NMR and EPR studies of the reaction of nucleophilic addition of (bi)sulfite to the nitrone spin trap DMPO

The reaction of the nitrone spin trap 5,5‐dimethylpyrroline‐N‐oxide (DMPO) with sodium (bi)sulfite in aqueous solutions was investigated using NMR and EPR techniques. Reversible nucleophilic addition of (bi)sulfite anions to the double bond of DMPO was observed, resulting in the formation of the hydroxylamine derivative 1‐hydroxy‐5,5‐dimethylpyrrolidine‐2‐sulfonic acid, with characteristic ¹H and ¹³C NMR spectra. The reaction mechanism was suggested and corresponding equilibrium constants determined. The mild oxidation of the hydroxylamine results in the formation of an EPR‐detected spectrum identical with that for the DMPO adduct with sulfur trioxide anion radical. The latter demonstrates that a non‐radical addition reaction of (bi)sulfite with DMPO may contribute to the EPR detection of SO₃^?? radical. This possibility must be taken into account in spin trapping analysis of sulfite radical. Copyright © 2003 John Wiley & Sons, Ltd.     

Reversible SO2 Uptake by Tetraalkylammonium Halides: Energetics and Structural Aspects of Adduct Formation Between SO2 and Halide Ions

Contact with SO₂ causes almost immediate dissolution of tetraalkylammonium halides, R₄NX, (R = CH₃ (Me), X = I; R = C₂H₅ (Et), X = Cl, Br, I; R = C₄H₉ (nBu), X = Cl, Br), with the formation of an adduct, [R₄N]⁺[(SO₂)_nX]^– (n = 1–4). Vapor pressure measurements indicate the proclivity for SO₂ uptake follows the order N(CH₃)₄⁺ < N(C₂H₅)₄⁺ < N(C₄H₉)₄⁺. This trend is in accord with the Jenkins–Passmore volume‐based thermodynamic model. Born–Haber cycles, incorporating the lattice energy and gas phase energy terms, are used to evaluate the energetic feasibility of reactions. Density functional theory calculations (B3PW91; 6‐311+G(3df)) have been used to calculate the energetics of (SO₂)_nX^– (X = Cl and Br) anions in the gas phase. The experimental studies show that tetraalkylammonium halides are feasible sorbents for SO₂. In order to correlate the theoretical model, experimental enthalpy, Δ_rH° and entropy, Δ_rS° changes have been determined by the van't Hoff method for the binding of one SO₂ molecule to (C₂H₅)₄NCl, resulting in the liquid adduct (C₂H₅)₄NCl · SO₂. The structure of the analogous 1:1 bromide adduct, (C₂H₅)₄NBr · SO₂, has been determined by single‐crystal X‐ray diffraction (monoclinic, P2₁/c, a = 9.1409(14) Å, b = 12.3790(19) Å, c = 11.3851(17) Å, β = 107.952(2)°, V = 1225.6(3) ų). The structure consists of discrete alkylammonium cations, bromide anions and SO₂ molecules with short contacts between the anion and SO₂ molecules. The (C₂H₅)₄N⁺ cationadopts a transoid conformation with D_2d symmetry, and represents a rare example of a well‐ordered (C₂H₅)₄N⁺ cation in a crystal structure. The Br^– anions and SO₂ molecules forms a chain, (SO₂Br^–)_n, with bifurcated contacts. Non‐bonding electron pairs on the halide anions engage in electrostatic interactions with the sulfur atoms and charge‐transfer interactions with the antibonding S–O orbitals of the bound SO₂ moiety. Raman and ¹⁷O NMR spectra provide compelling evidence for a charge‐transfer interaction between SO₂ molecules and the halide ions.     

