Complexes In DMSO Research Articles

Studies on gold(II) complexes with hard and soft donor ligands. Part IV. A reactivity study in solution using EPR spectroscopy

The reactions of Au(II) complexes, cis-[Au(mta)2Cl]Cl (1a), trans-[Au(mta)2Cl]Cl (1b), [Au(mta)2Cl]2Cl2 (1c), Au(pma)Cl (2a), Au(pma)Br (2b) and Au2(pma)Cl4 (2c), where mta and pma are the deprotonated ligands of o-methylthioaniline (Hmta) and N-(2-pyridylmethyl)-2-mercaptoaniline (Hpma), respectively, are reported. When these complexes are reacted with selected ligands containing nitrogen donors, the resulting EPR spectra are indicative of coordination with the nitrogen of the incoming ligand. Both compounds 2a and 2c react with cysteine (cys) in DMF solution to produce the stable reaction product [Au(pma)(cys)]2 (2e), the EPR spectrum of which indicates the presence of two interacting gold(II) ions to form a dimeric system. A radical formed during the course of the reaction of 2c with CN− in DMSO solution which exhibits a multiline EPR spectrum with a g value of 2.003 may be due to the formation of pyridine-N-oxide anion radical subsequently stabilized by either DMSO complex formation and/or σ-bond formation to the central metal atom.

Electrochemical behaviour of zeolite-encapsulated cobalt phthalocyanine complex in DMSO and DMF solutions

Electrochemical behaviour of zeolite-encapsulated cobalt phthalocyanine complex in DMSO and DMF solutions

Electrochemical reduction of Fe(III), Cr(III), and Mn(III) porphyrin complexes in DMSO

The half-wave potentials are given for the electrochemical reduction of Fe(III), Cr(III), and Mn(III) porphyrin complexes. Cyclic voltamperometry was used to study the reversibility of these reactions. An effect was demonstrated for the structure of the porphyrin ligand on the half-wave potentials for the reduction of the Mn(III) complexes.

Radical polymerization of methyl acrylate initiated by styrene‐arsenic sulphide complex

AbstractA styrene‐arsenic sulphide complex in DMSO at 85 ± 0.1°C initiates radical polymerization of methyl acrylate over 90 min under a N2 blanket. Conversion reaches 83% without gelation and results in the formation of polymer having average degree of polymerization 710. Analysis of the kinetic data (up to 29% conversion) indicates that the system follows ideal kinetics. The reaction is retarded by hydroquinone. The overall activation energy and value of k2p/kt are 96 kJ mol−1 and 6.9 × 10−3 litre mol−1 s−1, respectively.

ChemInform Abstract: Effect of Solvent on Sequential Two‐Electron Transfer in Bis(1,3,5‐triketonato)dicopper(II) Complexes.

The cyclic voltammetry of bis(1-phenyl-1,3,5-hexanetrionato) dicopper(II) has been investigated in different solvents over a scan range of 10 3 V/s. Comparisons of the behavior of this complex in DMF, DMSO, and pyridine in the presence and absence of sodium ion show that the electron-transfer properties are strongly solvent dependent

ChemInform Abstract: Synthesis and Structure of Carbonyl‐Containing Sulfonium Silver Complexes (IV) in the System DMSO (I) ‐ HX ‐ Ketone (III), (V).

ChemInform Abstract: Synthesis and Structure of Carbonyl‐Containing Sulfonium Silver Complexes (IV) in the System DMSO (I) ‐ HX ‐ Ketone (III), (V).

Mössbauer studies on cytochrome b models: bis ligated complexes of iron(III) protoporphyrinate IX with imidazole and substituted imidazoles

Iron-57 Mössbauer spectra at 80 K have been recorded for a series of bis ligated complexes of iron(III) protoporphyrinate IX (3,7,12,17-tetramethyl-8,13-divinylporphyrin-2,18-dipropionate)[FeL]+ with imidazole (Him), 1-methylimidazole (1Me-im), and 2-methylimidazole (2Me-im). The spectra were recorded in frozen solutions of dimethyl sulphoxide (dmso), acetone, and 50%(v/v) ethanol–water and also in the presence of hydrogen-bonding agents such as trifluoroethanol or 1,10-phenanthroline in acetone. This is the first report of Mössbauer spectroscopic studies on the solvent dependence of a series of substituted imidazole complexes of [FeLCl]. Significant new results are obtained which are interpreted in the light of reported e.s.r., n.m.r., and electronic absorption data. A value of 2.43 mm s–1 for the quadrupole splitting (ΔEQ) of the imidazolate complex [FeL(Him)(im)] is assigned to a parallel orientation of the planar axial ligands, whereas a value of ΔEQ= 1.87 mm s–1 for the [FeL(2Me-im)2]+ is assigned to a perpendicular orientation of the imidazole planes. Large linewidths of about 0.6–0.98 mm s–1 are attributed to the presence of a statistical distribution of imidazole planes around the thermodynamically stable arrangement. The influences of hydrogen bonding on the Mössbauer parameters are discussed. The 2Me-im complex and the 1Me-im complex in dmso show slow spin–lattice relaxation at 80 K.

