Application of Mössbauer spectroscopy in pyritic and copper calcines studies

In the present study, Mössbauer spectroscopy is applied to the qualitative and quantitative investigation of pyritic and copper calcines prepared by the roasting of untreated concentrates and those which have received a preliminary treatment in a magnetic field. It was established that there are no significant differences in phase content between those calcines which have received a preliminary treatment and those which have not.

New phases were found in copper calcines depending on the intensifying factor applied.     

Complexes of organometallic compounds : XXXIX. synthesis,infrared and mössbauer studies on monoorganotin(IV) complexes with tridentate ligands

Novel complexes RClSntrid, where R is Me, Ph, n-Oct, and trid^2? are dianions of tridentate “planar” ligands with ONO and SNO donor atoms, were synthesized and investigated in the solid state by infrared and Mössbauer spectroscopy. Possible configurations are discussed; polymeric trigonal bipyramidal structures seem to occur, although five-coordinated monomers as well as octahedral dimers (via oxygen or sulfur bridges) are not excluded.     

Multinuclear magnetic resonance and related studies on some organotin(IV) complexes of dithiocarbazates

Synthesis, characterization and geometrical features of pentacoordinated dibutyltin(IV) dithiocarbazate complexes of the type n-Bu₂Sn L (where L = dianion of $\text{S}$-methyl-B-N (2-hydroxy-phenyl) methylene and methyl dithiocarbazate are described. These are obtained as viscous oils from the reactions of n-Bu₂SnO with equimolar proportions of the ligands in benzene. On the basis of UV, IR, NMR (¹H, ¹³C, ¹¹⁹Sn) spectra along with the mass spectral fragmentation pattern a trigonal bipyramidal geometry is proposed. The N atom probably occupies the axial site, while the remaining two donor atoms O and S and the dibutyl groups rest in an equatorial plane. These complexes are active against P.388 Lymphocyte leukaemia system.     

Structural features of some organotin(IV) complexes of semi- and thio-semicarbazones

Some five- and six-coordinated di and tri-n-butyl tin(IV) semi- and thio-semi carbazates have been synthesized. The characterization of these complexes, by IR, NMR (¹H, ¹³C, ¹¹⁹Sn), ¹¹⁹Sn), ¹¹⁹Sn Mössbauer and Mass spectroscopies along with X-ray diffraction, reveals that complexes of biionic ligands of the type Bu₂Sn L″ are five-coordinated having trigonal bipyramidal geometry. However, complexes of monoionic ligands of the type Bu₂SnL′₂ are six-coordinated in a distorted cis-octahedral geometry and Bu₃SnL′ are five-coordinated with a trigonal bipyramidal structure. X-ray structural studies on the compound Bu₂Sn(O.C₆H₄.CH:N.N.CS.NH₂), show that it crystallizes in a monoclinic lattice with a = 16.90 Å, b = 9.71 Å, c = 8.60 Å, and β = 103°45′.     

Mössbauer spectroscopic studies of magnesium nickel ferrites

Mössbauer spectra of magnesium nickel ferrites having spinel structure with varying percentages of nickel were obtained at room temperature. The split extreme high-resonance line could be resolved into two Lorentzians from which the cation distribution was calculated. The calculated cation distributions match very well with those obtained from magnetization measurements as well as from ferromagnetic resonance studies on the same samples. The observed quadrupole split and the hyperfine field values can be rationalized based on the obtained cation distributions.     

Thermal studies on purine complexes. I. Thermal behaviour of some xanthine complexes of cobalt(II), copper(II) and cadmium(II)

Cobalt, copper and cadmium xanthinate tetrahydrates have been prepared in aqueous medium, and characterized on the basis of elemental analysis, IR and ¹HNMR studies. The thermal behaviour of these compounds has been studied using TG, DTG and DSC techniques. Heats of dehydration have been calculated from DSC curves.     

Syntheses of polyfluorophenylcobalt(III) schiff base complexes using organothallium reagents

The complexes RCo(acacen) [R = C₆F₅, p-HC₆F₄, or o-HC₆F₄; H₂acacen = N,N′-ethylenebis(acetylacetonimine)] and RCo(salen) [R = C₆F₅ or p-HC₆F₄; H₂salen = N,N′-ethylenebis(salicylaldimine)] have been prepared by reaction between Co(acacen) or Co(salen) and the appropriate bromobis(polyfluorophenyl)thallium(III) compounds, and have been isolated as pyridinates. Spectroscopic evidence for formation of C₆F₅Co(salophen) [H₂salophen = _N,N′-o-phenylenebis(salicylaldimine)] has also been obtained. The reactivity of the thallium compounds increased in the sequence Ph₂TlBr ? (o-HC₆F₄)2TlBr < (p-HC₆F₄)₂TlBr < (C₆F₅)₂TlBr, and of the cobalt complexes in the sequence Co(salophen) < Co(salen) < Co(acacen). Possible mechanisms are discussed.     

