Sur les carbonates basiques de fer (III): II. Préparation,radiocristallographie et spectres IR. du (NH4)2Fe2(OH)4(CO3)2 · H2O

The obtention of the crystalline basic carbonate of iron (III) and ammonium, (NH₄)₂Fe₂(OH)₄(CO₃)₂ · H₂O, is described and its formula is established by chemical analysis and infrared spectroscopy. The powder X-ray diagram could be indexed tetragonally leading to a body centred elementary cell with a = 12,04 ± 0,02 Å and c = 6,62 ± 0,01 Å. The infrared spectra show that in the CO groups either one oxygen atom is linked to one iron atom or, rather, two oxygen atoms are linked to two iron atoms. The symmetry of the NH groups is lower than C_3v. The OH-groups are linked by hydrogen bonds of 2,75 Å. Two sorts of OH-groups can be distinguished, with a radius of approximately 1,34 Å and 1, 48 Å, respectively. The iron atoms are octahedrally coordinated by oxygen atoms, but either the octahedra are deformed or the iron atoms are in part coordinated tetrahedrally.     

Sur les carbonates basiques de fer (III): I. Carbonate basique de fer (III) amorphe

The preparation of a non-stoichiometric basic carbonate of iron (III) is described. The amounts of carbon dioxide and water can vary in large limits, depending on the way the samples are dried. The ratio of Fe₂O₃:CO₂ in a fresh product is nearly one, but decomposition takes place already at room temperature and ambient humidity. When heated slowly, the carbon dioxide is given of in two clear steps, an intermediate product being formed at about 200°C. The basic iron (III) carbonate decomposes between 400° and 500°C to an α-Fe₂O₃ with still a small amount of carbon dioxide. The infrared spectra show that in the freshly prepared products the greater part of the CO ions are linked by two oxygen atoms to two iron atoms, and a smaller part probably only by one oxygen to one iron atom. In the intermediate product, part of the CO^2_₃ ions are linked by two oxygen atoms to one iron atom, or a hydrogenocarbonate group may be formed. The X-ray diagrams taken with Mo K_α rays show only two broad lines.     

Sur un nouveau Complexe entre l'oxyfluorure d'antimoine et l'oxalate. Structure cristalline de (NH4)4H2(C2O4)3(SbOF) 2 · H2O

On a New Complex of Antimony Oxide Fluoride and Oxalate. Crystal Structure of (NH₄)₄H₂(C₂O₄)₃(SbOF) ₂ · H₂O The crystal structure of (NH₄)₄H₂(C₂O₄)₃(SbOF) ₂ · H₂O has been fixed by X-ray diffraction on single crystal (R = 0.025 for 2124 planes). The antimony atom is complexed by the oxalate anions which are bidendate chelates. Antimony coordination is seven (five oxygen atoms, one fluorine atom, and the lone pair E). Antimony environment is a pentagonal bipyramid, one of the axial positions is occupied by the lone pair, the other one by the fluorine atom.     

Etude structurale de derives du fer carbonyle: II. Structure cristalline et moleculaire d'un complexe du fer carbonyle avec la 2-mercapto-pyridine,C5H4N(CO)6Fe2-μ4-S-Fe2(CO)6SC5H4N

The crystal and molecular structure of a complex prepared by reaction between Fe₃(CO)₁₂ and 2-mercaptopyridine and of formula C₅H₄N(CO)₆Fe₂-μ₄-S-Fe₂(CO)₆SC₅H₄N has been determined by a single-crystal X-ray study. The compound crystallises in the monoclinic space group $\text{P}\text{2}{}_1\text{n}$, with Z = 4. Data were collected on a NONIUS CAD-4 automatic diffractometer. The structure was solved both by the heavy-atom method and direct methods and refined to R and R″ values of 0.041 and 0.038 for 2089 independent reflections. The molecule contains four Fe(CO)₃ groups with two ironiron bonds bridged in a different way, and a sulphur atom tetrahedrally coordinated to the four iron atoms.     

Mecanisme de la fixation du fer ferrique sur un copolymere d'ester carboxylique—II. Etude des coefficients de distribution et de la permeation du fer(III)

Experimental determination of distribution coefficients and diffusivity through the Hycar 4021 copolymer of macro-amounts of iron(III) in ethanolic hydrochloric acid lead to the knowledge of the processes involving ethanol. Micro-amounts of iron(III) are fixed on the copolymer by a different process.     

Mecanisme de la fixation du fer ferrique sur un copolymere d'ester carboxylique—I. Etude cinetique et analyse de la composition du copolymere charge de fer(III)

Iron(III) increases markedly the swelling kinetics of Hycar 4021 copolymer in aqueous or ethanolic hydrochloric acid. The distribution of the metallic element in the copolymer corresponds to a partition mechanism. Chemical species not necessary for the electroneutrality balance of the copolymer are also distributed in these media. They form quasi-stoichiometric compounds with internal ferric iron.     

Metall-Schwefelstickstoff-Verbindungen. 17. Die Verbindungen HgN2S · NH3 und 2Hg(NH3)2I2 · S4N4

Metal Sulphur Nitrogen Compounds. 17. Compounds HgN₂S · NH₃ and Hg(NH₃)₂I₂ · S₄N₄ The crystal and molecular structures of the known compounds HgN₂S · NH₃ and of the new inclusion compound 2Hg(NH₃)₂I₂ · S₄N₄ are reported. HgN₂S · NH₃ is orthorhombic, space group Pbca with a = 5.548, b = 10.158, c = 14.919 Å, Z = 8. In the dimeric molecules two Hg atoms are bridged to form eight-membered rings . In addition, each Hg is coordinated by an NH₃ molecule and by an N atom of an adjacent ring. This results in a two-dimensional network. 2Hg(NH₃)₂I₂ · S₄N₄ is tetragonal, space group P4₂/nmc, a = 8.948, c = 13.188 Å, Z = 2. It is an inclusion compound with S₄N₄ molecules in the holes of the lattice of the large Hg(NH₃)₂I₂ tetrahedra.     

