scholarly journals Density functional theory characterization of the structures of H3AsO3 and H3AsO4 adsorption complexes on ferrihydrite

2018 ◽  
Vol 20 (6) ◽  
pp. 977-987 ◽  
Author(s):  
Nelson Y. Dzade ◽  
Nora H. de Leeuw
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Aqueous Systems ◽  
Functional Theory ◽  
Ferric Oxyhydroxide ◽  
Adsorption Complexes

Reactions occurring at ferric oxyhydroxide surfaces play an important role in controlling arsenic bioavailability and mobility in natural aqueous systems.

Density functional theory (DFT) calculations on the structures and stabilities of [CnO2n+1]2– and [CnO2n+1]X2 polycarbonates containing chainlike (CO2)n units (n = 2–6; X = H or Li)

2011 ◽  
Vol 89 (6) ◽  
pp. 671-687 ◽  
Author(s):  
Pablo J. Bruna ◽  
Friedrich Grein ◽  
Jack Passmore
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Ion Pairs ◽  
Dicarboxylic Acids ◽  
Polarizable Continuum Model ◽  
Weakly Bound ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Weakly Bound Complexes

The structures and stabilities of chainlike (CO2)n (n = 2–6) polycarbonates, where adjacent C atoms are linked by C–O–C bonds, were investigated at the density functional theory (DFT) level (B3PW91/6–311G(2d,p)), including dicarboxylic dianions, [CnO2n+1]2–, and the corresponding acids, [CnO2n+1]H2, and Li salts, [CnO2n+1]Li2. At equilibrium, the most stable systems have Cs, C2, or C2v symmetries. In the gas phase, these dianions are generally metastable with respect to spontaneous ejection of one electron, yet in the presence of counterions they become stabilized, for example, as [CnO2n+1]2–(Li+)2 ion pairs. [CnO2n+1]2– linkages are also stabilized as dicarboxylic acids, [CnO2n+1]H2; we find the latter to have equilibrium conformations of higher symmetry than previously reported in the literature. To the best of our knowledge, none of the [CnO2n+1]X2 (X = Li or H) compounds with n ≥ 2 have been reported in the experimental literature (albeit, the alkyl esters C2O5R2 and C3O7R2 are commercially available). All CO bonds in C2O5X2 to C6O13X2 have single- to double-bond character (≈140–118 pm), indicating that the [CnO2n+1] moieties are held together by strong chemical forces (in contrast to the weakly bound complexes (CO2)n and (CO2)n–, n > 1). Vibrational frequencies were calculated to ensure all conformations were true minima. The IR and Raman intensities show that the high intensity C=O stretching modes (1750 ± 100 cm–1) will help in the spectral characterization of these compounds. Solvation calculations using the polarizable continuum model (PCM) find that C2O52– can be formed via CO32– + CO2 as well as CO3–[Formula: see text], each reaction having ΔG298 < 0 in practically all solvents. This result confirms the experimentally observed large solubility of CO2(g) in molten carbonates, CO3M2 (M = Li, Na, or K). In contrast, starting with n = 2, the reactions [CnO2n+1]2– + CO2 do not proceed spontaneously in any solvent (ΔG298 > 0).

Computational characterization of sodium selenite using density functional theory

2010 ◽  
Vol 17 (4) ◽  
pp. 701-708
Author(s):  
Diana Barraza-Jiménez ◽  
Manuel Alberto Flores-Hidalgo ◽  
Donald H. Galvan ◽  
Esteban Sánchez ◽  
Daniel Glossman-Mitnik
Keyword(s):  
Density Functional Theory ◽  
Sodium Selenite ◽  
Density Functional ◽  
Functional Theory

P—N Bond Length Alterations Monitored by Infrared Absorption and Fourier Transform Raman Spectroscopy in Combination with Density Functional Theory Calculations

2003 ◽  
Vol 57 (8) ◽  
pp. 970-976 ◽  
Author(s):  
M. Bolboaca ◽  
T. Stey ◽  
A. Murso ◽  
D. Stalke ◽  
W. Kiefer
Keyword(s):  
Density Functional Theory ◽  
Fourier Transform ◽  
Density Functional ◽  
Structural Parameters ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Fourier Transform Raman Spectroscopy ◽  
Raman And Infrared Spectroscopy ◽  
Fourier Transform Raman

Fourier transform (FT) Raman and infrared spectroscopy in combination with density functional theory calculations have been applied to the vibrational characterization of the dimeric zinc diphenylphosphanyl(trimethylsilyl)amide complex [(Me3Si)2NZnPh2PNSiMe3]2 and the ortho-metallated species [Li( o-C6H4PPh2NSiMe3)]2·Et2O in relation to their parent starting materials diphenylphosphanyl (trimethylsilyl)amine Ph2P–N(H)SiMe3 and iminophosphorane Ph3P=NSiMe3. The spectroscopic changes evidenced in the spectra were correlated with the structural parameters in order to provide insight as to what extent the P–N bond is affected by the coordination to the metal center. The employment of density functional theory (DFT) calculations in addition to these spectroscopic methods offers the possibility of predicting whether the Lewis-basic imido nitrogen atom is involved in coordination not only in the solid state, but also in the gas phase.

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