Polarographic studies on the electrode kinetics of the nickel(II) complexes with glycine and some of its derivatives: I. glycine complexes

D.C. polarograms of the Ni(II)-glycine complexes were measured with varying pH values at constant total glycine concentration (0.05 M) and conversely with varying total glycine concentration at constant pH values (3.5, 4.5, 7.5 and 9.5). The current—voltage curves obtained were analysed to determine the limiting currents, the transfer coefficients, and the half-wave potentials, by using the non-linear least squares method. From the dependence of the half-wave potentials on the free glycine concentration, the mechanism of the electrode processes was elucidated. It was shown that the first wave corresponded to the reduction of the Ni²⁺ aquo-complex, the second to the NiG⁺ complex, the third to the NiG₂ complex and the fourth to the NiG^?₃ complex. The kinetic parameters for the four charge transfer processes were determined.The second and third waves were kinetic in character and the rate constants of the dissociation and association reactions between NiG⁺ and NiG₂ and between NiG₂ and NiG^?₃ were determined by analysing the dependence of the kinetic limiting currents on the free glycine concentration.     

Photolysis in aprotic solvents of some alkylcobalt(III) complexes; an ESR and spin-trapping technique study

Photolysis of several alkylcobalt(III) complexes in the visible region λ > 420 nm has been studied by ESR and spin-trapping techniques with nitrosuderene, phenyl-t-butylnitrone (PBN) and 5,5′-dimethylpyrroline-N-oxide (DMPO) and their mixtures. DMPO and PBN give spin adducts of two different radicals; the first is a hydrogen atom coming from the equatorial ligand, and the second is an alkyl-free radical coming from the axial position of the cobalt(III) complexes. This indicates that excitation of the complex is followed by the expulsion of one hydrogen atom and homolytic cleavage of the metalalkyl bond.     

119Sn mössbauer,IR, 1H NMR spectroscopic and thermal decomposition studies on organotin(IV) adducts with glycylglycine

The complexes R₂SnCl₂·(H₂glygly), (H₂glygly = glycylglycine) (R = Me, Buⁿ, Octⁿ, Ph) and RSnCl₃·(H₂glygly)     

IR spectroscopic studies on substituted pyridine N-oxide complexes of tin(IV) chloride in acetonitrile

Complexes of eleven substituted pyridine N-oxide donors with stannic chloride in acetonitrile solution were investigated ultizing IR spectroscopy. Two distinct types of behaviour were noted: (1) Pyridine N-oxide donors containing electron releasing substituents generally form strong complexes with SnCl₄ and exhibit maxima in continuous variation plots at a 2:1 ligand-to-metal ratio. Little or no free ligand is detected in these solutions until this ratio is exceeded. Ligands exhibiting this behaviour include the 2-methyl-, 3-methyl-, 4-methyl-, 4-methoxy- and 4-phenylpyridine N-oxides.(2) Pyridine N-oxide donors containing electron neutral to electron with-drawing substituents generally form weaker complexes with SnCl₄ aM exhibit maxima in continuous variation plots at a 1:1 ligand-to-metal ratio. Free ligand is evident in these solutions even at ligand-to-metal ratios as low as 1:3. Formation plots for these complexes indicate the possibility that 1: 2 and 1:1 ligand to metal complexes exist in the concentration ranges studied. Ligands exhibiting this behaviour include the 4-chloro-, 4-nitro-, 3 and 4-acetyl-pyridine N-oxides and 2-pyridine methanol N-oxide.The complex of 2,6-1utidine N-oxide with SnCl₄ exhibits behaviour characteristic of the 1:1 complexes even though the substituents are electron releasing. This ligand contains the most sterically crowded N-O group in the series, however, and steric factors are invoked to explain this behavior.These results are rationalized in terms of an equilibrium model which includes the postulated existence of oxygen bridged dimers comprising a dominant species in solutions containing the 1:1 complexes. Some supporting ¹H NMR and polarographic data are also presented and discussed.     

Reactions of some electrophilic olefins with (carbonato)bis(triphenylphosphine)- and (carbonato)bis(triphenylarsine)-platinum complexes

Carbonato complexes L₂PtCO₃ (L = PPh₃ or AsPh₃) react with certain electrophilic olegins, such as 1,1-dicyanoolefins, under mild conditions to liberate CO₂. The reaction of L₂PtCO₃ with tetracyanoethylene at room temperature is solvent dependent, and in alcoholic solvents, in contrast to an earlier report, the dicyano complexes, L₂Pt(CN)₂, and tricyanoethenolato complexes, L₂Pt(CN) [OC(CN)C(CN)₂] have been isolated and identified.     

Preparation and electronic spectra of some alkyl- and aryl(2,2′-bipyridine)platinum(II) complexes

A series of alkyl- and aryl-(2,2′-bipyridine)-platinum (II) complexes has been prepared by displacement of the diene ligand in the corresponding cyclooctadiene complexes with 2,2′-bipyridine. Dimethyl(1,10-phenanthroline)platinum(II) was prepared in an analogous way. The electronic spectra of the complexes contain metal to ligand charge transfer bands whose energy is dependent on the nature of the substituents on platinum and on the solvent. It is suggested that π-bonding is important in the phenyl—platinum bond.     

