Complexes In DMF Research Articles

Polymerization of bis(2-bromo-4,6-dichlorophenoxo)bis(pyridine) copper (II) complex in DMF by electroinitiation

Polymerization of bis(2-bromo-4,6-dichlorophenoxo)bis(pyridine) copper (II) complex was achieved in dimethylformamide by electrooxidation. A cyclic voltammogram (CV) of the complex was obtained in dimethylformamide in advance. Constant potential yielded polymers in anode compartment only under nitrogen atmosphere and air. In the final polymer product, incorporation of neither the ligand nor the copper was observed and the post-polymerization proceeded in the absence of current. The structural analyses of the polymers were done by 13C n.m.r., 1H n.m.r., FTi.r. spectroscopy, differential scanning calorimetry (d.s.c.) and dipole moment measurements. The molecular weight of the polymer was determined by cryoscopic method. The poly(dihalophenylene oxides) obtained at different potentials were found to be similar in structure and both 1,2 and 1,4 catenations took place at roughly equal rates.

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

Electro-initiated polymerization of bis-(2,4,6-tribromophenoxo) ethylenediamine copper(II) complex in DMF and its kinetic study by cyclic voltammetry

The decomposition of bis-(2,4,6-tribromophenoxo) ethylenediamine copper(II) complex in dimethylformamide by electro-oxidation yields low molecular weight (4.5 × 10 3) linear poly(dibromophenylene oxide). Electro-initiated polymerization was accomplished upon oxidation by a constant potential electrolysis under air or under N 2 at room temperature. Polymerization conditions were based on the peak potentials measured by cyclic voltammetry. Constant peak potentials carried out at anodic and cathodic peak potentials yielded polymers in the anolyte only. The kinetics of the polymerization were followed by obtaining the unreacted monomer concentration by in situ cyclic voltammetry measurements during electrolysis. The characterization of the polymer was performed by 1H-NMR, 13C-NMR and FTIR spectroscopies. For determination of M n , the isopiestic method was used.

An X-Ray Diffraction Study on the Structure of Solvated Cadmium(II) Ion and Tetrathiocyanatocadmate(II) Complex in N,N-Dimethylformamide

Abstract The structure of solvated cadmium(II) ion and the tetrathiocyanatocadmate(II) complex in N,N-dimethylformamide (DMF) has been determined by means of X-ray diffraction at 25 °C. The radial distribution curve for a cadmium(II) perchlorate DMF solution is well explained in terms of the presence of the octahedral [Cd(dmf)6]2+ complex with the Cd–O bond length of 229.6(4) pm, which is practically the same as that within [Cd(dmso)6]2+ in DMSO and [Cd(H2O)6]2+ in H2O. It is also found that the tetrathiocyanatocadmate(II) complex has a tetrahedral structure, [Cd(NCS)3(SCN)]2−, with three Cd–N and one Cd–S bonds, the distances being 223(2) and 257(2) pm, respectively. The coordination structure of the complex in DMF is different from that found in aqueous solution, [Cd(NCS)2(SCN)2]2−.

New approach to the synthesis of alkylthioamides using catalysts containing cobalt complexes

1. It is shown that alkylthioamides can be synthesized in high yields by the reaction of elemental sulfur with alkylacetylenes in DMF solution, catalyzed by cobalt complexes. 2. In the presence of phosphine, cyclooctasulfane and DMF complexes of cobalt are able to isomerize the inner triple bond in alkynes into the terminal position.

