 ppm or ...

Data of potentiometric, redox, and conductometric studies of interactions in the sulfur(IV) oxide-ethylenediamine (or its analogs)-water systems, being in fair agreement, have showed the formation of onium sulfites, hydrosulfites, and pyrosulfites. The absorbance capacity of aqueous solutions of ethylenediamines with respect to sulfur dioxide depends on the amino groups amount. Ion and molecular compositions of the studied solutions have been computed, and the relative stability of onium sulfites of ethylenediamine and piperazine has been estimated.

The copolymerization of 1,3-cyclohexadiene oxide (1,2-epoxy-3-cyclohexene) with CO2 in the presence of the binary catalyst (salen)CoX or (salen)CrX and onium salts was shown to selectively afford the completely alternating copolymer poly(1,3-cyclohexadiene carbonate) in good yield. In the process catalyzed by the cobalt(III) system, the reaction was 100% selective for copolymer, whereas employing the higher temperature chromium(III) catalyst, the reaction yielded in addition to copolymer a significant quantity of the cis-1,3-cyclohexadiene carbonate. Importantly, no corresponding trans-1,3-cyclohexadiene carbonate was produced. The reactivity of 1,3-cyclohexadiene oxide in coupling reactions with CO2 was strikingly greater than that of 1,4-cyclohexadiene oxide under either catalytic conditions. Authentic samples of the cis-cyclic carbonate and trans-cyclic carbonate were synthesized from epoxide and CO2 using ZnCl2/PPNI catalyzed and trans-diol/ethyl chloroformate routes, respectively. trans-1,3-Cyclohexa...

Dodecylbenezenesulfonate-based anionic surface active ionic liquids (DBS-ILs) paired with onium cations, n-butyltrimethylammonium ([N1114]), 1-butyl-3-methylimidazolium ([C4mim]), and N-butylpyridinium ([C4Py]) have been synthesized. DBS-ILs were found to be highly surface active having critical micelle concentration (CMC) lower than that of their conventional analogue sodium dodecylbenezenesulfonate ([Na][DBS]). The CMC values of DBS-ILs were determined from surface tension (ST) and isothermal titration calorimetry (ITC). DBS-ILs formed micelles predominantly in the aqueous medium, and unlike [Na]DBS, the micelles of DBS-ILs could be transformed into vesicles with the addition of sodium bromide (NaBr). Micelle to vesicle transitions (MVTs) were evidenced from dynamic light scattering (DLS), turbidity, proton nuclear magnetic resonance ((1)H NMR), and cryo-TEM techniques. Thermodynamics of aggregation was investigated from ITC which indicated that the aggregation process is primarily driven by the entropy factor. The formation of a vesicle upon addition of NaBr has been accounted to the increased electrostatic interactions between the less hydrated sulfonate headgroup and the more populated bigger sized counterions along with the favored cation-π or π-π interactions between them as evidenced from 2D-NOESY NMR experiments. The stimuli-responsive morphological transitions in the self-assembly of the reported anionic surface active ionic liquids (SAILs) will be useful for encapsulation and delivery of active (bio)molecules in the targeted biomedical applications.

The use of ion/ion reactions to effect gas-phase alkylation is demonstrated. Commonly used fixed-charge "onium" cations are well-suited for ion/ion reactions with multiply deprotonated analytes because of their tendency to form long-lived electrostatic complexes. Activation of these complexes results in an SN2 reaction that yields an alkylated anion with the loss of a neutral remnant of the reagent. This alkylation process forms the basis of a general method for alkylation of deprotonated analytes generated via electrospray, and is demonstrated on a variety of anionic sites. SN2 reactions of this nature are demonstrated empirically and characterized using density functional theory (DFT). This method for modification in the gas phase is extended to the transfer of larger and more complex R groups that can be used in later gas-phase synthesis steps. For example, N-cyclohexyl-N'-(2-morpholinoethyl)carbodiimide (CMC) is used to transfer a carbodiimide functionality to a peptide anion containing a carboxylic acid. Subsequent activation yields a selective reaction between the transferred carbodiimide group and a carboxylic acid, suggesting the carbodiimide functionality is retained through the transfer process. Many different R groups are transferable using this method, allowing for new possibilities for charge manipulation and derivatization in the gas phase.