Complete experimental and theoretical proton and carbon nuclear magnetic resonance spectral assignments,molecular structure and conformational study of 1‐cyclohexylpiperazine and 1‐(4‐pyridyl)piperazine

The possible stable forms and molecular structures of 1‐cyclohexylpiperazine (1‐chpp) and 1‐(4‐pyridyl)piperazine (1‐4pypp) molecules have been studied experimentally and theoretically using nuclear magnetic resonance(NMR) spectroscopy. ¹³C, ¹⁵N cross‐polarization magic‐angle spinning NMR and liquid phase¹H, ¹³C, DEPT, COSY, HETCOR and INADEQUATE NMR spectra of 1‐chpp (C₁₀H₂₀N₂) and 1‐4pypp (C₉H₁₃N₂) have been reported. Solvent effects on nuclear magnetic shielding tensors have been investigated using CDCl₃, CD₃ OD, dimethylsulfoxide (DMSO)‐d₆, (CD₃)₂CO, D₂O and CD₂Cl₂. ¹H and ¹³C NMR chemical shifts have been calculated for the most stable two conformers, equatorial–equatorial (e–e) and axial–equatorial (a–e) forms of 1‐chpp and 1‐4pypp using B3LYP/6‐311++G(d,p)//6‐31G(d) level of theory. Results from experimental and theoretical data showed that the molecular geometry and the mole fractions of stable conformers of both molecules are solvent dependent. Copyright © 2009 John Wiley & Sons, Ltd.     

Darstellung von Tetramethylammoniumazidsulfit und Tetramethylammoniumcyanat‐Schwefeldioxid‐Addukt, [(CH3)4N]+[SO2N3]–, [(CH3)4N]+ [SO2OCN]– und Kristallstruktur von [(CH3)4N]+[SO2N3]–

Preparation of Tetramethylammonium Azidosulfite and Tetramethylammonium Cyanate Sulfur Dioxide‐Adduct, [(CH₃)₄N]⁺[SO₂N₃]^–, [(CH₃)₄N]⁺[SO₂OCN]^– and Crystal Structure of [(CH₃)₄N]⁺[SO₂N₃]^– Tetramethylammonium azide forms with sulfur dioxide an azidosulfite salt. It is characterized by NMR and vibrational spectroscopy and the crystal structure analysis. [(CH₃)₄N]⁺[SO₂N₃]^– crystallizes in the monoclinic space group P2₁/c with a = 551.3(1) pm, b = 1095.2(1) pm, c = 1465.0(1) pm, β = 100.63(1)°, and four formula units in the unit cell. The crystal structure possesses a strong S–N interaction between the N^3– anions and the SO₂ molecules. The S–N distance of 200.5(2) pm is longer than a covalent single S–N bond. The structure is compared with ab initio calculated data. Furthermore an adduct of tetrametylammonium cyanate and sulfur dioxide is reported. It is characterised by NMR and vibrational spectroscopy. The structure is calculated by ab initio methods.     

Synthesis,Characterization, and Luminescent Properties of Silver(I) Complexes based on Diphosphine Ligands and 2,9‐Dimethyl‐1,10‐phenanthroline

Five mono‐nuclear silver(I) complexes with the ligand 2,9‐dimethyl‐1,10‐phenanthroline, namely [Ag(DPEphos)(dmp)]BF₄ ( 1 ), [Ag(DPEphos)(dmp)]CF₃SO₃ ( 2 ), [Ag(DPEphos)(dmp)]ClO₄ ( 3 ), [Ag(DPEphos)(dmp)]NO₃ ( 4 ), and [Ag(dppb)(dmp)]NO₃ · CH₃OH ( 5 ) {DPEphos = bis[2‐(diphenylphosphanyl)phenyl]ether, dppb = 1,2‐bis(diphenylphosphanyl)benzene, dmp = 2,9‐dimethyl‐1,10‐phenanthroline} were characterized by X‐ray diffraction, IR, ¹H NMR, ³¹P NMR and fluorescence spectroscopy. Their terahertz (THz) time‐domain spectra were also studied. In these complexes the silver(I), which is coordinated by two kinds of chelating ligands, adopts four‐coordinate modes to generate mono‐nuclear structures. In complexes 1 , 3 – 5 , offset π ··· π weak interactions exist between the neighboring benzene rings. In the ³¹P NMR spectra, there exist splitting signals (dd), which can be attributed to the coupling of the ^107,109Ag–³¹P. All the emission peaks of these complexes are attributed to ligand‐centered excited states.     

