- Vibrational spectroscopy and normal coordinate analysis of μ halo hexahalodialuminates ions Al2X7- (X = Cl, Br, I) in some salts and in Friedel-Crafts solutions
-
Infrared and Raman spectra are reported for (Me4N)Al2Cl7, (Et4N)Al2Cl7, KAl2Br7 and CsAl2I7 in the solid state at ordinary temperature.An assignment for practically all the vibrational modes is proposed for the three ions Al2Cl7-, Al2Br7- and Al2I7-.To elucidate the species occurring in the Friedel-Crafts liquids , the spectra of these solutions were also recorded.The quasi identity of the halogenide part of the spectra with the previous one leads to the unique formulation ArH2+Al2X7- for these solutions, in these cases the Al2X7- ion appears at a higher local symmetry of the AlX3 groups than in the solid state.An approximate valence force field calculation confirms the assignments.It also shows the transferability of force constants for a X-AlX3 model.Spectroscopic particularities are explained in terms of different coupling between bridged and terminal stretching modes.
- Manteghetti, Alain,Potier, Antoine
-
-
Read Online
- Complex equilibria in unsaturated vapor over AlBr3
-
Unsaturated AlBr 3 vapor pressure was measured over the temperature and pressure ranges 560-845 K and 54-145 torr by the static method using a quartz diaphragm pressure gauge with increased sensitivity (the confidence interval of pressure, including thermal drift of zero pressure gauge point, was 0.3 torr, and that of temperature, 0.3 K). Two equilibrium models were considered, one including AlBr3 and Al2Br6 and the other, AlBr3, Al2Br6, and Al3Br 9. The molecular constants of all vapor constituents were determined using density functional theory at the B3LYP/6-31G(d,p) level. The thermodynamic functions of all bromides were calculated in the rigid rotator-harmonic oscillator approximation. The enthalpies of independent equilibria for each model were determined by minimizing the residual sum of the squares of pressure discrepancies. According to the first model, 0.5Al2Br6 = AlBr3, ΔHo(298.15) = 13629.1 ± 9 cal/mol. According to the second model, 0.5Al2Br6 = AlBr 3, ΔHo(298.15) = 13638.8 ± 8 cal/mol, and 1.5Al2Br6 = Al3Br9, ΔH o(298.15) = -8528 ± 800 cal/mol. The second model, for which the variance of pressure differs insignificantly from the experimental variance of pressure, should be given preference.
- Rusin,Nisel'Son
-
-
Read Online
- Dimeric Di(tert-butyl)haloalanes and a Monomeric Di(tert-butyl)phosphino- di(tert-butyl)alane
-
The di(tert-butyl)aluminum halides, tBu2AlX (X = Br, I) have been prepared in yields ranging from 55 to 64 % from AlX3 and Lit Bu in a 1: 2 molar ratio in pentane. In the crystal these pyrophoric compounds are dimeric featuring Al-X-Al bridges. The reaction of AlCI3 with LitBu in diethyl ether produced a volatile solvate of composition tBu3Al-Cl- AltBu2(OEt2). Reaction of this species with AlCl 3 at 120 °C yielded a separable mixture of tBu2AlCl and tBu2AlCl(OEt2). tBu2AlCl and tBu 2GaCl react with tBu2PLi to produce the monomeric compounds tBu2E-PtBu2 (E = Al, Ga). The aluminum compound decomposes at 111 °C to give a mixture of the cis/trans-isomers of [tBu(H) Al-PtBu2]2 while at 200 °C only the trans-isomer is formed.