Onium bis(citrate)germanates (HNad)2[Ge(HCit)2] · 4H2O (I), (HIm)2[Ge(HCit)2] · 2H2O (II), and (HInd)2[Ge(HCit)2] · 2H2O (III) (where Nad is nicotinamide, Im is imidazole, and Ind is isoniazid) were synthesized by the reaction between bis(citrate)hydroxogermanic(IV) acid (H5O2)[Ge(OH)(H2Cit)(H2.5Cit)]2 · 2CH3COOH · 2H2O (H4Cit is citric acid) and organic bases. The complexes were characterized by elemental analysis, thermogravimetry, and IR spectroscopy. The X-ray diffraction analysis of complex I was performed. The structural units of a crystal of complex I were found to be centrosymmetric complex [Ge(HCit)2]2− anions, HNad+ cations, and crystallization water molecules.

Introduction Today as potential caries-preventive agents hexafluorosilicate ammonium and hexafluorosilicates organic "onium" cations actively studied, which have certain advantages over traditional means of fluoride treatment and prevention of tooth decay. Among these compounds are exposed to saliva hydrolysis to form a soluble form of silica that catalyzes the formation of phosphate sludge (fluoride) calcium and provides prolonged occlusion tubul dentin. As one of the most important physical and chemical characteristics of drugs is their solubility in water and hydrolytic instability, because the purpose of the present study investigated the solubility in water, hydrolytic instability and potential biological activity of 3,5-disubstituted 1,2,4-triazolium hexafluorosilicates in order to estimate their potential use as caries-preventive agents.Investigation methods The method of synthesis hexafluorosilicates (LH)2SiF6 * nH2O (L1 = 3-pyridine-3-yl-5- (2'-aminophenyl) -1H-1,2,4-triazole, n = 1; L2 = 3-benzofuran- 2-yl-5- (2'-amino-3'-methyl-phenyl) -1H-1,2,4-triazole, n = 1; L3 = 5- (2'-amino-5'-chloro-phenyl) -3-furan-3-yl-1H-1,2,4-triazole, n = 1; L4 = 3-adamantane-1-yl-5- (2'-amino-phenyl) -1H-1,2 4-triazole, n = 2; L5 = 5- (2'-amino-3'-methyl-phenyl) -3-furan-3-yl-1H-1,2,4-triazole, n = 1; L6 = 3-thiophene-3-yl-5- (2'-amino-3'-fluoro-phenyl) -1H-1,2,4-triazole, n = 2; L7 = 3-thiophene-2-yl-5 - (2'-amino-3'-fluoro-phenyl) -1H-1,2,4-triazole, n = 3). Working 1×10-4 Maqueous salt solutions were prepared in a plastic container. Determination of the soluble form of silica products of hydrolysis hexafluorosilicates conducted photocolorimetric method. The measurement was performed at a wavelength of 380 nm.Results and discussion We found a general tendency to reduce the values of α for hexafluorosilicates 1,2,4-triazole compared with pyridinium salts, which is close to the degree of hydrolysis quantity. In the case of salts of 1,2,4-triazole less efficient release of fluoride ions by hydrolysis circuits may be accompanied by a decrease caries-preventive effect of the studied compounds. During the preparation 1×10-4 M salt solutions in all cases observed precipitate soluble free base L by hydrolysis in cation. For a given concentration of solutions villages are not subjected to further dissolution prolonged aging, to evaluate the upper limit of solubility of salts of 1,2,4-triazole in ≤ 0.0002 mol. %. Very low solubility studied in this paper salts of 3,5-disubstituted 1,2,4-triazole derivatives and 3,5-diamino-1,2,4-triazole related obviously dominated lipophilic contribution to the hydrophilic-lipophilic balance heterocyclic bases L1 - L7.Conclusions Estimated value of solubility hexafluorosilicates 3,5-disubstituted 1,2,4-triazole derivatives in water in the lowest number of similar salts of heterocyclic cations. The degree of hydrolysis of 1,2,4-triazole hexafluorosilicates in aqueous solution by an average of 10 - 30% lower compared with the corresponding values for pyridinium salts. The experimental and calculated data do not consider hexafluorosilicates 3,5-disubstituted 1,2,4-triazole derivatives as promising caries-preventive agents.

