Thermoanalytische Untersuchungen zur Bildung kristalliner A12O3-Formen bei der thermischen Zersetzung von Aluminiumchloridhexahydrat

Zusammenfassung Die Zersetzung von AlCl₃ · 6 H₂O wurde im Gebiet 400 bis 1000° mittels Differentialthermoanalyse und Thermogravimetrie in Kombination mit Methoden der Gasanalyse (Massenspektrometrie und Thermogastitrimetrie) untersucht. Während der Zersetzung im nichtisothermen Reaktionsschritt von 200 bis 780° kommt es zu einer relativen Cl^–-Stabilisierung im Cl^–- und OH^–-haltigen amorphen Abbauprodukt. Dieses bildet bei 780° sprunghaft in einem Gitterordnungsprozeß-Al₂O₃. Mit diesem Vorgang ist eine Masseabgabe verbunden, die auf der Abspaltung von HCl und AlCl₃ beruht. H₂O und HC1 aus der Gasphase senken die Aktivierungsenergie des Gitterordnungsprozesses und verschieben diesen nach niedrigeren Temperaturen.

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The decomposition of aluminium chloride hexahydrate was examined in the temperature range 400– 1000° by means of differential thermal analysis and thermogravimetric methods in combination with evolved gas analysis (mass spectra and thermogas-titrimetric methods). In the course of non-isothermal decomposition from 200to 780° it was found that there is a relative Cl^–-stabilization in the Cl^–- and OH^–-containing amorphous product. This amorphous product gives rise abruptly to A1₂O₃ at 780° in a lattice rearrangement process. A decrease of mass is associated with this process, which depends upon the splitting-off of HCl and AlCl₃·H₂O and HCl from the gas phase decrease the activation energy of the lattice rearrangement process, and displace this process toward lower temperatures.

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Résumé On a mis au point, par analyse thermique différentielle et thermogravimétrie en combinaison avec des méthodes de l'analyse des gaz (spectrométrie des masses et titrimétrie thermique des gaz) la décomposition de AlCl₃ · 6 H₂O dans l'intervalle de températures entre 400 et 1000°. Lors de la décomposition dans l'étape de réaction non-isotherme entre 200 et 780° il se produit une stabilisation relative de Cl^– dans le produit de décomposition amorphe à teneurs en Cl^– et OH^–. Celui forme à 780° brusquement, dans un procès d'ordonnement de grille, du-Al₂O₃. Liée à ce procès est une perte de masse basant sur le détachement de HC1 et d'AlCl₃ · H₂O et HCl de la phase gazeuse baissent l'énergie d'activation du procès d'ordonnement de grille et le déplacent vers les températures plus faibles.

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400–1000°, (- ). 200 780° , Cl^– , Cl^– OH^–. 780° -Al₂O₃ . , l AlCl₃. .

     

Thermisches Verhalten und Kristallstruktur von YAl3Cl12

Thermal Behaviour and Crystal Structure of YAl₃Cl₁₂ We determined the thermodynamic data of YAl₃Cl₁₂ ΔH = ?739.9 ± 3 kcal/mol and S = 136.1 ± 4 cal/K · mol by total pressure measurements and ΔH = ?739.1 ± 1.6 kcal/mol by solution calorimetry. Using DTA-investigations we established the phase diagram in the system AlCl₃–YCl₃. The crystal structure was refined on the basis of single crystal data (P3₁ 12; Z = 3; a = 1 046.8(2); c = 1 562.3(3) pm).     

Pt6Cl12·(1,2,4‐C6H3Cl3), a Structurally Characterized Cocrystallization Product of Pt6Cl12

The reaction of platinum(II) chloride with 1,2,4‐trichlorobenzene gives the novel platinum complex Pt₆Cl₁₂·(1,2,4‐C₆H₃Cl₃). It is the first example of an cocrystallization product of platinum(II) chloride and organic molecules whose crystal structure has been established.     

Pressure tuning of electronic states of Cs3Re3Cl12

The pressure shifts of three metal π→π transitions in Cs₃Re₃Cl₁₂ have been measured up to 110 kbar. A comparison of the shifts gives, for the first time, the relative stabilization between a pair of unoccupied antibonding molecular orbitais and between a pair of occupied bonding molecular orbitals as a function of pressure. The results are discussed in terms of the atomic parentage of these molecular orbitals.     

Synthese,Kristallstruktur und magnetische Eigenschaften von TbAl3Cl12

Synthesis, Crystal Structure, and Magnetic Properties of TbAl₃Cl₁₂ TbAl₃Cl₁₂ was synthesized and the crystal structure was determined from single crystal X‐ray diffraction data for the first time. The compound crystallizes trigonally in space group P3₁12 with a = 1049.8(1) and c = 1567.3(2) pm. Terbium cations are located in quadratic antiprisms of chloride anions. Magnetic measurements were performed to study the interactions between Tb³⁺ and Cl^–. Magnetic data were interpreted by ligand field calculations applying the angular overlap model.     

Die Massenspektren von Pd6Cl12, Pt6Cl12 und PdnPt6−nCl12

Mass Spectra of Pd₆Cl₁₂, Pt₆Cl₁₂, and Pd_nPt_6?nCl₁₂ Pd₆Cl₁₂, and Pt₆Cl₁₂ and both together are volatilised in a mass spectrometer. 3 Cl and 1 Pd have approximately the same mass, therefore isotopes of Pd and Pt are used (¹⁰⁸Pd, ₁₉₄Pt). With an ionisation energy of 50 eV part of the vapourised molecules is strongly fragmented. With a lower ionisation energy the molecule ions Pd₆Cl₁₂⁺, Pt₆Cl₁₂⁺ and Pd_nPt_6?nCl₁₂⁺ are only observed.     

