Oxalate Anions Research Articles

Single-Ion Magnet and Photoluminescence Properties of Lanthanide(III) Coordination Polymers Based on Pyrimidine-4,6-Dicarboxylate

Herein, we report the magnetic and photoluminescence characterization of coordination polymers (CP) built from the combination of lanthanide(III) ions, pyrimidine-4,6-dicarboxylate (pmdc) ligand and a co-ligand with formula {[Dy(μ-pmdc)(μ-ox)0.5(H2O)3]·2H2O}n (1-Dy), {[Dy(μ3-pmdc)(μ-ox)0.5(H2O)2] ~2.33H2O}n (2-Dy), {[Dy2(μ3-pmdc)(μ4-pmdc)(μ-ox)(H2O)3]·5H2O}n (3-Dy), {[Ln(μ3-pmdc)(μ-ox)0.5(H2O)2]·H2O}n (where Ln(III) = Nd (4-Nd), Sm (4-Sm), Eu (4-Eu) and Dy (4-Dy)) and {[Dy(μ4-pmdc)(NO3)(H2O)]·H2O}n (5-Dy). It must be noted the presence of oxalate anion acting as ditopic co-ligand in compounds 1-Dy, 2-Dy, 3-Dy and 4-Ln, whereas in 5-Dy the nitrate anion plays the role of terminal co-ligand. Direct current measurements carried out for the dysprosium-based CPs reveal almost negligible interactions between Dy3+ ions within the crystal structure, which is confirmed by computed values of the exchange parameters J. In addition, alternating current measurements show field-induced single-molecule magnet (SMM) behavior in compounds 1-Dy, 2-Dy, 4-Dy and 5-Dy, whereas slight-frequency dependence is also observed in 3-Dy. Solid state emission spectra performed at room temperature for those compounds emitting in visible region confirm the occurrence of significant ligand-to-lanthanide charge transfer in view of the strong characteristic emissions for all lanthanide ions. Emission decay curves were also recorded to estimate the emission lifetimes for the reported compounds, in addition to the absolute quantum yields. Among them, the high quantum yield of 25.0% measured for 4-Eu is to be highlighted as a representative example of the good emissive properties of the materials.

Observation of pressure-induced electron transfer in SnC2O4.

We examined the high pressure behavior of stannous oxalate via Raman and X-ray absorption spectroscopy (XAS) inside a diamond anvil cell. Phase transitions were observed to occur near 2.6 and 15 GPa which were reversible upon decompression to ambient conditions. When further pressurized above 15 GPa, the colorless material sustains irreversible chemical alterations and becomes bright red colored - darkening at higher pressures. Another irreversible phase transition occurred above 20 GPa. Concomitant with color change of the sample, we observed a softening of the ν(C-C) modes of the C2O42- anion via Raman spectroscopy. We performed a separate XAS experiment which indicates that the Sn2+ cation undergoes a partial reduction of the 2+ oxidation state with pressure which persists when the sample was depressurized to ambient conditions. Thus, electron density within the C-C bond in the oxalate anion appears to migrate toward the tin cation with pressure. This observation suggests that pressure can offer a very controllable means to vary cation-anion and unit cell dimensions (and thus the electric interactions causing electron movement) and thus the pressure-induced synthesis of novel materials.

Mg-Cr Layered Double Hydroxide Intercalated Oxalic Anion to Remove Cationic Dye Solutions: Rhodamine B and Methylene Blue