The present research has studied the spectral data, thermochemical transformations and hydrolysis of hexafluorosilicates with guanidine containing cations (C22H32Cl2N10)SіF6 (І) and (C21H45N9)(SiF6)1.5 (ІІ) for their potential use as caries-preventive and antibacterial agents. Hexafluorosilicates of the com position I and II were separated as crystalline products of interaction of hexafluorosilicic acid with the methanol solutions of chlorhexidine hydrochloride and polyhexamethylene guanidine hydrochloride. The compounds isolated have been characterized by IR, NMR 19 F, mass-spectrometry, thermogravimetric analysis, potentiometry. According to IR spectroscopy data, “onium” hexafluorosilicates I and II have ionic structures. The vibrations of the groups ν(NH), ν(N + H2) in salts I and II appear as strong absorption bands at 3360-3180 cm –1 ; δ(N + H2) vibrations appear at 1634 and 1637 cm –1 . The strong ν(SiF) and δ(SiF2) stretches of SiF6 2– anions are observed in their characteristic regions (at 744, 734 and 482 cm –1 , respectively). The singlet character of ν(SiF) and δ(SiF2) vibrations indicates the absence of noticeable distortion of symmetry of SiF6 2– anion with regard to Oh. The NMR 19 F spectra of compounds I and II (in DMSO-d6 solutions) have one resonance at –136,70, –135,09 ppm (SiF6 2– ); additional resonance at –123,14 ppm, in the case of II it can be related to the octahedral complex anion [SіF5(ДМСО)] – . The results of thermogravimetric analysis are consistent with a multi-stage thermolysis scheme for hexafluorosilicates I and II. The temperatures of thermolysis beginning of complexes I and II are 270 and 100°C, respectively. The compounds I and II studied are characterized by the predicted tendency to hydrolysis in dilute aqueous solutions with formation of orthosilicic acid and fluoride ions, and it allows considering these salts as potential anticaries agents. The study of the biological activity of these compounds is the subject of further investigations. In recent years, several research groups consisting of experts from Japan, the United States [10-13] and Armenia [1, 8] demonstrated the possible use of ammonium and amino acids hexafluorosilicates as caries-preventive and hyposensitive agents in dental practice. These results [1, 8, 10-13] allow to consider the “onium” hexafluoro silicates as a promising new class of drugs possessing a number of advantages compared to the conventional agents of fluoride caries therapy such as sodium and po tassium fluorides, silver diamine fluoride, tin fluoride and sodium monofluorophosphate. The active components of treatment and prevention of dental caries are also antibacterial agents, including high efficient guanidine de rivatives (chlorhexidine, polyhexamethylene guanidine hydrochloride, etc.) [9, 13]. In principle, introducing guanidine containing cations possessing the antibacterial action into the composition of hexafluorosilicate allows to obtain compounds for which the caries-preventive effect of the anion is intensified by the bactericidal action of the cation. The aim of this work is the synthesis, the study of the structure and properties of chlorhexidine (CH) and polyhexamethylene guanidine (PHMG) hexafluorosilicates – the first representatives of fluoride-containing salts com bined with cations exhibiting the antibacterial activity. Materials and Methods The synthesis of hexafluorosilicates was performed by the ion exchange reaction between methanol solu

A highly efficient method for the synthesis of cyclic carbonates from carbon dioxide and epoxides in the presence of polymer-supported quaternary onium salts (PS-Q + X − ) and aqueous solution of metal salts under mild conditions, is described. In comparison with conventional homogeneous catalysts, immobilized tributylmethylammonium chloride (PS-TBMAC) is a recyclable, effective catalyst for the studied reaction. The presence of an aqueous solution of zinc iodide as a co-catalyst enhances significantly the catalytic activity of PS-TBMAC. Using this two-component catalyst system (polymer-supported quaternary onium salts and aqueous solution of metal salts), the reaction of CO 2 with selected epoxides can be conducted with high product yield (71–91%) and selectivity (97–99%) under mild reaction conditions (temperature 110 °C and initial CO 2 pressure 0.9 MPa). Propylene carbonate was obtained in the best yield (91%). In addition, the advantages of this method include a short reaction time, solvent-free conditions, and an easy separation of catalyst system.

A reaction between sulfur(IV) oxide and aqueous N-(2-hydroxyethyl)ethylenediamine yields onium sulfite of composition (HOCH2CH2NH2CH2CH2NH3)SO3 · H2O, which has been characterized by X-ray diffraction, IR spectroscopy, and mass spectrometry. The three-dimensional structure of the salt is stabilized by numerous hydrogen bonds, such as NH…O and OH…O.