Calorimetric and Raman Spectroscopic Studies of Cadmium(II) Thiocyanato Complexes in N,N-Dimethylformamide

Abstract Formation of thiocyanato complexes of cadmium(II) ion has been calorimetrically studied in N,N-dimethylformamide (DMF) at 25 °C. Calorimetric data obtained were well explained in terms of the formation of a series of four mononuclear [CdXn](2−n)+ (n=1–4, X=SCN) complexes, and their formation constants, enthalpies, and entropies were determined. Raman band shifts for the C–S stretching vibration of SCN− ion indicated that SCN− ion binds to cadmium(II) ion only with the N end within the mono- or dithiocyanato complex, [Cd(NCS)]+ or [Cd(NCS)2]. Within the tri- and tetrathiocyanato complexes, thiocyanate ions binds with both the N and S ends, and the coordination modes, [Cd(NCS)2(SCN)]− and [Cd(NCS)3(SCN)]2−, were suggested. The coordination modes for the di- and tetrathiocyanato complexes in DMF, [Cd(NCS)2] and [Cd(NCS)3(SCN)]2−, are different from those in water, [Cd(NCS)(SCN)] and [Cd(NCS)2(SCN)2]2−. It is thus shown that the N-bonding becomes more favorable in DMF than in water. Such a result may mainly be ascribed to relatively weakened solvation of the SCN− ion in DMF, especially at the N atom site which is hydrogen-bonded with water molecules but not with DMF.

Dilatometric studies of reaction volumes for the formation of metal complexes in several solvents

A convenient technique is described to determine reaction volumes by means of direct dilatometry. Reaction volumes were determined for the following complexation reactions: formation of monoamminenickel(II) in water (−0.1±0.5 cm3-mol−1); formation of the 1:1 nickel(II) complex with isoquinoline in methanol and ethanol (3.2±0.1 and 1.1±0.1 cm3-mol−1, respectively); formation of the 1:1 isothiocyanatoiron(III) complex in water, Me2SO, and DMF (8.9±0.2, 12.4±0.7, and 25.1±0.3 cm3-mol−1, respectively); formation of the 18-crown-6 potassium complex in water (10.9±0.2 cm3-mol−1). We discussed these values in terms of electrostriction and molecular size.

Fluorine-containing organozinc reagents: II. The crystal structure of (1, 1-dichloro-2, 2, 2-trifluoroethylzinc chloride) · 2(dimethylformamide)

The DMF complex of 1, 1-dichloro-2, 2, 2-trifluoroethylzinc chloride, a key intermediate in the one pot synthesis of CF 3CCl 2-substituted alcohols, has been isolated and its structure determined by 13C NMR spectroscopy and by X-ray diffraction. This is the first X-ray structural study of a perhalogenated alkylzinc halide and the results show the DMF complex to be monomeric.

ChemInform Abstract: Conductomeric Investigations on Solvatochromic Nickel(II) Complexes in Dichloroethane and N,N‐Dimethylformamide.

AbstractConductivity measurements are performed on solutions of the mixed ligand complexes (I) in dichloroethane and DMF.

Calorimetric and Spectrophotometric Studies of Ternary Copper(II) Complexes with Bromide Ions and 2,2′-Bipyridyl in N,N-Dimethylformamide

Abstract Mixed ligand complexation of copper(II) with bromide ions and 2,2′-bipyridyl (bpy) has been calorimetrically studied in N,N-dimethylformamide (DMF) containing 0.16 mol dm−3 (C2H5)4NClO4 at 25°C. Complexation of the metal ion with 2,2′-bipyridyl has been also studied in the same solution. The calorimetric titration curves obtained were satisfactorily explained in terms of formation of the mononuclear [CuBrp(bpy)q](2−p)+ (denoted as (1pq)) complexes such as (101), (102), (103), (111), (121), and (112), and their formation constants and enthalpies were determined. The mixed ligand (111), (112), and (121) complexes are quite stable and yielded to a large extent in the DMF solution. Electronic spectra of these complexes have been measured in DMF over the range 400–1500 nm. The thermodynamic quantities of formation and electronic spectra of the complexes thus obtained are discussed in connection with the coordination structure of the complexes in DMF. The formation of the five-coordinate [Cu(bpy)2(dmf)]2+ and [CuBr(bpy)2]+ complexes is suggested in the DMF solution as well as in crystal.