A MgCr-based layered double hydroxide (LDH) was synthesized by a coprecipitation method, followed by an intercalation process using an oxalic anion. The materials were characterized using X-ray diffraction analysis, FT-IR spectroscopy, and pH pzc measurement. The materials were then applied as adsorbents for removal of methylene blue (MB) and rhodamine B (RhB) from aqueous solution. Pristine Mg/Cr LDH exhibited RhB adsorption capacity of 32.154 mg g⁻1, whereas the use of intercalated Mg/Cr LDH caused an increase in the capacity (139.526 mg g⁻1). Kinetic studies indicated that the dye adsorption using both LDHs followed a pseudo-second-order kinetic model; the K2 values of pristine and modified Mg/Cr LDH for RhB and MB were 6.970, 0.001, 0.426, and 2.056 g mg⁻1 min⁻1, respectively. The thermodynamic study identified that the adsorption of both dyes onto the LDHs was a spontaneous process and can be classified as physical adsorption with adsorption energies of <40 kJ/mol. Moreover, the desorption and regeneration experiments indicated the high economic feasibility and reusability of the LDHs. By using HCl as the optimal solvent, the LDHs could desorb as much as 98% of the dye and could be used as adsorbents with high adsorption capacity over three cycles.

Mg-Cr Layered Double Hydroxide with Intercalated Oxalic Anion for Removal Cationic Dyes Rhodamine B and Methylene Blue

A MgCr-based layered double hydroxide (LDH) was synthesized by a coprecipitation method, followed by an intercalation process using an oxalic anion. The materials were characterized using X-ray diffraction analysis, FT-IR spectroscopy, and pH pzc measurement. The materials were then applied as adsorbents for removal of methylene blue (MB) and rhodamine B (RhB) from aqueous solution. Pristine Mg/Cr LDH exhibited RhB adsorption capacity of 32.154 mg g⁻1, whereas the use of intercalated Mg/Cr LDH caused an increase in the capacity (139.526 mg g⁻1). Kinetic studies indicated that the dye adsorption using both LDHs followed a pseudo-second-order kinetic model; the K2 values of pristine and modified Mg/Cr LDH for RhB and MB were 6.970, 0.001, 0.426, and 2.056 g mg⁻1 min⁻1, respectively. The thermodynamic study identified that the adsorption of both dyes onto the LDHs was a spontaneous process and can be classified as physical adsorption with adsorption energies of <40 kJ/mol. Moreover, the desorption and regeneration experiments indicated the high economic feasibility and reusability of the LDHs. By using HCl as the optimal solvent, the LDHs could desorb as much as 98% of the dye and could be used as adsorbents with high adsorption capacity over three cycles.

Comparison of Oxalate, Citrate and Tartrate Ions Adsorption in the Hydroxyapatite/Aqueous Electrolyte Solution System

The kinetics of adsorption/desorption of oxalate, citrate and tartrate anions was investigated using hydroxyapatite from solutions at the initial concentrations of 0.000001 and 0.001 mol/dm3 anions. The adsorption process from a solution with a concentration of 0.001 mol/dm3 takes place in three stages and is well described by the multiexponential equation of adsorption kinetics. The process of tartrate and citrate ion desorption after increasing the pH to 10 is irreversible, while the oxalate ions undergo significant desorption with the increasing pH. The adsorption of oxalate ions decreases with the increasing pH. This effect is weaker in the adsorption of citrate and tartrate ions. Ion adsorption studies were supplemented with the measurements of zeta potential, FTIR and particle distribution of hydroxyapatite particles.

Термическое разложение двойных комплексных соединений 3d-металлов.