First synthesis and characterization of platinum(II) and palladium(II) complexes of some ?-carboline hydrochloride alkaloids and their decomposition products in DMSO

Platinum(II) and palladium(II) complexes of general formulatrans-[MCl2LL] (M=Pt or Pd, L, L′=β-carboline; M=Pt, L=β-carboline, L′=ethene; β-carboline alkaloids are harmaline, harmine, harmalol as hydrochloride derivatives) have been prepared for the first time. The structures were assigned and identified on the basis of their CHN analyses, i.r. and1H n.m.r. spectra. The decomposition products of these complexes in DMSO have been described.

Electrochemistry of the quasi-reversible bis[2-ethyl-2-hydroxybutanoato(2–)]-oxochromate-(V) and -(IV) and bis[2-hydroxy-2-methylbutanoato(2–)]oxochromate-(V) and -(IV) redox couples and the crystal and molecular structure of sodium bis[2-ethyl-2-hydroxybutanoato(2–)]oxochromate(V)sesquihydrate

The CrV–CrIV redox couples of the complexes [Cr(ehba)2O]1–/2–[ehba = 2-ethyl-2- hydroxy-butanoate(2–)] and [Cr(hmba)2O]1–/2;–[hmba = 2-hydroxy-2-methylbutanoate(2–)]— exhibit quasi-reversible redox behaviour in both dimethyl sulphoxide (dmso) and dichloromethane. Solutions of the chromium(v) complex in dmso are stable for a year or more at room temperature, if they are stored in the dark. The chromium(IV) complex is much more reactive, but still has a lifetime on the minutes time-scale in dmso or CH2Cl2 under ambient conditions. The X-ray structure of Na[Cr(ehba)2O]·l.5H2O has been determined. It crystallises in the monoclinic space group C2/c, a= 23.733(6), b= 12.424(3), c= 19.678(6)A, β= 108.30(3)°, and Z= 12. The chromium complex has a distorted trigonal bipyramid of oxygen donor atoms, with the two carboxylate oxygens occupying the axial sites. The crystallographic analysis indicates that the reasons for the unusual stability of this complex and the reversibility of the CrV–CrIV redox couple lie, at least partially, in the steric protection that is caused by the ethyl substituents. Another important factor that leads to the high chemical stability of CrV in aprotic solvents, such as dmso and CH2Cl2, is that it is a weak oxidant in these solvents.

13C nuclear magnetic relaxation study of complexing of alcohols, carbohydrates, and dioxane in dimethyl sulfoxide

1. The values of the auto- and cross-correlation times of the CH vectors of molecules of alcohols, carbohydrates, and 1,4-dioxane in DMSO were obtained with the method of13C nuclear magnetic relaxation. A comparison of the experimental values and the values of the correlation times calculated with the modified Kirkwood-Steele-Huntress theory showed that the cross-correlation times can be used for predicting the most probable conformations of the molecules in solutions. 2. It was found that the probability of formation of an OH ... DMSO complex increases with an increase in the number of OH groups in the molecule.

Silver Iodide Complexes in DMSO and DMF Solutions.

Etude par diffraction RX. Avec un exces d'iodure, on observe la formation de complexes AgI 3 2− , mononucleaire, plan, triangulaire, Pour I/Ag faible, formation de complexes polynucleaires ou les atomes A g sont relies par des ponts d'iodures

ChemInform Abstract: A Simple Preparation of Five‐Carbon Chiral Allylic and Homoallylic Alcohol Synthons.

AbstractReaction of (S)‐O‐benzylglycidol (I) with lithium acetylide ethylenediamine complex (II) in DMSO at temperatures below 5°C yields the terminal acetylenic alcohol (III), whereas at room temperature a mixture of the isomeric acetylenic alcohols (III) and (IV) is formed.

ChemInform Abstract: Synthesis and Crystal Structure of the Homoleptic Thioether Ruthenium Complex (Ru(1,4,7‐trithiacyclononane)2)(BPh4)2·2 Me2SO.