Acetone Salicylhydrazone Complexes of Dioxouranium(VI) Nitrate, Acetate and Sulphate

Abstract Acetone salicylhydrazone (ASH) complexes of the type UO2 (ASH)X2 (X=No3, CH3 COO, ½ SO4) have been synthesized and their structure studied by molecular weight, molar conductance, i.r. and Raman spectra in the solid state. The molar conductance of the uranyl nitrate and acetate complexes in a 0.001 M solution of DMF corresponds to 1:2 electrolytes suggesting the dissociation of the complexes in solution presumably due to their solvolysis. The molar conductance of the uranyl nitrate and the uranyl sulphate complexes in ethanol and the uranyl sulphate complex in DMF suggests their non-electrolytic nature in the respective solvents. I.r. spectra indicate that ASH acts as a neutral bidentate ligand via >C˭O and >C˭N groups. Raman spectra indicate that the linearity of the UO++ 2 group is maintained in the complexes. The uranium atom is eight-coordinate in the nitrate and the acetate complexes and six-coordinate in the sulphate complex in the solid state.

Calorimetric and Spectrophotometric Studies of Chloro Complexes of Nickel(II) and Zinc(II) Ions in N,N-Dimethylformamide

Abstract Complexation of Ni(II) and Zn(II) with Cl− ions has been studied by calorimetry and spectrophotometry in N,N-dimethylformamide (DMF) containing 0.4 mol dm−3 (C2H5)4NClO4 as a constant ionic medium at 25 °C. Calorimetric titration curves obtained in each system were well-explained in terms of formation of [MCln](2−n)+ (n=1–4 and M2+=Ni2+ or Zn2+), and their formation constants, enthalpies and entropies were determined. Formation of the nickel(II) chloro complexes in DMF was also supported by spectrophotometry. In the nickel(II) chloride system, the stepwise enthalpy ΔH3° and entropy ΔS3° values are remarkably large and positive as compared with the ΔHn° and ΔSn° (n=1, 2, and 4) values. Individual electronic spectra of nickel(II) ion, [NiCl]+ and [NiCl2] are significantly different in both intensities and peak positions from those of [NiCl3]− and [NiCl4]2− over the range 300–850 nm. These thermodynamic and spectrophotometric results were explained in terms of formation of the octahedral [NiCl]+ complex as well as [Ni(dmf)6]2+ and of formation of the tetrahedral [NiCl3]− and [NiCl4]2− complexes in DMF. On the other hand, in the zinc(II) chloride system, the ΔSn° (n=1 and 2) values are large and positive, but the ΔSn° (n=3 and 4) values are significantly small. The corresponding ΔHn° (n=1 and 2) values are positive but the ΔHn° (n=3 and 4) values are significantly negative. It is thus postulated that the [ZnCln](2−n)+ (n=2 and 3) complexes have the tetrahedral coordination structure as well as the [ZnCl4]2− complex in DMF.

ChemInform Abstract: Monobactams: Expeditious Synthesis of Azetidinone‐1‐sulphonates and Selected Alternatively‐Activated Analogues.

AbstractTwo different strategies are applied to prepare monobactams such as SQ 26,180 (II) or the aztreonam precursor (V): sulphonation of an N‐unsubstituted β‐lactam like (I) (e.g with the DMF complex of SO3) or cyclization (e.g using K2CO3) of an acyl sulphamate of type (IV), obtained from threonine (III).

Synthesis and characterization of five-coordinate macrocyclic complexes of nickel(II) and copper(II)

The template condensation of the ligand 1,29,10-tetraphenyl-3,4,7,8-tetraazonona-2,4,6,8-tetraen-1,10-dione and aliphatic diamines like ethanediamine and 1,2-propanediamine in the presence of metal ions, viz. Ni 2+ and Cu 2+, resulted in the formation of pentacoordinate square pyramidal complexes with the hydroxyl ion occupying the axial position. The macrocyclic ligand is coordinated to the central metal ion through four imine nitrogen atoms in a planar fashion. Electronic, IR and ESR spectra as well as magnetic and conductance data corrobarate the above proposition. The electrochemistry of these complexes in DMF has also been discussed.