The paper is devoted to the study of thermolysis of double complex compounds (DCС) of metalsin the I transition series. 30 DCСwith various combinations of metal-central atoms (Co-Fe, Cu-Fe, Ni-Fe Cr-Fe, Cr-Co,) and ligands (ammonia, urea (ur), ethylenediamine (en), 1,3-diaminopropane (tn), cyanide, oxalate and nitrite anions) were synthesized and characterized. A complete study of the thermal proper-ties of these DCCs in three atmospheres was carried out: oxidizing (air), inert (Ar, N2, partly He) and re-ducing (H2), in the temperature range of 20–1000°Cand at constant heating rate of 10°C/min. The solid and gaseous thermolysis products were studied. In the air solid thermolysis products are represented by mixtures of central ions oxides or mixed oxides of the MIMII2O4type. The main gaseous products of thermolysis underthe temperature below 300°Cinclude NH3, HNCO (for urea DCС) and HCN (for cya-nocomplexes), and above 300°C —СО2. In addition, undecomposed ligands, CO, nitrogen oxides and probably nitrogen are presented in the gas phase. Thermolysis of the studied DCCgoesin the most com-plex way in inert atmospheres. Solid thermolysis products are heterogeneous mixtures of metals (Cu, Fe), solid solutions of CoxFe1-x, Ni3Fe intermetallic compounds, oxides, carbides and nitrides of central ions and amorphous carbon; the content of the latter reaches 58% of the initial content in the complex. The gaseous products of thermolysis include the same compounds, except for CO2, as in the atmosphere of air, but also in different ratios. In an H2atmosphere, all studied DCCs, except Cr-containing ones, are re-duced to the sum of central ions —Cu + Fe or solid solutions Co-Fe and Ni-Fe, practically free of carbon. Gaseous products are the same as in an inert atmosphere, butan increased yield of NH3and a reduced yield of CO2and/or HCN speak in favor of partial hydrogenation of the ligands to hydrocarbons. A review of the catalytic properties of solid products of DCC thermolysis (~170 samples) showed that about 1/3 of themare active in model reactions (catalytic decomposition of hydrogen peroxide, thermal decomposi-tion of ammonium perchlorate).

New chromium(III)-based catalysts for ethylene oligomerization

The report focuses on the new precatalysts for ethylene oligomerization. The five chromium(III) complex compounds containing the following ligands: dipicolinate anion, oxalate anion, 5-aminopyridine-2-carboxylate anion, 2,2′-bipyridine and 4,4′-dimethoxy-2,2′-bipyridine have been examined towards catalytic activity for ethylene oligomerization. The chromium(III) complexes have been activated by modified methylaluminoxane. The obtained oligomers have been investigated by MALDI-TOF–MS, thermal analysis and infrared spectroscopy. The results revealed that the examined chromium(III) complexes are highly active catalysts for ethylene oligomerization. The values of catalytic activities of the examined complexes are in the range 1860 – 3798 g∙mmol-1∙h-1∙bar-1.

Preparation of novel chemically bonded ceramics with steel slag and potassium hydrogen oxalate

A novel chemically bonded ceramic (novel-CBC) is prepared based on the acid–base reaction of alkali metals in steel slag (SS) and oxalate anion (C2O42−) in potassium hydrogen oxalate (PO). The effects of SS/PO ratio and water–solid (W/S) ratio on the setting and compressive strength of novel-CBC were studied in this paper. Reaction products and microstructure of novel-CBC were characterized by X-ray diffractometer (XRD), field emission scanning electron microscope-energy dispersive spectroscopy (FESEM-EDS) and thermogravimetric analysis/differential scanning calorimetry (TG/DSC). An optimal formula is obtained at a SS/PO ratio of 3.0 and a W/S ratio of 0.20, which starts setting at 10 min and gives the strengths of 18.0, 25.0, 39.8 and 49.0 MPa at 1, 3, 7 and 28 days, respectively. The reactants from SS are mainly Ca-bearing phases, while only a small amount of RO phase is involved in reaction. The main reaction products of novel-CBC are calcium oxalate monohydrate (CaC2O4·H2O; whewellite) crystals and agglomerates consisting of K, Mg, Al, Si and O elements. The unreacted Ca-bearing phase particle and RO phase residue are embedded in a mixture of abundant CaC2O4·H2O crystals with smooth surfaces and a size of 0.5–1.0 µm with large amounts of the nanoscale agglomerates.