AbstractThe complex cation of (I) could be prepared by reaction of RuCl3·6 H2O with trithianonane (excess) in DMSO at elevated temp. or by reaction of (RuCl2(C6H6))2 with the ligand in MeOH at 20 °C. Recrystallization of the complex in DMSO in the presence of NaBPh4 yields (I) (no yield given) which crystallizes in the space group P21/c with Z=2.

Dissolution mechanism of cellulose in SO2–amine–dimethylsulfoxide

The dissolution mechanism of cellulose in SO2–amine–dimethylsulfoxide systems was studied by using 1H- and 13C-NMR spectroscopy. SO2 and amine (diethylamine or triethylamine) were found to form a complex in DMSO, and the SO2–amine complex, in turn, reacts with an alcoholic hydroxyl group of methanol to produce a new complex. In the case of cellulose, it was proved that all hydroxyl groups in cellulose react with the SO2–amine complexes and form the same complexes in the solution state as those formed in methanol.

Thermodynamics of Tetrahedral-Octahedral Configurational Interconversions in Co(II) Complexes. The Ligand Substitution Reaction between Tetrahedral [Co(hmpa)4]2+ Ion and L (L = FA, NMF, DMF, DEF, or DMSO) in Nitromethane

Abstract Tetrahedral [Co(hmpa)4]2+ ion undergoes a single step reaction with L (L=FA, NMF, DMF, DEF, or DMSO) to form an octahedral [Co(hmpa)2L4]2+ ion in nitromethane. The temperature dependences of the equilibrium constants of tetrahedral-octahedral configurational interconversions exhibit similar values of ΔH=−30–−33 kJ mol−1 and ΔS=−115–−149 J mol−1 K−1 respectively except for larger values for the DMSO complex.

Photolytic Formation of a Uranium(V)–DMSO Complex and the Paramagnetic Shift of DMSO by Uranium(V)

Abstract A U(V)-DMSO complex (DMSO=dimethyl sulfoxide) formed by photoreduction of [UO2(dmso)5]2+ was stable in acid-free DMSO and a small quantum yield of U(V) was attributed to the difficulty in electron transfer from ligands to U(VI). The paramagnetic shift of DMSO by U(V) indicates that only the pseudo-contact shift is induced.

17O NMR investigation of the hydration of L-Alanine and L-Proline in water/Me 2SO mixtures

The hydration state of L-Alanine and L-Proline has been assessed via 17O NMR. At neutral and basic pH, two water molecules are hydrogen bonded at the carboxylate group, one to each oxygen, whereas a third water molecule is hydrogen bonded to the protonated COOH group at acidic pH, via the hydroxyl hydrogen. The possibile formation of dimers and/or higher complexes in DMSO is indicated not only from the chemical shift but also from the linewidth of the amino acids.

Thin-Layer Chromatographic Separation of DMSO Complexes of Metal Ions

Abstract Thin layer chromatography of DMSO complexes of some metal ions in a large number of solvent systems was carried out. The specific separation of DMSO complex of Hg2+ from others have been achieved in ethyl acetate media. Other important separations of metal - DMSO complexes are : Ni2+ - Co2+, Ce3+ - La3+ and Zn2+ - Mn2+. Some other possible separations are also reported.

Bivalent Cobalt Complexes with 1-(2-Pyridylazo)-2-naphthol and Analogous Ligands

Abstract Bivalent cobalt complexes with the title ligands were synthesized, isolated, and characterized by absorption spectra and magnetic moments. It has been suggested that the cobalt(II) complexes have more flexible structures than the corresponding cobalt(III) complexes. The cobalt(II) complexes were found to be oxidized to the cobalt(III) complexes in DMSO in the presence of copper(II) ions. Cyclic voltammetry elucidated the reversible CoII/CoIII couples of the cobalt complexes in acetonitrile. The values of E1⁄2 for the CoII/CoIII couples were found to depend on the coordinating ligands. The relation between E1⁄2 and pKa of the ortho-hydroxyl group in the ligands was discussed.

Stability constants of zinc halide complexes in DMSO—water and DMF—water mixtures

The overall stability constants of zinc bromide and iodide complexes in DMSO—water and those of zinc chloride, bromide and iodide in DMF—water mixtures have been determined potentiometrically at mole ratios about 0.2–1 for the organic solvents at 25°C and in a 0.5 M ammonium perchlorate ionic medium. The complex formation is much stronger in DMF and its mixtures than in DMSO and the log βs are generally higher in solvent mixtures than those expected from the values measured in the pure components.