A coordination effect was employed to realize equimolar CO2 absorption, adopting easily synthesized amino group containing absorbents (alkali metal onium salts). The essence of our strategy was to increase the steric hindrance of cations so as to enhance a carbamic acid pathway for CO2 capture. Our easily synthesized alkali metal amino acid salts or phenolates were coordinated with crown ethers, in which highly sterically hindered cations were obtained through a strong coordination effect of crown ethers with alkali metal cations. For example, a CO2 capacity of 0.99 was attained by potassium prolinate/18-crown-6, being characterized by NMR, FT-IR, and quantum chemistry calculations to go through a carbamic acid formation pathway. The captured CO2 can be stripped under very mild conditions (50 °C, N2). Thus, this protocol offers an alternative for the development of technological innovation towards efficient and low energy processes for carbon capture and sequestration.

Bis(triphenylphosphine)gold(I) perrhenate [Ph3PAuPPh3]+ReO4 - has been prepared in high yield from Ph3PAuCl, Ph3P and AgReO4 in a mixed solvent. The compound is stable in air and decomposes at 235 °C. In the crystal structure, the two independent perrhenate anions are not approaching the gold centers of the two independent cations, but weak interionic interactions are entertained via π-π stacking of phenyl groups and C-H···O contacts. As three-blade chiral rotors, the Ph3P ligands of the cations are in a staggered conformation at the gold atoms with only slightly bent P-Au-P axes. IR and NMR data show no anomalies and are close to those of alkali or onium perrhenates.

The catalytic coupling of cyclopentene oxide with carbon disulfide has been investigated utilizing (salen)CrCl in the presence of added onium salts. Both polymeric and cyclic materials were produced, with oxygen/sulfur atom scrambling observed in both instances. This atom redistribution process was found to require (salen)CrCl and excess epoxide, though an increase in the rate of atom scrambling was noted upon the addition of the onium salt. Cyclopentene sulfide was observed as a side product of the coupling reaction and was found to be unreactive toward both CS2 and CO2, instead undergoing desulfurization to cyclopentene under the conditions of the reaction. Of the 12 cyclic cyclopentene [thio]carbonates possibly produced by this coupling reaction, eight were observed, and the crystal structure of trans-cyclopentene trithiocarbonate is reported herein. Computational studies reveal that the cis- cyclic materials are more stable than their trans-counterparts by >5 kcal/mol of enthalpy, and there is a 10–25...

The reaction between sulfur(IV) oxide and an aqueous suspension of aminoguanidinium hydrocarbonate yields (CN4H7)2SO3 · H2O, an “onium” sulfite, which has been characterized by X-ray diffraction and IR spectroscopy and mass spectrometry. The structure of the salt is stabilized by numerous H-bonds, such as NH…O, OH…O, and NH…N. The incorporation of pyramidal SO 3 2− ions into the network of H-bonds is accompanied by the lowering of their symmetry in comparison with C 3v, thus complicating the IR spectra of the salt in the region where the vibrations of the anion appear.

The thermal decomposition of cellulose treated with tetrakis(hydroxymethyl) phosph- onium chloride (THPC), urea and ammonium dihydrogen phosphate (ADP) and its metal complexes was studies by TG, DTA and CONE. The activation energies for the second stage of thermal degradation have been obtained by following the Broido equation. Experimental data show that for the complexes of cell-THPC-urea-ADP with metal ions, the activation energies and thermal decomposition temperatures are higher than those of cell-THPC-urea-ADP, which shows these metal ions can increase the thermal stability of cell-THPC-urea-ADP. Moreover, Ni(Ⅱ), and Zn(Ⅱ) can more increase thermal stability of samples than Co(Ⅱ). The CONE data indicate that the transition metals have smoke suspension on cell-THPC-urea-ADP. Moreover, Co(Ⅱ) has more effect than Ni(Ⅱ), and Zn(Ⅱ) in the smoke suspension.

The combustion behavior of triaminoguanidine nitrate (TAGN) was investigated over a wide pressure range and a detailed combustion mechanism has been proposed. Temperature profiles in the TAGN combustion wave were measured with thin tungsten-rhenium microthermocouples. It was shown that the surface temperature in combustion of TAGN as well as for other onium salts is controlled by the process of dissociation. The burning rate of TAGN is governed by processes in the condensed phase.

Using quantum mechanical calculations performed at the density functional level of theory, the present study explores the binding energetics, orbital energies, and charge transfer behavior accompanying sorption of 12 different ionic liquids (ILs) onto 6 archetypal polyaromatic hydrocarbons (PAHs). The ILs were based on combinations of three different onium cations (i.e., 1-butyl-3-methylimidazolium, 1-butylpyridinium, 1-butyl-1-methylpyrrolidinium) paired with four common anions, that is, bromide, tetrafluoroborate, hexafluorophosphate, and bis(trifluoromethylsulfonyl)imide. In general, the size of the anion as well as interaction of the butyl side chain present on the cation with the paired anion exerted significant influence over the cation ring orientation with respect to the PAH surface. A smaller highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) energy band gap was observed for pyridinium-based ILs upon adsorption on the PAH surface in comparison to imidazolium and py...