- Krossing, Ingo,N?th, Heinrich,Staude, Siegfried
-
-
Read Online
- Reversible bromide-chloride exchange in zirconium cluster compounds: Synthesis by means of ionic liquids, structures, and some spectral data of (EMIm)4[(Zr6Z)Br18] cluster phases (Z = Be, Fe)
-
The solid-state precursor cluster chlorides Na4[(Zr 6Be)Cl16] and K[(Zr6Fe)Cl15] readily dissolve in Lewis-basic ionic liquids consisting of mixtures of EMIm-Br and AlBr3 (EMIm: 1-ethyl-3-methyl-imidazolium) to give dark colored solutions. From these solutions, the cluster phases (EMIm)4[(Zr 6Fe)Br18] (1) and (EMIm)4[(Zr 6Be)Br18] (2) were obtained in acceptable yields. Crystallographic data of the isostructural phases are the following: monoclinic, P21/c, Z = 2. The data for 1 follow: a = 10.5746(4) A, b = 22.6567(9) A, and c = 13.0260(5) A, β = 111.279(2)°. The data for 2 follow: a = 10.574(2) A, b = 22.681(4) A, and c = 13.041(2) A, β = 111.31(2)°. Compound 1 is the first detailed structurally characterized molecular Fe-centered zirconium bromide cluster phase. In the bromide based ionic liquid, a complete exchange of all the outer and inner chlorides by bromide takes place. Since the inverse reaction, the exchange of all bromides by chlorides, was reported before, this complete ligand exchange can be considered as reversible, with the equilibrium being largely determined by the free ligand concentration. The electronic spectra of a chloride supported cluster precursor in different ionic liquids were measured and analyzed.
- Willems, Johannes B.,Rohm, Henning W.,Geers, Christine,Koeckerling, Martin
-
-
Read Online
- Amorphous aluminum bromide fluoride (ABF)
-
Different octahedral units form the basis of the structures of the very strong Lewis acids aluminum bromide fluoride (ABF) and aluminum chloride fluoride (ACF) (see picture). A structure model for these phases is established in which the octahedra are linked through μ-bridging fluorine atoms and μ3-bridging X atoms (X = Cl, Br). The bridging of three octahedra by a heavy halogen atom explains the results of NMR and EXAFS analysis.
- Krahl, Thoralf,Kemnitz, Erhard
-
p. 6653 - 6656
(2007/10/03)
-
- Characterisation of the tetrahalophosphonium cations PBrnI4 - n+ (0 ≤ n ≤ 4) by 31P MAS NMR, IR and Raman spectroscopy and the crystal structures of PI4+AlCl4-, PI4+AlBr4- and PI4+GaI4-
-
The novel tetrahalophosphonium salts PBr4+AsF6-, PI4+AlCl4- and PI4+EBr4- (E = Al, Ga) have been synthesised. A variety of solid complexes containing PBr4+ (e.g. PBr4+AsF6-, PBr4+AlBr4- PBr4+GaBr4-), PI4+ (e.g. PI4+AlCl4-, PI4+AlBr4-, PI4+GaBr4-) or the mixed species PBrnI4 - n+ (0 ≤ n ≤ 4, containing AlBr4-, GaBr4-, AsF6- or SbF6-) have been studied by solid-state 31P MAS NMR and vibrational spectroscopy. The influence of the counter-ion on the chemical shift and the vibrational frequencies are discussed. The crystal structures of PI4+AlCl4-, PI4+AlBr4- and PI4+GaI4- are reported. Evidence for the existence of the hitherto unknown mixed bromoiodophosphonium cations PBr3I+, PBr2I2+ and PBrI3+ has been confirmed by spin-orbit corrected density functional calculations of isotropic 31P chemical shifts for PBrnI4 - n+.