Selective capture of carbon dioxide from humid gases over a wide temperature range using a robust metal–organic framework

Physisorption presents as a promising energy-saving technique for carbon dioxide (CO2) sequestration, which is crucial for processing various industrially important gases (e.g. natural gas and flue gas). However, to target desirable porous materials that simultaneously combine high CO2 selectivity and moderate adsorption enthalpy especially under humid and wide-temperature environment is challenging. Herein, we report the capture of CO2 from humid gas with a novel ultramicroporous metal–organic framework ZU-301 that features one-dimensional robust pore channel decorated by high-density oxalate anions and hydrophobic methyls. The rigid framework coupled with fine-tuned aperture size permits CO2 trapping while sets a barrier for CH4, leading to excellent separation selectivity (90–111) in a wide temperature range (298–323 K). The introduced oxalate anions and methyls synergistically grasp CO2via mild interactions, giving rise to moderate adsorption enthalpy (38 kJ mol−1), as evidenced by single-crystal X-ray diffraction analysis performed on CO2-loaded ZU-301, meanwhile render ZU-301 low affinity to moisture with the CO2/H2O uptake ratio outperforming many benchmark materials. Additionally, ZU-301 exhibits good chemical stability, which even can be soaked in strong acid or base solutions (pH = 2–12) without losing CO2 capture ability. Breakthrough experiments confirmed the high efficiency of ZU-301 for CO2/CH4 and CO2/N2 separation under elevated temperature and humid conditions, which is of important scientific and industrial value.

Oxalate‐fluoride anion exchange in alpine tundra soil: Impact on aluminium transport

AbstractAnion exchange between ubiquitous low‐molecular‐weight organic acids (LMWOA), such as oxalate, and surface‐retained inorganic anions, such as F−, SO42− and OH−, can play a critical role in Al bioavailability and transport in acidic alpine tundra soil. A series of batch equilibration and composite soil column leaching studies were conducted to examine anion exchange reactions between F−, oxalate and OH−, and the impact of increased soil solution F− concentration on Al transport. The addition of either F− or oxalate to soil suspensions resulted in significantly higher solution pH, suggesting F− and oxalate exchange with surface –OH groups. Distinct stages of OH− release were observed for all soil horizons leached with 1.32 × 10−3 mol l−1 F−, with OH− release decreasing in the order O/A1 ~ A2> > Bw. A similar OH− release pattern was observed in the O/A1 horizon for the 7.81 × 10−4 mol l−1 oxalate treatment, suggesting that both F− and oxalate may be competing for common exchange sites in the O/A1 horizon. Fluoride displacement by oxalate, in batch equilibration experiments, was observed for both the 2.84 × 10−4 mol l−1 and 7.81 × 10−4 mol l−1 oxalate treatment. Individual soil horizons leached with 7.81 × 10−4 mol l−1 oxalate exhibited increased F− leaching in the order O/A1 > A2 ~ Bw, with pulsed F− movement being observed in the O/A1 horizon. Soil columns eluted with 1.32 × 10−3 mol l−1 F− exhibited increased Al solubilization and transport, with Al leaching increasing in the order Bw > A2 > O/A1. Sequential leaching of soil columns in the order D. I. H2O → 1.32 × 10−3 mol l−1 F− → D.I. H2O → 7.81 × 10−4 mol l−1 oxalate indicated that previously adsorbed F− was displaced by oxalate. Displacement of F− by oxalate increased in the order O/A1 > A2 > Bw. Hydroxyl displacement by both F− and oxalate may be an important source of acid neutralization in a soil wetting front, affecting Al speciation and transport.Highlights Oxalate and F− compete for similar OH− exchange sites, increasing soil pH. Adsorbed F− can be displaced by oxalate anions. Al solubilization increases with F− adsorption in alpine tundra soil. Aluminium fluoride speciation changes rapidly within the soil wetting front. Anion exchange reactions should be considered in assessing soil ANC.

Model Dimeric Manganese(IV) Complexes Featuring Terminal Tris-hydroxotetraazaadamantane and Various Bridging Ligands.