The possibility of mild SO2 oxidation in sulfur(IV) oxide-alkylamine-water-oxygen systems is demonstrated to yield onium sulfates.

Potentio- and conductometric titration was used to study the interaction in sulfur(IV) oxide-ethanolamines-water systems in comparison with the previously obtained pH-metric data on how the corresponding onium sulfites, hydrosulfites, and pyrosulfites are formed. The ionic and molecular compositions of these solutions were calculated. Correlations between the characteristics of pH-metric titration curves of aqueous solutions of ethanolamines with sulfur(IV) oxide and the relative stability of onium sulfates were revealed.

The solution structure of the phosphocholine (PC) head group in 1,2-dipropionyl-sn-glycero-3-phosphocholine (C(3)-PC) in 30 mol. % dimethylsulfoxide (DMSO)-water solutions has been determined by using neutron diffraction enhanced with isotopic substitution in combination with computer simulation techniques. By investigating the atomic scale hydration structure around the PC head group, a unique description of the displacement of water molecules by DMSO molecules is detailed around various locations of the head group. Specifically, DMSO molecules were found to be the most prevalent around the onium portion of the head group, with the dipoles of the DMSO molecules being aligned where the negatively charged oxygen can interact strongly with the positively charged lipid group. The phosphate group is also partially dehydrated by the presence of the DMSO molecules. However, around this group the bulkier positive end of the DMSO dipole is interacting with negatively charged groups of the lipid head group, the DMSO layer shows no obvious ordering as it cannot form hydrogen bonds with the oxygen atoms in the PO(4) group such as water molecules can. Interestingly, DMSO-water contacts have also increased in the presence of the lipid molecule relative to DMSO-water contacts observed in pure DMSO/water solutions at similar concentrations.

Polyoxomolybdate-based organic−inorganic hybrid architectures were synthesised and characterised by X-ray crystallography. The supramolecular assemblies present rows of metallic clusters H-bonded by ammonium cations, with a 1:2 molybdate/ammonium ratio. The organic moieties of the ammonium cations establish hydrophobic contact among them such as van der Waals, C–H⋯π and π⋯π interactions that stabilise the supramolecular architectures. In particular, for compound 5 the n-alkyl tails pack closely together giving a lipid-like bilayer. In compound 6, the aromatic phenyl rings of the organic cation allow the stabilisation of the supramolecular architecture by C–H⋯π and π⋯π interactions. Regarding the X-ray structure of the compound 11, the tetraanionic octa-molybdate [Mo8O26]4− cluster is surrounded by four ethyl-triphenyl-phosphonium cations. Running along the b-axis open channels are occupied by DMF solvent molecules. Interestingly, a soaking experiment in n-pentane with the corresponding crystals of compound 11 afforded to a crystal structure very different from the native one. Van der Waals, C–H⋯π and π⋯π interactions between large organic moieties are fundamental in the stabilization of hybrid organic-inorganic POM architectures.

Dialkyl imidazoline, alkyl pyridine and alkyl quinoline containing salts have been synthesized and used as new surfactants for cationic exchange of layered silicates, such as montmorillonite (MMT) in order to evaluate their role in the formation of intercalated MMT clays. The new salts have been characterized by FTIR, 1H, 13C-NMR spectra. These compounds have been intercalated into the layers of MMT via a solution dispersion technique and the extent of the interlayer space expansion was confirmed by using wide angle X-ray diffraction and FTIR spectra. Thermogravimetry analysis shows that these salts can be used in place of ammonium salts to produce organophilic clays with higher thermal stability than commercial alkyl ammonium-treated MMT. Moreover, the results also show that the imidazolium-modified clays have a greater thermal stability compared to the quinolinium and the pyridinium-modified clay. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Quaternary onium salts of halides can be efficiently converted into the corresponding quaternary onium salts of various anions [NO3–, BF4–, PF6–, CF3SO3–, CH3SO3–, ClO4–, p-CH3C6H4SO3–, CF3CO2–, 2,4-(NO2)2C6H3O–] by treating the onium halide with trimethyl phosphate under neat condition in the presence of an equivalent amount of conjugate acid of the desired anion.