- Aubauer,Kaupp,Klapoetke,Noeth,Piotrowski,Schnick,Senker,Suter
-
p. 1880 - 1889
(2007/10/03)
-
- The formation of HAlX2 (X = Cl, Br) in the thermolysis of intramolecularly coordinated alanes Me2N(CH2)3AlX2: A matrix isolation study
-
High-vacuum thermolyses of the intramolecularly coordinated alanes Me2N(CH2)3AlX2 with X = Cl, Br (1, 2) were investigated with matrix isolation techniques. Among the products, which were identified with IR spectroscopy, ab initio calculations, and known literature data, are monomeric HAlCl2 and HAlBr2. The experimental vibrational frequencies of these hydrides matches well the calculated harmonic frequencies at the MP2(fc)/6-311G+(2d, p) and B3LYP/6-311G+(2d, p) level of theory. Beside the monomeric HAlX2, the argon matrices of the thermolysis experiments contained CH4, HCN, H2C=CH2, H2C=NMe, [H2CCHCH2]?, H2C=CHCH3, and AlXn (n = 1-3; X = Cl or Br).
- Mueller, Jens,Wittig, Bob
-
p. 1807 - 1810
(2008/10/08)
-
- The Preparation and Characterisation by Raman Spectroscopy of AsBr4+AsF6- containing the Tetrabromoarsenic (V) Cation
-
The thermodynamically unstable AsBr4+AsF6- was prepared by the reaction of AsBr3, Br2, and AsF5 at low temperatures, and characterised by Raman spectroscopy.
- Klapoetke, Thomas,Passmore, Jack,Awere, Edward G.
-
p. 1426 - 1427
(2007/10/02)
-
- Sinthesis and High-Pressure Behaviour of Quaternary Chalcogenide Halides M2M'X3Y (M = Zn, Cd; M' = Al, Ga, In; X = Se, Te; Y = Cl, Br, I)
-
Quaternary chalcogenide halides M2M'X3Y (M = Zn, Cd; M' = Al, Ga, In; X = Se, Te; Y = Cl, Br, I) can be synthesized by heating stoichiometric amounts of the binary components MX, MY2, and M'2X3 in evacuated sealed quartz ampoules.In the case of aluminium and gallium compounds, a mixture of the M' and X elements rather than the binary compounds has been used.The products are typical tetrahedral compounds, crystallizing with either the defect wurtzite-type or the defect zinc-blende-type structure.At 25 kbar, and 1400 deg C, Cd2InSe3Cl, Cd2InSe3Br, and Cd2InSe3I transform from the defect wurtzite-type structure to quenchable high-pressure phases with defect NaCl-type structure.The retransformation to the ambient-pressure phases proceeds via intermediates having the defect zinc-blende-type structure.Some aspects of the apparent nonstoichiometry in the high-pressure phases are discussed. - Keywords: Quaternary Chalcogenide Halides, Synthesis, Crystal Structure, High-Pressure Reactions
- Range, Klaus-Juergen,Handrick, Karin
-
p. 153 - 158
(2007/10/02)
-
- The standard enthalpies of formation of crystalline aluminium(III) bromide and aluminium(III) iodide
-
The enthalpies of solution of crystalline AlCl3 and KBr were measured successively in one portion of 3.5 mol dm-3 HCl solution as well as AlBr3 and KCl in another.The measurements were carried out in a 100 cm3 reaction vessel of the isoperibol calorimeter LKB-8700.The standard enthalpy of the resuming reaction: AlCl3(c) + 3 KBr(c) = AlBr3(c) + 3 KCl(c), was found to be ΔH0r(298.15 K) = (63.4 +/- 1.3) kJ mol-1 which leads to ΔH0f(AlBr3, c, 298.15 K) = (-512.6 +/- 1.9) kJ mol-1.The same measurements were carried out for AlCl3 and KI and for AlI3 and KCl.The standard enthalpy of reaction: AlCl3(c) + 3 KI(c) = AlI3(c) + 3 KCl(c), was found to be ΔH0r(298.15 K) = (80.1 +/- 1.4) kJ mol-1 which leads to ΔH0f(AlI3, c, 298.15 K) = (-302.9 +/- 2.0) kJ mol-1.
- Efimov, M. E.,Kislova, G. N.,Medvedev, V. A.
-
p. 1149 - 1156
(2007/10/02)
-