High-field NMR of ethylene—sulfur dioxide copolymers

Copolymers of ethylene and sulfur dioxide containing 40–60 wt-% sulfur dioxide have been analyzed by using 220 MHz high-resolution NMR, and it has been shown that they contain structures of the form, ? SO₂? (CH₂? CH₂)_n? SO₂? , where n is 1, 2, 3, 4, … The relative numbers of structures with n = 1, 2, 3, or 4 and above can be calculated from the NMR spectra. The fraction of ethylenes in longer blocks and the sulfur dioxide contents of the polymers can also be determined from the NMR data. The NMR results indicate that the distribution of ethylenes among the different structures is not that expected for a random copolymerization of ethylene and sulfur dioxide but that the arrangement of these structures within the copolymer is random.     

Structural studies on aryl‐substituted enaminoketones and their thio analogues. Part I. Analysis of high‐resolution 1H, 13C NMR and 13C CP MAS spectra combined with GIAO‐DFT calculations

A series of aryl‐substituted enaminoketones and their thio analogues in CDCl₃ solution and in the solid state were studied by the use of high‐resolution ¹H and ¹³C as well as ¹³C cross polarization magic angle spinning (CP MAS) NMR spectra in combination with gauge including atomic orbitals‐density functional theory (GIAO‐DFT) calculations performed at the B3PW91/6–311 + + G(d,p) level of theory using the B3PW91/6‐311 + + G(d,p)‐optimized geometries. The analysis of the ¹³C NMR spectra in solution was done by using the Incredible Natural Abundance DoublE QUAntum Transfer Experiment (INADEQUATE) technique, whereas trends observed in the ¹³C shielding constants, calculated for the compounds studied, were a great help in assigning most of the signals in the ¹³C CP MAS NMR spectra. It was established on the basis of the experimental and theoretical NMR data that both groups of compounds exist in the form of Z‐s‐Z‐s‐E isomers in CDCl₃ solution as well as in the solid state, with the NH hydrogen atom involved in intramolecular hydrogen bonding. This conclusion is in agreement with the fact that some of the compounds studied reveal liquid‐crystalline properties. Three‐bond H, H and C, H coupling constants measured in solution played a crucial role in the structure elucidation. Copyright © 2009 John Wiley & Sons, Ltd.     

An improved 33S nuclear magnetic shielding scale from the gas‐phase study of COS

The ³³S NMR signal of gaseous carbonyl sulfide (COS) was monitored as a function of density for the first time. An extrapolation to the zero‐density limit permitted the measurement of nuclear magnetic shielding of an isolated COS molecule. An improved ³³S shielding scale was established taking the value of 817(12) ppm as the absolute shielding of COS. The new ³³S shielding scale is certainly more accurate than any previous estimation and contains some reference standards, e.g. an isolated SF₆ molecule, a saturated solution of (NH₄)₂SO₄ in D₂O, 2 M aqueous Cs₂SO₄ solution or liquid SF₆, CS₂ and SO₂. The latter results can be applied for the easy estimation of sulfur shielding available from all the measurements of ³³S NMR chemical shifts. Copyright © 2002 John Wiley & Sons, Ltd.     