Die thermodynamische Stabilität der Molekeln Pd6Cl12, Pd6Br12 und Pt6Cl12

Thermodynamic Stability of Pd₆Cl₁₂, Pd₆Br₁₂, and Pt₆Cl₁₂ Molecules Vapour pressure data of PdCl₂ and PdBr₂ taken from the literature have been used to get new informations regarding the vapourization of Pd₆Cl₁₂ molecules. Using mixtures of PdCl₂ and AgBr as source materials, besides Pd₆Cl₁₂ molecules the vapourization of Pd₆Cl_12-nBr_n with n = 1 – 8 has been observed in a mass spectrometer. Semi quantitative observations concerning the vapourization of Pt₆Cl₁₂ molecules from a PtCl₂ solid are reported. Heats of formation and standard entropy data for the molecules Pd₆Cl₁₂, Pd₆Br₁₂ and Pt₆Cl₁₂ are given.     

Structure and magnetic properties of the ferromagnetic Cu3Cl12(6)- trimer in [(NH3C2H4)3NH]2Cu3Cl14

The crystal structure consists of a strongly hydrogen bonded network of tris(N-ethylammonium)ammonium cations, Cu3Cl12(6)- trimeric species, and Cl- anions. The Cu3Cl12(6)- trimers are formed by two distorted tetrahedral CuCl4(2)- anions linked to a central square planar CuCl4(2)- anion via semicoordinate Cu-Cl...Cu mu1 bridges. The central copper ion shows only small deviations from ideal D4h symmetry, while the terminal copper ions show a mild distortion from D2d symmetry with an average trans Cl-Cu-Cl angle of 136.0 degrees. The semicoordinate linkages provide a ferromagnetic exchange pathway between the copper ions with J/k = 6.91(3) K. Short Cl...Cl contacts (3.67-3.90 angstoms) lead to very weak antiferromagnetic coupling between the ferromagnetically coupled trimers.     

Synthesis and structures of Sc7Cl12 and Zr6Cl15

The indicated nine-electron clusters of scandium and zirconium are formed in transport reactions at 880/900°C and 750/600°C, respectively. Sc₇Cl₁₂ (R¯3, a – 12.959(2), c – 8.825(2), Z – 3) can be described as c.c.p. Sc₆Cl₁₂ clusters with isolated metal atoms in all octahedral interstices or as Sc³⁺(Sc₆Cl₆ⁱCl₆^i?a) ^3? with Sc³⁺ in Clⁱ octahedra between Sc₆Cl sheets. Metal-metal distances within the cluster are 3.201?3.230(2) Å. Zr₆Cl₁₂ⁱCl crystallizes in the Ta₆Cl₁₅ structure (Ia3d, a – 21.141(3) Å, Z – 16) with d(Zr? Zr) = 3,199–3.214(4) Å. Apparent residual electron density is found in the center of both clusters, amounting to Z～7.6 (Sc) and ～6 (Zr) based of refinement of oxygen in these positions. The effect is thought to probably arise from errors in the diffraction data rather than partial incorporation of light nonmetal atoms such as oxygen or fluorine. Observed metal-metal distances are compared with those in other clusters.     

Synthesen,Eigenschaften und Kristallstrukturen der Cluster‐Salze Bi6[PtBi6Cl12] und Bi2/3[PtBi6Cl12]

Syntheses, Properties and Crystal Structures of the Cluster Salts Bi₆[PtBi₆Cl₁₂] and Bi_2/3[PtBi₆Cl₁₂] Melting reactions of Bi with Pt and BiCl₃ yield shiny black, air insensitive crystals of the subchlorides Bi₆[PtBi₆Cl₁₂] and Bi_2/3[PtBi₆Cl₁₂]. Despite the substantial difference in the bismuth content the two compounds have almost the same pseudo‐cubic unit cell and follow the structural principle of a CsCl type cluster salt. Bi₆[PtBi₆Cl₁₂] consists of cuboctahedral [PtBi₆Cl₁₂]^2? clusters and Bi₆²⁺ polycations (a = 9.052(2) Å, α = 89.88(2)°, space group P 1, multiple twins). In the electron precise cluster anion, the Pt atom (18 electron count) centers an octahedron of Bi atoms whose edges are bridged by chlorine atoms. The Bi₆²⁺ cation, a nido cluster with 16 skeletal electrons, has the shape of a distorted octahedron with an opened edge. In Bi_2/3[PtBi₆Cl₁₂] the anion charge is compensated by weakly coordinating Bi³⁺ cations which are distributed statistically over two crystallographic positions (a = 9.048(2) Å, α = 90.44(3)°, space group ). Bi₆[PtBi₆Cl₁₂] is a semiconductor with a band gap of about 0.1 eV. The compound is diamagnetic at room temperature though a small paramagnetic contribution appears towards lower temperature.     

Synthesis of Pure Al35Cl3 and Al37Cl3

Chemically and isotopically pure Al³⁵Cl₃ and Al³⁷Cl₃ are synthesized from Al (s) and HCl (g). The yield is quantitative and no measurable decrease in isotopic content from HCl to AlCl₃ takes place.