15453-67-5Relevant academic research and scientific papers
Isotope Effects in the Nuclear Magnetic Resonance Spectra of Mixed Aqua Complexes of AlIII
Akitt, J. W.,Howart, Oliver W.
, (1989)
Alumminium-27 n.m.r. measurements of the isotope shifts caused by the substituton of hydrogen by deuterium in the water ligands of the hydrate complexes + and 6-n>3+, 0 /= n /= 6, are reported in a
Distinct water-exchange mechanisms for trinuclear transition-metal clusters
Houston, Jacqueline R.,Richens, David T.,Casey, William H.
, p. 7962 - 7967 (2006)
Mechanisms for water exchange from the bioxo-capped M-M-bonded trinuclear clusters, [M3(μ3-O)2(μ-O 2CCH3)6-(OH2)3] 2+ [M = Mo(IV) and W(IV)], were investigated using high-pressure 17O NMR and compared to our previous work on a similar Rh(III) trimer. Reaction rates decrease by more than a factor of 2 when pressure is increased from 6 to 250 MPa for the Mo(IV) trimer, while exchange rates increase by less than a factor of 1.2 (10-229 MPa) for the W(IV) trimer. From the pressure dependence of the reaction rate, activation volumes (ΔV ?) were calculated to be ΔC? = +8.0 (±0.4) cm3 mol-1 and ΔC? = -1.9 (±0.2) cm3 mol-1 for the Mo(IV) cluster and W(IV) cluster, respectively, which is the largest difference (～10 cm 3 mol-1) in activation volumes for any pair of 4d-5d (and 3d-4d) transition metal species located within the same group of the periodic table. If we interpret these activation volumes in terms of Swaddle's semiempirical model, which he established for simple octahedral monomers (Associative (A) = ΔV? ≈ -13; Interchange (I) = ΔV? ≈ 0; or Dissociative (D) = ΔV ? ≈ +13), our results suggest that water exchange follows a dissociative-interchange (Id) mechanism for the Mo(IV) cluster and an associative-interchange (Ia) activation mode for the W(IV) trimer. These volumes exhibit a unique changeover in the water-exchange mechanism despite considerable similarities in molecular structure and reactivity. This changeover could provide a standard for computational simulations of ligand-exchange pathways in molecules that are more complicated than monomers.
Aluminium-27 Nuclear Magnetic Resonance Studies of the Hydrolysis of Aluminium(III). Part 5. Slow Hydrolysis using Aluminium Metal
Akitt, J. W.,Farthing, Alan
, p. 1624 - 1628 (1981)
Aluminium-27 n.m.r. spectra are presented of solutions prepared by the relatively slow hydrolysis of AlCl3 solutions with aluminium metal in the presence of mercury.The ways in which the spectra change with temperature or concentration are described and changes are also noted to occur as a function of magnetic field strength.It is not possible to give an unequivocal answer as to what is the nature of the species present in these solutions but there seem to be a variety of ions present which are quite easily interconvertible, contain octahedrally co-ordinated Al, and are associated in some way with fragments which resemble (7+) (Al13) since some tetrahedrally co-ordinated Al always seems to be present.Thus it is suggested that structures may consist of partial Al13 units with octahedral units disposed as flexible chains and/or forming cross links.
X-ray absorption spectroscopy of aqueous aluminum-organic complexes
Hay, Michael B.,Myneni, Satish C. B.
, p. 6138 - 6148 (2010/09/10)
Aqueous-phase X-ray absorption near-edge structure (XANES) spectra were collected on dissolved Al complexes with organic ligands, including desferrioxamine B, EDTA, acetohydroxamate, malate, oxalate, and salicylate. Spectral interpretations were made using the density functional theory-based modeling package StoBe. The goals of this work were to study the geometric and electronic structural characteristics of these complexes relative to Al(H 2O)63+ and to examine the utility of the aqueous Al XANES technique as a tool for probing Al speciation and structure. In the case of EDTA, aqueous Fourier-transform infrared spectroscopy was also used to corroborate the structures of the Al(EDTA)- and AlOH(EDTA) 2- complexes. Synthetic XANES spectra calculated with StoBe reproduced the observed spectral differences between Al(H2O) 63+, Al(dfoB)+, and Al(EDTA)-. The narrower XANES feature observed for Al(dfoB)+ relative to Al(H 2O)63+ can be attributed to a weaker splitting of the Al 3p - O 2p interactions in the former, while Al(EDTA)- exhibits split Al 3p - ligand interactions that likely result from the mixed O/N coordination. In complexes with mixed aqua/organic-oxygen ligation (Al-acetohydroxamate, Al-malate, Al-oxalate, and Al-salicylate), spectra exhibit linear, systematic changes in peak width as a function of H2O to organic ligand ratio in the Al coordination sphere. These results highlight the sensitivity of the aqueous Al K-edge XANES spectrum to coordination environment and demonstrate its utility as an experimental probe for future studies of Al speciation in complex solutions.