A series of model dinuclear manganese(IV) complexes of the general formula [(H3COH)(L')MnIV(μ-L)2MnIV(L')(HOCH3)] is presented. These compounds feature capping 4,6,10-trihydroxo-3,5,7-trimethyl-1,4,6,10-tetraazaadamantane ligands derived from a polydentate oxime compound (L'). The bridging ligands L include azide (1), methoxide (2), and oxalate (3) anions. The magnetic properties and high-field (HF) EPR spectra of 1-3 were studied in detail and revealed varying weak antiferromagnetic coupling and modest zero-field splitting (ZFS) of the local quartet spin sites. Our HF EPR studies provide insight into the dimer ZFS, including determination of the corresponding parameters by giant spin approach for methoxido-bridged complex 2. Furthermore, the physicochemical properties of 1-3 were studied using IR, UV-vis, and electrochemical (cyclic voltammetry) methods. Theoretical exchange coupling constants were obtained using broken-symmetry (BS) density functional theory (DFT). Computational estimates of the local quartet ground spins state ZFSs of 1-3 were obtained using coupled-perturbed (CP) DFT and complete active space self-consistent field (CASSCF) calculations with n-electron valence state perturbation theory (NEVPT2) corrections. We found that the CP DFT calculations which used the B3LYP functional and models derived experimental structures performed best in reproducing both the magnitude and the sign of the experimental D values. Moreover, our computational investigation of 1-3 suggests that we observe metals sites which have an increased +3 character and are supported by redox noninnocent 4,6,10-trihydroxo-3,5,7-trimethyl-1,4,6,10-tetraazaadamantane ligands. The latter conclusion is further corroborated by the observation that the free ligand can be readily oxidized to yield a NO-based radical.

Doubly mononuclear cocrystal and oxalato-bridged binuclear copper compounds containing flexible 2-((3,5,6-trichloropyridin-2-yl)oxy)acetate tectons: Synthesis, crystal analysis and magnetic properties

Two new copper compounds, namely [Cu(3,5,6-tcpa)2(H2O)4]·[Cu(3,5,6-tcpa)2(H2O)2] (1) and [Cu2(3,5,6-tcpa)2(2,2′-bipy)2(oxa)]·2EtOH (2) (3,5,6-Htcpa = 2-((3,5,6-trichloro pyridin-2-yl)oxy)acetic acid, 2,2′-bipy = 2,2′-bipyridine, oxa = oxalate dianion), have been synthesized by solvothermal method and systematically characterized. Single-crystal X-ray diffraction analysis show that 1 is an interesting double mononuclear cocrystal and consists of two discrete and stereochemically different complexes: one octahedral, the other tetrahedral about the copper centres. While for 2, two equivalent copper ions are in square pyramidal geometry and linked by oxalate anion forming a novel binuclear cluster. The OH···O hydrogen bonds, Cl···Cl halogen bonds and/or π···π stacking interactions play an important part in construction of the 3D networks for 1 and 2. The magnetic measurements indicate that there is weak antiferromagnetic coupling between two copper ions in 1 and 2. Notably, compound 2 also can be obtained in a higher yield with 1 as one of the starting material and the driving force for this transition process have been carefully discussed.

Study on the Electrodeposition of Chromium from Cr(III) Solution in the Presence of Oxalate and Acetate Anions

Study on the Electrodeposition of Chromium from Cr(III) Solution in the Presence of Oxalate and Acetate Anions

Study on the Electrodeposition of Trivalent Chromium Plating Bath in the Presence of Oxalate Anions

Chromium is not easily electrodeposited from aqueous solutions based on trivalent chromium. Hull cell is employed to determine the optimum bath composition, and several electroplating baths were evaluated. The new bath with oxalate and acetate anions produces very good coatings and our results are valuable for the electroplating community and electrochemists. The baths presented a current efficiency of 37%, high covering power at 8.2 cm, low deposition potential of 7.3 V, and deposition rate of 0.4 μm/min. However, the Hull cell required a high current density (30 A/dm2). After 2 h of the electrodeposition process, the pH values change by 0.2 units. In addition, the baths were analyzed after electrolysis to detect Cr(VI), and this cation was not detected. Our study not only has a technological contribution but also presents a new explanation for the nature of these baths. In the literature, the usual explanation of the performance of these baths is based on the formation of complexes between ligands and Cr(III); however, our novel explanation is based on the high stability of water in the first solvation sphere of Cr(III), and we support our suggestions with several references to chromium solvation studies. The ligand-exchange reaction explanation is replaced by the second sphere hypothesis, that is, our explanation is based on the large stabilization energy of Cr−O bonds in [Cr(H2O)6]3+. Figure 1

Photosynergetic Electrochemical Synthesis of Graphene Oxide.