Die Komplexe Pyren · 2 SbCl3 und Phenanthren - 2 SbBr3 Phasenverhalten,Präparation und Kristallstrukturen

Complexes Pyrene · 2 SbCl₃ and Phenanthrene · 2 SbBr₃: Phase Behaviour, Preparation, and Crystal Structures The melting diagrams of the systems pyrene-SbCl₃ and phenanthrene-SbBr₃ were studied by DTA. They are quasibinary and display one intermediate phase each of molar ratio 1:2 and melting congruently at 143 and 114°C, respectively. Their structures were determined by X-ray diffraction using single crystals obtained by sublimation. In pyrene. 2 SbCl₃ the two halogenide molecules are arranged on different sides, in phenanthrene - 2 SbBr₃ on the same side of the plane of the aromatic molecule. Sb ?π interactions lead to distances of the Sb atoms from this plane of 315 to 323 pm.     

Thermal decomposition of ammonium jarosite (NH4)Fe3(SO4)2(OH)6

Thermogravimetry combined with mass spectrometry has been used to study the thermal decomposition of a synthetic ammonium jarosite. Five mass loss steps are observed at 120, 260, 389, 510 and 541°C. Mass spectrometry through evolved gases confirms these steps as loss of water, dehydroxylation, loss of ammonia and loss of sulphate in two steps. Changes in the molecular structure of the ammonium jarosite were followed by infrared emission spectroscopy (IES). This technique allows the infrared spectrum at the elevated temperatures to be obtained. IES confirms the dehydroxylation to have taken place by 300°C and the ammonia loss by 450°C. Loss of the sulphate is observed by changes in band position and intensity after 500°C.     

Étude cristallographique du complexe 1-1 du fer(II) et de l'acide thioglycolique

The crystals of the iron(II)-thioglycolic acid complex 1-1, Fe(CH₂SCOO)·H₂O, are monoclinic, with lattice constants a = 7.54±0.02 Å, b = 8.57±0.01 Å, c = 6.95±0.01 Å and β = 90° 57′±9′. The space group is P2₁/c, each unit cell containing four entities Fe(CH₂SCOO)·H₂O. The structure consists of sheets of iron-sulfur chain assemblies. The iron atoms of two chains are connected by double oxygen bridges and thioglycolic anions; each iron is at the center of a highly distorted octahedron.     

Sur la réaction de reformatsky : I. Préparation et réactivité des organozinciques issus de divers crotonates d''alcoyles

Lithiation of (Me₃Si)₃CH by methyllithium (ether-THF) yields (Me₃Si)₃CLi and by t-butyllithium (C₅H₁₂-TMEDA) yields (Me₃Si)₂CHSiMe₂CH₂Li. Only starting material is recovered when (Me₃Si)₃CH is allowed to react with n-butyl- lithium (ether-THF and C₅H₁₂-TMEDA) and t-butyllithium (C₅H₁₂ and C₅H₁₂- THF). (Me₃Si)₄C is lithiated by t-butyllithium (C₅H₁₂-TMEDA) to give (Me₃Si)₃- CSiMe₂CH₂Li, but not by methyllithium (ether-THF and ether-THF-TMEDA). The structures of the lithiated compounds are based on the carbonation products. The above results are explained in terms of carbanion stability and steric effects. Spectral data are reported on the α-silylacetic acids.     

Ein neues Doppelsalz, (NH4)2SiF6 · NH4NO3

A New Double Salt, (NH₄)₂SiF₆ · NH₄NO₃. From a aqueous solutions of (NH₄)₂SiF₆ and NH₄NO₃ crystallizes by cooling to room-temperature a new double-salt of the composition (NH₄)₂SiF₆ · NH₄NO₃. Its hexagonal unit containing two molecules has the dimensions: a₀ = 5.868, c₀ = 14.799 Å.     

Fe2PO5, un phosphate de fer de valence mixte. Préparation et études structurale, mössbauer et magnétique

Fe₂PO₅ is prepared from diverse components of the Fe---P---O system at 900°C in sealed silica tubes in vacuum. The study of a single crystal shows an orthorhombic cell, space group Pnma, with a = 7.378, B = 6.445, C = 7.471 Å and Z = 4. The structure is determined through direct methods and Fourier syntheses and refined to R = 0.027. The phosphorus fills isolated tetrahedra. The Fe^II and Fe^III ions are ordered in distorted octahedra: the octahedra surrounding Fe^II build strings parallel to the b axis and share edges; the octahedra containing Fe^III are connected on both sides of these strings alternatively with the PO₄ tetrahedra. The two types of octahedra share one face. Such an arrangement strongly recalls two out of the three Al₂SiO₅ polymorphs, namely, the kyanite and sillimanite. The Mössbauer spectroscopy exhibits a magnetic transition at 220 K. Below, the spectrum shows a six-line hyperfine pattern for Fe^III and an eight-lines one for Fe^II with a rather weak hyperfine field; above, there are two well differentiated doublets, confirming the absence of electronic charge transfer at room temperature. The magnetic susceptibility, recorded from 90 to 300 K, is typically that of an antiferromagnetic compound with C_M = 7.12, θ_p = −350 K and T_N 250 K. The magnetic interactions are discussed. The electronic localization is explained through structural and crystal field considerations; the electrostatic potential difference between the Fe^II and Fe^III sites is calculated.