Influence of the glucosylated β-cyclodextrin inclusion on sulfur trioxide spin-adduct stabilizations and spin-trapping rate processes for DMPO-type spin traps

The effect of CD-inclusion on spin-trapping rates and spin-adduct decay rates for sulfur trioxide radical anion (SO₃ ^??) was investigated. SO₃ ^?? radical was produced with UV photolysis of sodium sulfite in basic aqueous solution, and spin-trapped with various spin traps, i.e., PBN (α-phenyl-N-t-butylnitrone), DMPO (5,5-dimethyl pyrroline-1-oxide), and three other phosphoryl DMPO-type spin traps. A modified β-CD, 6-O-α-d-glucosyl-β-cyclodextrin (G-β-CD) having better inclusion properties than β-CD, was employed. Upon adding excess G-β-CD, decay rates of SO₃ ^?? radical adducts significantly decreased in most spin traps. Half-lives of SO₃ ^?? radical adducts of phosphoryl spin traps were one to two orders of magnitude longer than that of PBN or DMPO, and the G-β-CD addition further extended the half-life time. The spin traps containing phosphoryl-group all showed higher SO₃ ^?? trapping rates than those of PBN and DMPO, but two phosphoryl spin traps achieved slower trapping rates by G-β-CD addition. In addition, the structures of CD-inclusion complexes of spin traps were established by means of 1D and 2D NMR measurements. Based on the results, the influences of inclusion on the spin-trapping rate processes and spin-adduct stabilizations were discussed. We conclude that substituents in DMPO-type spin traps may be modified to provide best spin-trapping capabilities in the presence or absence of CD.     

Gold(I) ‐Nickel(II)‐4,4′‐bpy‐Phosphine Complexes: Synthesis and Multinuclear NMR Study

Silver triflate [AgOTf] assisted de‐bromination gives [Ni(dppm/dppe/(PPh₃)₂) (OTf)₂], which on reaction with 4,4′‐bpy and gold(I) phosphines in dichloromethane medium by the self assemble technique leads to [{(L)Ni}{(4,4‐bpy)Au(PPh₃)}₂](OTf)₄, ( 1,2,3 ) [{(L)Ni(4,4‐bpy)}₄](OTf)₈, ( 4,5,6 ) [L = dppm/dppe/(PPh₃)₂ = diphenyl phosphino‐methane, ‐ethane, bis‐triphenylphosphine, OSO₂CF₃ is the triflate anion]. The maximum molecular peak of the corresponding molecule is observed in the ESI mass spectrum. Ir spectra of the complexes show ‐C=C‐, ‐C=N‐, as well as phosphine stretching. The ¹H NMR spectra as well as ³¹P (¹H)NMR suggest solution stereochemistry, proton movement, and phosphorus proton interaction. Considering all the moieties, there are a lot of carbon atoms in the molecule reflected by the ¹³C NMR spectrum. In the ¹H‐¹H COSY spectrum of the present complexes and contour peaks in the ¹H^?13C HMQC spectrum, we assign the solution structure and stereoretentive transformation in each step.     

NOESY,HOESY, T1 and solid‐state NMR studies on [RuH(η6‐toluene)(Binap)](CF3SO3): a molecule with a strongly distorted piano‐stool structure

Detailed solution‐NMR studies on the distorted ruthenium hydride complex [RuH(η⁶‐toluene)(Binap)](CF₃SO₃) (2) are reported. NOE‐spectroscopy, together with low‐temperature ¹H and ³¹P NMR data, reveals restricted rotation around a P—C bond for a specific axial P—phenyl ring with the activation energy determined via simulation. From ¹⁹F, ¹H HOESY data, the approach of the triflate anion relative to the hydride ligand is established. Comparison of the quadrupole coupling constant C_QF from both solution‐ and solid‐state MAS‐NMR on the deuteride [RuD(η⁶‐benzene)(Binap)](CF₃SO₃) (1‐D) provide information on the nature of the Ru—H bond. Copyright © 2003 John Wiley & Sons, Ltd.     