Here we propose a strategy of radical oxidation reaction for the high-efficiency production of graphene oxide (GO). GO plays important roles in the sustainable development of energy and the environment, taking advantages of oxygen-containing functional groups for good dispersibility and assembly. Compared with Hummers' method, electrochemical exfoliation of graphite is considered facile and green, although the oxidation is fairly low. To synthesize GO with better crystallinity and higher oxidation degree, we present a photosynergetic electrochemical method. By using oxalate anions as the intercalation ions and co-reactant, the interfacial concentration of hydroxyl radicals generated during electrochemical exfoliation was promoted, and the oxidation degree was comparable with that of GO prepared by Hummers' method. In addition, the crystallinity was improved with fewer layers and larger size. Moreover, the aniline coassembled GO membrane was selectively permeable to water molecules by the hydrogen-bond interaction, but it was impermeable to Na+, K+, and Mg2+, due to the electrostatic interactions. Thus, it has a prospective application to water desalination and purification. This work opens a novel approach to the direct functionalization of graphene during the electroexfoliation processes and to the subsequent assembly of the functionalized graphene.

Photoinduced Fenton-simulated reduction system based on iron cycle and carbon dioxide radicals production for rapid removal of Cr(VI) from wastewater

For the harmless treatment of oxoanions, reduction approach is thought to be ideal. In this study, a Fenton mode-simulated advanced reduction system was conceived to directly produce highly reductive radical for the rapid removal of high concentration Cr(VI). Oxalate anions could be induced by Fe3+ under light excitation to generate reductive carbon dioxide anion radicals (CO2•-) and Fe2+. Both species could reduce Cr(VI), wherein CO2•- would produce environmentally friendly CO2 while Fe2+ is converted into Fe3+ for next catalytic cycle. Factor tests suggested that the concentration of Fe3+ and oxalate mainly determined the reduction rate and capacity of Cr(VI) respectively. The reduction efficiency could reach almost 100% even within 5 min at 1.0 mM Cr(VI) concentration. The molar ratio of reduced Cr(VI) over provided oxalate always maintained at about 0.35–0.4. More importantly, this system could operate at natural light with a respectable kinetic rate and degrade dye synchronously in Cr(VI) reduction. Furthermore, the continuous treatment of Cr(VI) was achieved through simply adding oxalate. The mechanism was confirmed by electron spin resonance (EPR) experiment and dissolved oxygen was revealed to participate reaction pathway. This system is economical, easy operated and efficient, showing a great practical application potential on oxoanions removal from wastewater.

H-bond catalytic mechanism of aromatic electrophilic substitution between phenol and formaldehyde

Phenolic resins are widely used as moulding plastics, coatings, industrial bondings and ablative materials. An essential reaction step for preparing phenolic resins is aromatic electrophilic substitution. However, the current understanding of this reaction mechanism is kind of too general, making them not able to explain some phenomena such as highly exothermic characteristic of the early reaction stage between phenol and aldehyde under acid catalysis, and how attacking species form when the reaction begins. We studied the detailed catalytic mechanism by quantum mechanics. A new hydrogen-bond (H-bond) catalytic mechanism is suggested. It reveals that the essence of the acid catalytic mechanism is electrophile activation through hydrogen-bonding, and the substrate-catalyst complex formed through an H-bond is the attacking species. Besides, the study discloses that oxalate anion takes part in the reaction through bonding with arenium ion. The thermodynamic and kinetic characters based on this mechanism are quite different from the current theories.

Crystal structure and Hirshfeld surface analysis of 1,2,4-triazolium hydrogen oxalate.