Relations were investigated between the structure of a series of onium salts, rates of alkaline hydrolysis catalyzed by the salts of 4-nitrophenyl N-benzyloxycarbonylglycinate in a two-phase liquid-liquid system, and the value of the standard exchange enthalpy of anions in ion pairs with the catalyst cation calculated by the semiempiric PM3 method. The catalytic activity of ammonium, phosphonium, pyridinium, imidazolium, and benzimidazolium salts in a wide range of cation structures varies in parallel with the enthalpy of formation of the active form of the catalyst by the exchange of the anion with a hydroxide ion.

Copolymerization of a series of cyclic acid anhydrides with several epoxides using (salen)CrCl/onium salt catalysts has afforded polyesters with high molecular weights and narrow molecular weight distributions. The (salen)CrCl catalyst in the presence of the onium salts with formula PPNX (X = Cl–, N3–) for the copolymerization of the anhydrides, maleic (MA), succinic (SA), phthalic (PA), cyclohexene (CHE), and cyclohexane (CHA) with the epoxides, cyclohexene oxide (CHO), propylene oxide (PO), and styrene oxide (SO) resulted in completely alternating enchainment of monomers to provide pure polyesters. Temperature dependent studies of the ring-opening copolymerization of phthalic anhydride and cyclohexene oxide monomers in toluene solution have yielded activation parameters of ΔH‡ = 67.5 kJ mol–1 and ΔS‡ = −95.3 J mol–1, where the rate limiting step was ring-opening of the epoxide by the enchained anhydride. For the cyclic acid anhydride (CHA), the relative order of reactivity with epoxides decreased PO > C...

The relationship between the water solubility of hexafluorosilicates with different types of onium cations and the characteristics of interionic H-bonds in their structures was analyzed. The antibate correlation between the solubility and the number of short interionic H-bonds was revealed for salts with aromatic heterocyclic and arylammonium cations.

A combustion model controlled by condensed-phase reactions (c-phase combustion model) is considered. Based on an analysis of numerous thermocouple studies of combustion of energetic materials, it is shown that the condensed phase is heated in the combustion wave to the maximum possible temperature—the boiling point at this pressure. It is established that the combustion of representatives of the class of onium salts such as ammonium perchlorate, ammonium nitrate, ammonium dinitramide, and hydrazinium nitroformate over a wide range of pressures and initial temperatures obeys the the c-phase-model. The kinetic parameters of the burning-rate controlling reaction of these salts are given.

A series of chiral salen Mn(III) immobilized onto azole onium modified zinc poly(styrene-phenylvinyl phosphonate)-phosphate (ZnPS-PVPA) were prepared. The catalysts were characterized by FT-IR, diffusion reflection UV-vis, AAS, N(2) volumetric adsorption, SEM, TEM, XPS, XRD, TG and elemental analysis. The results showed that the chiral salen Mn(III) complex was successfully immobilized onto ZnPS-PVPA. These prepared catalysts were evaluated in the asymmetric epoxidation of unfunctionalized olefins with m-CPBA and NaIO(4) as oxidants and demonstrated higher catalytic activities than those of the corresponding homogeneous chiral salen Mn(III) catalyst under the same conditions. Moreover, these heterogeneous catalysts were stable and could be recycled nine times without significant loss of activity. Furthermore, this novel type of catalyst could also be validly used in large-scale reactions with superior catalytic disposition being maintained at the same level, which indicated the potential for applications in industry.

To improve the practicality and safety of a novel explosive dihydroxylamm onium 5,5'-bis (tetrazole)-1,1'-diolate (TKX-50), polyvinylidene difluoride (PVDF) and polychlorotrifluoroe-thylene (PCTFE) were respectively added to the TKX-50, forming the polymer-bonded explosives (PBX). Interfacial and mechanical properties of PBX were investigated through molecular dynamics (MD) method, desensitizing mechanisms of fluorine-polymers for TKX-50 were researched by compression and bulk shear simulations. Results show that the binding energies (E bind ) between polymers (PVDF or PCTFE) and TKX-50 surfaces all rank in order of (011) > (100) > (010), shorter interatomic distance and the resulted higher potentials lead to higher E bind on TKX-50/PVDF interfaces than that on PCTFE/TKX-50 interfaces. Compared with TKX-50, the ductility of PBX is improved due to the isotropic mechanical property and flexibility of fluorine-polymers especially the PCTFE. Desensitizing effect of fluorine-polymers for TKX-50 is found under loading condition, which is attributed to the enhanced compressibility and buffer capacity against external pressure in compression, as well as the improved lubricity to reduce the sliding potentials in bulk shear process. Graphical Abstract Comparisons of the internal stress and slide potentials of the novel explosive,TKX-50 and its based PBX. Desensitizing effects can be found by the adding of fluorine-polymers, it owes to their better flexibility and lubricity as well as the amorphous nature.