Formation of the bisulfite anion (HSO3–, m/z 81) upon collision‐induced dissociation of anions derived from organic sulfonic acids

In the negative‐ion collision‐induced dissociation mass spectra of most organic sulfonates, the base peak is observed at m/z 80 for the sulfur trioxide radical anion (SO₃^–·). In contrast, the product‐ion spectra of a few sulfonates, such as cysteic acid, aminomethanesulfonate, and 2‐phenylethanesulfonate, show the base peak at m/z 81 for the bisulfite anion (HSO₃^–). An investigation with an extensive variety of sulfonates revealed that the presence of a hydrogen atom at the β‐position relative to the sulfur atom is a prerequisite for the formation of the bisulfite anion. The formation of HSO₃^– is highly favored when the atom at the β‐position is nitrogen, or the leaving neutral species is a highly conjugated molecule such as styrene or acrylic acid. Deuterium‐exchange experiments with aminomethanesulfonate demonstrated that the hydrogen for HSO₃^– formation is transferred from the β‐position. The presence of a peak at m/z 80 in the spectrum of 2‐sulfoacetic acid, in contrast to a peak at m/z 81 in that of 3‐sulfopropanoic acid, corroborated the proposed hydrogen transfer mechanism. For diacidic compounds, such as 4‐sulfobutanoic acid and cysteic acid, the m/z 81 ion can be formed by an alternative mechanism, in which the negative charge of the carboxylate moiety attacks the α‐carbon relative to the sulfur atom. Experiments conducted with deuterium‐exchanged and deuterium‐labeled analogs of sulfocarboxylic acids demonstrated that the formation of the bisulfite anion resulted either from a hydrogen transfer from the β‐carbon, or from a direct attack by the carboxylate moiety on the α‐carbon. Copyright © 2012 John Wiley & Sons, Ltd.     

An Investigation of Lanthanum Coordination Compounds by Using Solid‐State 139La NMR Spectroscopy and Relativistic Density Functional Theory

Lanthanum‐139 NMR spectra of stationary samples of several solid La^III coordination compounds have been obtained at applied magnetic fields of 11.75 and 17.60 T. The breadth and shape of the ¹³⁹La NMR spectra of the central transition are dominated by the interaction between the ¹³⁹La nuclear quadrupole moment and the electric field gradient (EFG) at that nucleus; however, the influence of chemical‐shift anisotropy on the NMR spectra is non‐negligible for the majority of the compounds investigated. Analysis of the experimental NMR spectra reveals that the ¹³⁹La quadrupolar coupling constants (C_Q) range from 10.0 to 35.6 MHz, the spans of the chemical‐shift tensor (Ω) range from 50 to 260 ppm, and the isotropic chemical shifts (δ_iso) range from ?80 to 178 ppm. In general, there is a correlation between the magnitudes of C_Q and Ω, and δ_iso is shown to depend on the La coordination number. Magnetic‐shielding tensors, calculated by using relativistic zeroth‐order regular approximation density functional theory (ZORA‐DFT) and incorporating scalar only or scalar plus spin–orbit relativistic effects, qualitatively reproduce the experimental chemical‐shift tensors. In general, the inclusion of spin–orbit coupling yields results that are in better agreement with those from the experiment. The magnetic‐shielding calculations and experimentally determined Euler angles can be used to predict the orientation of the chemical‐shift and EFG tensors in the molecular frame. This study demonstrates that solid‐state ¹³⁹La NMR spectroscopy is a useful characterization method and can provide insight into the molecular structure of lanthanum coordination compounds.     

Synthesis and characterization of new polymeric ionic liquid microgels

A new two‐step route toward the synthesis of polymeric ionic liquid microgel particles is presented. In the first step, hydrophilic microparticles were prepared by the concentrated emulsion polymerization of the ionic liquid 1‐vinyl‐3‐ethylimidazolium bromide in the presence of small amounts of N,N‐dimethylenebisacrylamide as a crosslinking agent. In the second step, the bromide anion was exchanged in water with different anions such as BF, CF₃SO, (CF₃SO₂)₂N^?, (CF₃CF₂SO₂)₂N^?, and dodecylbenzenesulfonate, and this resulted in the coagulation of the microparticles, which were easily recovered by filtration. The obtained polymeric ionic liquid microparticles could be swollen in a very broad range of organic solvents, including apolar organic solvents. As an application, glucose oxidase was encapsulated inside polymeric ionic liquid microparticles, which were used in an amperometric biosensor. The response of the biosensor showed excellent values that strongly depended on the nature of the polymeric ionic liquid counteranion in the order of Br^? > BF > (CF₃SO₂)₂N^?. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3958–3965, 2006     