The asymmetric unit of the title 1:1 salt 1,2,4-triazolium hydrogen oxalate, C2H4N3 +·C2HO4 - (I), comprises one 1,2,4-triazolium cation and one hydrogen oxalate anion. In the crystal, the hydrogen oxalate anions are linked by O-H⋯O hydrogen bonds into chains running parallel to [100]. In turn, the anionic chains are linked through the 1,2,4-triazolium cations by charge-assisted +N-H⋯O- hydrogen bonds into sheets aligned parallel to (01). The sheets are further stacked through π-π inter-actions between the 1,2,4-triazolium rings [centroid-to-centroid distance = 3.642 (3) Å, normal distance = 3.225 (3) Å, slippage 1.691 Å], resulting in the formation of a three-dimensional supra-molecular network. Hirshfeld surface analysis of the title salt suggests that the most significant contributions to the crystal packing are by H⋯O/O⋯H and H⋯N/N⋯H contacts involving the hydrogen bonds.

Co-crystallization of Oxalate Salts of Monoprotonated Amines with a Double Sn-Ph Bond Cleavage

Two oxalate compounds [(C4H7N2)3][Sb(C2O4)3] (1) and [(Et3NH)][SnPhCl(C2O4)2] (2), have been isolated and characterized by single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic system, space group P21/c with a=13.3944 (6) A, b=11.3554 (5) A, c=16.3314 (7) A, β=107.206 (1), V=2372.82 (18) A3 and Z=4. Compound 2 crystallizes in the monoclinic system, space group P21/n with a=8.6903 (4) A, b=15.3844 (8) A, c=20.3144 (10) A, β=100.869 (2), V=2667.2 (2) A3 and Z=4. The complex-anion [Sb(O2CCO2)3]3- of the compound 1 adopts a distorted pentagonal pyramidal arrangement with monochelating oxalates. The asymmetric unit of 1 consists of three 2-methyl-1H-imidazolium cations, C4H7N2+, three oxalate anions, C2O42-, and one antimony (III) ion, Sb3+. From a supramolecular point of view, in 1 complex-anions are connected by cations through N-H•••(O,O) and N-H•••O hydrogen bonds involving the two oxalates of the basal plane into sheets which are then connected via the remaining oxalate and cations through N-H•••O hydrogen bonds to give rise to a three-dimensional structure. The complex-anion of 2 is comprised of a tin centre linked to a chlorine atom and a phenyl group, and cis-chelated by two oxalates in a distorted octahedral fashion. Each triethylammonium cation is connected to the complex-anion through bifurcated N-H•••(O,O) hydrogen bonds. These interactions lead to a discrete structure. A double Sn-C bond cleavage has occurred during the process of the formation of the compound 2. In both complounds 1 and 2, one cation exhibits some positional disorder.

Structural and spectroscopic aspects on anilinium hydrogen oxalate hemiihydrate

In the present communication, aniline with oxalic acid molecular complex (C6H5NH3+.C2HO4-.0.5H20) has been taken as the subject. The anilinium oxalate hemihydrate – a new crystalline product have been grown by slow evaporation technique at room temperature. Single crystal X-ray diffraction study reveals that the grown crystal crystallizes in monoclinic system with centro symmetric space group C2/c with primitives.a = 24.004(5)Å, b = 5.7500(10)Å, c = 13.890(3) Å and interfacial angles α = γ = 90° and β = 109.29(3)o. The strong hydrogen bond interactions between the singly protonated anilinium cation and single dissociated oxalate (1-) anions forms a three dimensional network. The crystallite size is calculated to be 17.355 μm using Debye-Scherrer’s formula. Room temperature powder infrared and Raman measurements for the aniline oxalate molecular complex (1:1) were carried out. The FT-IR and FT Raman spectra have been recorded and various vibrations of aniline as well as oxalate ions present in the grown crystal is identified and discussed in detail. Further the 3D Hirshfeld surface analysis and 2D fingerprint maps gives deep insight into the intermolecular interactions between the compound.