By direct reactions of selenium with halogen and trimethylphenylammonium halogenide and tetraphenylphosphonium, ethyltriphenylphosphonium, and methyltriphenylphosphonium bromides, the tetrahalogenidoselenates(II) – bis(trimethylphenylammonium)tetrabromidoselenate(II) bromide, [NPhMe3]2[SeBr4]·[NPhMe3]Br, a mixed bis(trimethylphenylammonium) tetra(bromido/chlorido)selenate(II), [NPhMe3]2[SeBr4–xClx]·[NPhMe3]2SeBr1–yCly], [NPhMe3]2[SeBr4–xClx],the haxahalogenidodiselenates(II) – bis(trimethylphenylammonium) hexabromidodiselenate(II), [NPhMe3]2[Se2Br6], bis(trimethylphenylammonium) hexachloridodiselenate(II), [NPhMe3]2[Se2Cl6], a mixed bis(trimethylphenylammonium) bromido/chlorido-diselenate(II), [NPhMe3]2[Se2Br5Cl], bis(tetraphenylphosphonium) hexabromidodiselenate(II), [PPh4]2[Se2Br6], bis(ethyltriphenylphosphonium) hexabromidodiselenate(II), [PEtPh3]2[Se2Br6], and bis(methyltriphenylphosphonium) hexabromidodiselenate(II), [PMePh3]2[Se2Br6], were prepared. By the reaction of selenium with bromine in acetonitrile in the presence of trimethylphenylammonium, benzyltrimethylammonium, and tetramethylammonium bromides, the salts of the unique bromidoselenate(I) anions – bis(trimethylphenylammonium) hexabromidotetraselenate(I), [NPhMe3]2[Se4Br6], bis(benzyltrimethylammonium) hexabromidotetraselenate(I), [NBzMe3]2[Se4Br6], and bis(tetramethylammonium) octadecabromidohexadecaselenate(I), [NMe4]2[Se16Br18], were isolated. First mixed-valence bromidoselenates(II/I) – bis(tetraethylammonium) octabromidotriselenate(II){dibromidodiselenate(I)}, [NEt4]2[Se3Br8(Se2Br2)], bis(tetraphenylphosphonium) hexabromidodiselenate(II)-bis{dibromidodiselenate(I)}, [PPh4]2[Se2Br6(Se2Br2)2], and tetrakis(tetramethylammonium) bis{decabromidotetraselenate(II)}-bis{dibromidodiselenate(I)}, [(CH3)4N]4[(Se4Br10)2(Se2Br2)2] – were synthesized. Mixed bis(trimethylphenylammonium) hexabromidoselenate/tellurate(IV), [NPhMe3]2[Se0.75Te0.25Br6], catena-poly[(di-μ-bromidobis-{tetrabromidoselenate/tellurate(IV)})- μ-bromine], [NPhMe3]2n[Se1.5Te0.5Br10·Br2]n were isolated. First mixed-valence bromidoselenate(IV/I)-bis(trimethylphenylammonium) hexabromidoselenate(IV)-bis{dibromidodiselenate(I)}, [NPhMe3]2[SeBr6(Se2Br2)2], a number of mixed bromidochalcogenates(IV/I) – bis(trimethylphenylammonium), bis(tetraethylphosphonium), bis(ethyltriphenylphosphonium) hexabromidotellurates(IV)-bis{dibromidodiselenates(I)}, [NPhMe3]2[TeBr6(Se2Br2)2], [PEt4]2[TeBr6(Se2Br2)2], [PEtPh3]2[TeBr6(Se2Br2)2], bis(triethylmethylammonium) hexabromidotellurate(IV)-tris{dibromidodiselenate(I)}, [NMeEt3]2n[TeBr6(Se2Br2)3]n, were synthesized. Mixed-valence bromidoselenate(IV/II) – bis(methyltriphenylphosphonium) hexabromidoselenate(IV)-bis{dibromidoselenate(II)},[PMePh3]2[SeBr6(SeBr2)2], received by direct synthesis and two mixed-valence bromidochalcogenates(IV/II) – bis(methyltriphenylphosphonium) and bis(tetrapropylammonium) hexabromidotellurates(IV)-selenates(II), [PMePh3]2[TeBr6(SeBr2)2] and [NnPr4]2[TeBr6(SeBr2)2], were synthesized from elemental selenium, tellurium dioxide, and corresponding onium bromide. The structures of all compounds were determined by X-ray diffraction.