K<Subscript>3</Subscript>VO<Subscript>2</Subscript>(SO<Subscript>4</Subscript>)<Subscript>2</Subscript>: Formation conditions,crystal structure,and physicochemical properties

Potassium oxosulfatovanadate(V) K₃VO₂(SO₄)₂ has been obtained by solid-phase synthesis from K₂SO₄, K₂S₂O₇, and V₂O₅ (2: 1: 1), and its formation conditions, crystal structure, and physiochemical properties have been studied. The conversions of K₃VO₂(SO₄)₂ in contact with potassium vanadates and other potassium oxosulfatovanadates(V) are considered in terms of phase relations in the K₂O-V₂O₅-SO₃ system, which models the active component of vanadium catalysts for sulfur dioxide oxidation into sulfur trioxide. The X-ray diffraction pattern of K₃VO₂(SO₄)₂ is indexed in the monoclinic system (space group P2₁) with unit cell parameters of a = 10.0408(1) Å, b = 7.2312(1) Å, c = 7.3821(1) Å, β = 104.457(1)°, Z = 2, and V = 519.02 ų. The crystal structure of K₃VO₂(SO₄)₂ is built from [VO₂(SO₄)₂]^3? complex anions, in which the vanadium atom is in an octahedral oxygen environment formed by two terminal oxygen atoms (V-O(6) = 1.605(7) Å, V-O(10) = 1.619(7) Å and four oxygen atoms of the two chelating sulfate anions. The vibrational spectra of K₃VO₂(SO₄)₂ are analyzed using these structural data.     

Solid state NMR studies of syndiotactic polystyrene/ethylbenzene and poly(ethylene oxide)/LiCF3SO3 molecular complexes

Solvent dynamics and polymer-solvent interactions in syndiotactic (s) polystyrene (PS)/ethylbenzene (PhEt) clathrates, as well as polymer-salt interactions in the poly(ethylene oxide) (PEO)/LiCF₃SO₃ complex, were characterized by solid state ¹H and ¹³C NMR. ¹H static and ¹H MAS NMR spectra have shown that PhEt molecules in s-PS clathrates retain relatively large, but spatially anisotropic mobility. ¹³C CP/MAS (cross polarization/magic angle spinning) spectra and CP dynamics measured for s-PS-dg/PhEt system indicate that at least a part of PhEt molecules are intercalated between phenyl rings of s-PS. ¹³C CP/MAS NMR spectra show that PEO carbons in complex with LiCF₃SO₃ are more shielded in comparison to neat crystalline PEO. The results (distances) obtained from CP dynamics are in agreement with the published crystal structure of the PEO/LiCF₃SO₃ complex. ¹³C spin-lattice relaxation time measurements have shown that the mobility of PEO in the complex is lower than that in neat crystalline PEO.     

Darstellung und Kristallstruktur von Tetramethylammoniumbromid‐Brom‐SO2‐Addukt, [(CH3)4N]+Br‐�Br2�2SO2

Preparation and Crystal Structure of Tetramethylammoniumbromide‐Bromine‐Sulfur Dioxide Adduct, [(CH₃)₄N]⁺Br^‐�Br₂�2SO₂ Tetramethylammoniumtribromide forms with sulfur dioxide a salt which is characterized by vibrational spectroscopy and crystal structure analysis. [(CH₃)₄N]⁺Br^‐�Br₂�2SO₂ crystallizes monoclinic in the space group P2₁/m with a = 657.4(5) pm, b = 2933.0(5) pm, c = 1462.2(5) pm, β = 91.241(5)° and four formula units in the unit cell. The crystal structure possesses bent infinite chains which consist of alternately arranged bromine and bromide ions. The bromide ions are connected to the molecules of bromine and sulfur dioxide by strong interactions forming a three dimensional network.     