Thermal studies on oxalate complexes. II. Complexes of iron (III) and chromium (III)

The decomposition of solid K₃[Fe(C₂O₄)₃] · 2 H₂O and K₃[Cr(C₂O₄)₃] · 3 H₂O has been studied using TGA and DSC. After dehydration, the chromium compound was found to decompose by the loss of CO in two steps, the loss of CO₂ and additional CO, and finally the loss of CO₂. The final product appears to be either K₃CrO₃ or the mixed oxides of chromium and potassium. Kinetic parameters and enthalpy data are presented for these reactions. In the case of K₃[Fe(C₂O₄)₃] · 2 H₂O, dehydration is followed by the loss of CO₂ and CO, CO₂ alone, and finally CO. The final product appears to be a basic carbonate of the type K₃[FE(O)₂(CO₃)]. Kinetic and thermal data are presented for most of these decomposition reactions.     

Thermal studies on purine complexes. VII. 8-theophylline derivatives and their silver(I) complexes

Four theophylline derivatives: 8-ethyltheophylline (ETH), 8-isopropyltheophylline (IPH), 8-propyltheophylline (PRH), and 8-phenyltheophylline (FTH) have been synthesized and characterized by spectroscopic techniques and thermal analysis. The melting points of these theophylline derivatives increase with the molecular weight, from 263.8°C (ETH) to 384.7°C (FTH). The values of the fusion enthalpy increase in the same order, from 28.4 kJ mol⁻¹ (ETH) to 36.5 kJ mol⁻¹ (FTH).

The interaction of these theophylline derivatives with Ag(I) has been studied by means of spectroscopic techniques, TG, DTG and DSC. In all cases, the pyrolysis of these compounds gave metallic silver.     

Antimony-121 mössbauer spectra of some triphenyl-antimonate(V) schiff base complexes

The 121Sb Mössbauer spectra at 9 and 78 K of R₃Sb-Schiff base complexes which do not have trigonal bipyramidal structures are discussed, and a mer-octahedral structure is proposed.     

A polarographic study of some complexes of Tl(I) with polyoxa macrocyclic ligands

The log β₁ values at 25° for the reaction in aqueous solution of Tl(I) with 15-crown-5, benzo-15-crown-5, 18-crown-6 and dicyclohexyl-18-crown-6 (isomer cis-syn-cis) have been determined by d.c. and a.c. polarographic measurements.     

Thermal studies of Zn(II) hydrazine complexes in the solid state

The synthesis and characterization of ZnL_nX₂ · mH₂O, where L = N₂H₄; n = 3, 2 and 1.5; X = Cl^?, Br^? and $\text{1}\text{2}$SO^2?₄; and m = 0 or 1, have been done and their thermal studies have been carried out using a Shimadzu DT-30 Thermal Analyzer. ZnL₃SO₄, ZnL_2.75SO₄, ZnL₂SO₄, ZnLCl₂ and ZnL_0.5Cl₂ have been synthesized pyrolytically in the solid state from their parent complexes synthesized from solution. Two varieties of ZnL₂Cl₂ synthesized by us are indistinguishable by IR spectroscopy but possess appreciable differences in their thermal profiles. Two forms of ZnL₃SO₄ which are also indistinguishable by IR spectroscopy show noticeable differences in their thermal profiles.     

Structural characterization of a seven-coordinated organotin(IV) complex: Tris(dimethyl sulphoxide)nitratodiphenyltin(IV) nitrate

A seven-coordinated organotin(IV) compound has been obtained and its IR spectroscopic properties and X-ray crystal structure are reported. Crystals are monoclinic (p2₁/c) with unit-cell dimensions: a 16.017(9), b 10.365(5), c 15.994(8) Å, β 96.1(1)°, Z = 4. The structure has been determined from diffractometer data (Cu-K_a radiation) by conventional Patterson and Fourier techniques and refined by block-diagonal least-squares procedure to an R value of 0.093 for 4298 independent reflections. The structure consists of monomeric seven-coordinated cations [Sn(C₆H₅)₂NO₃{(CH₃)₂SO}₃] and NO₃- anions. Coordination around tin is pentagonal bipyramidaI with the bidentate nitrate group and the three dimethyl sulphoxide molecules in the equatorial positions and the two phenyl rings at the apices. Literature on seven-coordinated tin(IV) compounds and nitratotin(IV) complexes is quoted and discussed.     

The reactions of some organotin(IV) chlorides with antimony(V) chloride and boron(III) chloride

The reactions of the organotin chlorides R_nSnCl_4?n(R = Me or Ph; ? n ? 4) with the Lewis acids SbCl₅ and BCl₃ have been investigated by ¹¹⁹Sn and (where appropriate) ¹¹B NMR spectroscopy. The results show that transfer of organo-groups to antimony or boron usually takes place rather than chloride abstraction to give cationic tin(IV) species, and this process is more facile for phenyl than methyl groups. These conclusions have been confirmed in some instances by isolation of the non-volatile reaction products.