Several hydroxyl- and ether-functionalized binary task specific ionic liquids (ILs) are prepared, ether-functionalized ILs exhibit higher conductivity and lower viscosity than those of hydroxyl-functionalized ILs, whereas hydroxyl-functionalized ILs show wider potential window than those of ether-functionalized ILs. The correlation between ionic conductivity and viscosity is based on the classical Walden rule; a relatively large deviation of the plots from the ideal Walden line is observed for the ILs without considering the ion size, whereas the deviation decreases significantly when the adjusted Walden plot is adopted. The α values of ILs calculated from the slopes of the Walden plots are compared to those calculated from the ratio of activation energies for viscosity and molar conductivity (Ea,Λ/Ea,η). There are very few reports where electrochemically derived activation energy from conductivity and voltammetric characterization are available for comparison, so a key concept of activation energy in electrochemistry could be developed in this paper.

A new method has been developed for preparing acid onium salts of Keggin heteropolyacids via ion exchange on amorphous silica functionalized with pyridinium and alkylimidazolium cations (SiO 2 –Q). The interaction between HPA and the surface-grafted cations affords acid salts of HPA with intact Keggin structure. This method offers excellent dispersion of HPA on the surface and higher resistance to HPA leaching in polar media, compared to the silica-based materials. The solids are thermally stable up to 250–300 °C, depending on the onium cation and anion, the most stable being the samples with immobilized H 4 SiW 12 O 4 and H 3 PW 12 O 40 .

Structural features, the crystal packing, and the proton conductivity of a series of hydrates and ammonium salts of 4-nitrobenzenesulfonic acid were studied. It was shown that infinite cation associates containing the onium moiety are responsible for a substantial increase in the proton conductivity. The nature of the disorder in a series of crystals was investigated by performing X-ray diffraction studies at different temperatures. A new type of structural synthons, viz., anion-anion dimers stabilized by the SO3 −…NO2 interaction, was found and characterized and the role of solvent water molecules was elucidated based on high-resolution X-ray diffraction data. The water molecules serve mainly as channels for charge transfer from the cation to the anion with retention of the electroneutrality.

The kinetics and products of the thermal decomposition of hexamethylenetetraammonium dodecahydro-closo-dodecaborate in air, argon, and a vacuum were studied using thermogravimetry, volumetry, mass spectrometry, and IR spectroscopy. According to the nonisothermal kinetic data, noticeable rates of the formation of volatile products were observed at temperatures higher than 150°C. The thermal decomposition of the salt occurred in stages. At 160–200°C, the thermal decomposition of hexamethylenetetraammonium dodecahydro-closo-dodecaborate could not be described by simple kinetic equations. The dependence of the initial reaction rates on inverse temperature (lnV0−1/K) was linear, which showed that the thermal decomposition of the salt obeyed the Arrhenius equation V0 = 109.4 ± 0.6exp[(−20500 ± 1800)/RT], %/min. The obtained temperature dependences of the kinetic parameters of thermolysis were used to predict the time of salt storage and the conditions of work with it. A comparison of the kinetics of the thermolysis of hexamethylenetetraammonium dodecahydro-closo-dodecaborate and free hexamethylenetetraamine in open and closed reaction systems showed that the thermolysis of hexamethylenetetraammonium dodecahydro-closo-dodecaborate was not accompanied by salt dissociation to hexamethylenetetraamine and dodecahydro-closo-dodecaborate acid. The products of its thermolysis volatile under normal conditions were trimethylamine with a small admixture of nitrogen. The solid residue after thermolysis was a high-porosity insoluble product, whose volume was 6–8 times larger than the volume of the initial sample. An analysis of the IR spectra of the solid thermolysis product showed that it had a well-defined salt character. The special features of the IR spectra of initial hexamethylenetetraammonium dodecahydro-closo-dodecaborate and the product of its thermolysis led us to suggest that an acid-base equilibrium of the type [R3N-H+] + A ↔ [R3N… H+…A] occurred in it and, probably, in the initial salt. Here, R3N is the tertiary amino group, and A is the borohydride acid residue. Indications of amorphization allowed us to suggest that polymer structures were formed as a result of intramolecular interaction between the borohydride anion and onium cation.