Investigation of the Effect of Metallic Lewis Acid on the Nitrolysis of [3,7-Diacetyl-1,3,5,7-tetraazabicyclo(3.3.1)-nonane] and Hexamine

The effect of metallic ions on the nitrolysis of DAPT [3,7‐diacetyl‐1,3,5,7‐tetraazabicyclo(3.3.1)nonane] and HA (hexamine) was investigated by experimental and theoretical approaches. The combinatorial reagent, M(NO^?₃)_n/Ac₂/NH₄NO₃ (M=Mg²⁺, Cu²⁺, Pb²⁺, Bi³⁺, Fe³⁺ and Zr⁴⁺), was found to be efficient in the experiment of the nitrolysis of DAPT. A key intermediate during the nitrolysis of DAPT was detected by ¹H NMR. The formation mechanism of the intermediate was proposed and analyzed. Some discrepant results for the nitrolysis of DAPT and HA catalyzed by different metallic nitrates were explained based on hard‐soft and acid‐base principle and stabilized energy of ion‐complex. From the latter point of view, some cations with high polarizable ligands, e.g., OSO₂CF₃^?, (CF₃SO₂)₂N^?, and (C₄F₉SO₂)₂N^?, can increase the yields. Two newly designed catalysts, Cu[(CF₃SO₂)₂N]₂ and Cu[(C₄F₉SO₂)₂N]₂, were tested to be highly efficient.     

Synthesis of La(III), Y(III) complexes with polyglycol aldehyde-amino acid Schiff base and their high resolution solid state13C NMR spectra

La (III), Y(III) complexes wit11 diglycol aldehyde his-arginine (H₂DAAR) and tetraglycol aldehyde bislysine (H₂TALY) Schiff bases were synthesized. Thcy were characterized and formulated as La (H₂DAAR) (NO₃)₃. 6H₂0 and Y (H₂TALY) (NO₃)₃. 5H₂0 separately by elemental analyses. The obtained complexes were investigated in detail by high resolution solid state (HRSS)¹³C NMR using cross polarization, magic angle spinning (CPMAS). and total suppression of sidebands (TOSS) techniques. The results are supported by the liquid state 2D-’H-¹³C COSY NMR spectra. Some new information about the splitting peaks of¹³C for -CH = N- group and alkene carbon bands, etc. in HRSS¹³C NMR spectra are given.     

Catalytic Conversion of SO2 Released from the Roasting Process of Copper Sulfides to SO3 by New Nanocatalysts of Vanadium(V) Oxide

Two new silica‐supported vanadium(V) oxide nanocatalysts were synthesized from vanadyl(IV ) sulfate and vanadyl(IV ) oxalate by the sol–gel method. The nanocatalysts were characterized by Fourier transform infrared spectroscopy, thermogravimetry, X‐ray diffraction, X‐ray fluorescence, and field‐emission scanning electron microscopy. The average diameter of the nanocatalysts was ~16 nm. The catalytic activity of both nanocatalysts was investigated in the oxidation of sulfur dioxide (SO₂ ) released from the roasting of copper sulfides to sulfur trioxide (SO₃ ), and the results were compared with those obtained from a commercial BASF (Baden Aniline and Soda Factory) catalyst. It is worth mentioning that our nanocatalysts show higher activity than the commercial catalyst for the oxidation of SO₂ to SO₃ under similar reaction conditions. The suggested electrocatalytic mechanism for the oxidation of SO₂ to SO₃ was confirmed by computational studies. Our calculations indicate that the terminal VO bond of V₂O₅ is likely the most active site for the adsorption and oxidation of SO₂ .