Characterization studies of some bi- and tetradentate bifunctionalSchiff base complexes with Co(II), Ni(II), and Cu(II)

Co(II), Ni(II) and Cu(II) complexes of some bifunctional arylidene-o-phenylenediamineSchiff bases have been prepared. Formation, stoichiometry and stability of the complexes have been tested in solution using electronic spectral measurements. Characterization of the complexes has been accomplished primarily by elemental analysis, molar conductance as well as electronic and IR spectral measurements. It is concluded that theo,o-hydroxy derivative (L1) acts as a bivalent ONNO tetradentate ligand while the molecules of the other derivatives (L2-L5) are coordinated to the metal ions as bidentate NN ligands. The Cu(II)-L1 complex is suggested to possess a tetrahedral geometry whereas the other complexes are suggested to exhibit a distarted octahedral geometry. The different bands observed in the electronic spectra of the complexes inDMF solutions have been assigned to the π-π*,L →M CT and d-d electronic transitions.

Concerning a second polymorph of the HMX–DMF complex

Concerning a second polymorph of the HMX–DMF complex

Synthesis and Studies of Some Bivalent Metal Complexes of 1-p-Chlorobenzoyl-4-phenyl-3-thiosemicarbazide

Abstract The synthesis, spectra (IR, Visible), magnetic susceptibilites and conductance measurements of a series of bivalent metal complexes of the general formula [M(L-H)2]. nH2O(M = Mn(II), Ni(II), Cu(II) and Cd(II); L=p-CPTS = 1-p-chlorobenzoyl-4-plenyl-3-thiosemicarbazide and n = 1 or 2), [M(L-H)X- nH2O] (M = Co(II), Cu(II); X=Cl, Ac and n = O-3), [Co(L-H)Cl-DMF] (DMF=dimethylformamide) and [HgLCl2] are described. 1H NMR spectra of the ligand and the diamagnetic complexes are discussed. The infrared spectra show that the ligand behaves in a bidentate manner coordinating via the (1NH) and the thiocarbonyl sulphur atoms either in the keto or in the enol form to give five membered ring around the metal ion. Both magnetic and the spectral studies are in favour of an octahedral structure for the brown Co(II) complex, [Co(L-H)Cl (H2O)3], which changes to a green tetrahedral Co(II) complex, [Co(L-H)Cl-DMF], on dissolution of the brown complex in DMF. Also, the stereochemistry of Ni(II)and Cu(II) complexes ha...

PARAMAGNETIC SHIFT AND LIGAND EXCHANGE IN URANIUM(V)-DMF COMPLEX

Abstract The rate of ligand exchange in a U(V)-DMF complex was determined for the first time in N,N-dimethylformamide(DMF) at temperatures below −40°C by using the 1H NMR method. The paramagnetic shift by U(V) was also observed in the 1H and 13C NMR signals of bulk DMF owing to the fast exchange between the first coordination sphere of U(V) and the bulk solvent at 25°C.

Preparation and thermal stability of the U(IV)(SO 4) 2-DMF complex

A new DMF complex of U(SO 4) 2, i.e., U(SO 4) 2·2.2 DMF, was prepared and characterized using chemical analysis, X-ray powder diffraction studies, IR and measurement of magnetic susceptibility variation with temperature in the temperature range 77–300 K. Pyrolysis of the solvate was studied by means of TG under two different experimental conditions, and the actual thermal degradation path was deduced using a microthermobalance.

ChemInform Abstract: MICHAEL ADDITIONS CATALYZED BY METAL(II) COMPLEXES

AbstractUntersuchungen zeigen, daß die aus Co(II)‐ oder Ni(II)‐acetat und 2,2′‐Bipyridyl in DMF gebildeten 1:1‐Komplexe die Michael‐Additionsreaktionen von Chalkon und seinen Derivaten (Ia,b) sowie Methylacrylat (Ic) mit Nitromethan (II) unter neutralen Bedingungen bei Raumtemp. am wirkungsvollsten von allen untersuchten Komplexen aus Co(II)‐, Cu(II)‐ und Ni(II)‐ Salzen und NN‐Liganden katalysieren.