Etching AlAs with HF for epitaxial lift-off applications
Voncken,Schermer,Van Niftrik,Bauhuis,Mulder,Larsen,Peters,De Bruin,Klaassen,Kelly
, p. G347-G352 (2008/10/09)
The epitaxial lift-off process allows the separation of a thin layer of III/V material from the substrate by selective etching of an intermediate AlAs layer with HF In a theory proposed for this process, it was assumed that for every mole of AIAs dissolved three moles of H2 gas are formed. In order to verify this assumption the reaction mechanism and stoichiometry were investigated in the present work. The solid, solution and gaseous reaction products of the etch process have been examined by a number of techniques, It was found that aluminum fluoride is formed, both in the solid form as well as in solution. Furthermore, instead of H2 arsine (AsH3) is formed in the etch process. Some oxygen-related arsenic compounds like AsO, AsOH, and AsO2 have also been detected with gas chromatography/mass spectroscopy. The presence of oxygen in the etching environment accelerates the etching process, while a total absence of oxygen resulted in the process coming to a premature halt. It is argued that, in the absence of oxygen, the etching surface is stabilized, possibly by the sparingly soluble A1F3 or by solid arsenic.
A new bis(3-hydroxy-4-pyridinone)-IDA derivative as a potential therapeutic chelating agent. Synthesis, metal-complexation and biological assays
Santos, M. Amelia,Gama, Sofia,Gano, Lurdes,Cantinho, Guilhermina,Farkas, Etelka
, p. 3772 - 3781 (2007/10/03)
A new bis(3-hydroxy-4-pyridinone) derivative of iminodiacetic acid, imino-bis(acetyl(1-(3′-aminopropyl)-3-hydroxy2-methyl-4-pyridinone)), IDAPr(3,4-HP)2, has been prepared and studied in its interaction with a set of hard metal ions. This tetradentate ligand presents a much higher chelating efficiency for trivalent hard metal ions (Fe, Ga, Al) than the monodentate derivative Deferriprone, namely at the diluted conditions prevailing in physiological conditions and at low clinical doses. A similar behaviour was also observed for the complexation with Zn(II) but at a significantly lower extent. This compound presents a moderate hydrophilic character at physiological pH (log D = -1.72). In vivo assays showed much more rapid clearance of 67Ga from most tissues of metal-loaded mice than the drug Deferriprone and the radioactivity excretion occurs mostly through the kidneys. Therefore, results from in vitro and in vivo studies indicated good perspectives for this compound to be a potential decorporating agent for hard metal ions in overload situations without depletion of essential metal ions such as zinc.
Aluminum-27 nuclear magnetic resonance study of aluminum(III) interactions with carboxylate ligands
Karlik,Tarien,Elgavish,Eichhorn
, p. 525 - 529 (2008/10/08)
Aluminum-27 NMR in high field has been employed in aqueous solution, at 10 mM concentration, for the study of the interactions of Al(III) with citrate, lactate, and ethylenediaminetetraacetate (EDTA). In the reaction with lactate, slow-exchange phenomena make possible the observation of distinct peaks for hydrated Al(III), 1:1 and 1:3 Al-lactate complexes, as well as mixed aquo-lactato and hydroxo-lactato complexes. Increasing pH leads to substitution of water in the Al(III) coordination sphere by lactate and eventually to substitution of lactate by hydroxide. A 1:3 Al(III)-lactate complex produced in the presence of excess lactate remains in a metastable condition and does not readily dissociate when more Al(III) is added. Increased pH has similar effects on the reaction of Al(III) with citrate, but the reaction with EDTA leads to only one peak that corresponds to a very stable complex; apparently no mixed aquo-EDTA or hydroxo-EDTA complexes can be observed.
