scholarly journals Supported and inserted monomeric niobium oxide species on/in silica: a molecular picture

2015 ◽  
Vol 17 (34) ◽  
pp. 22402-22411 ◽  
Author(s):  
Diana C. Tranca ◽  
Anna Wojtaszek-Gurdak ◽  
Maria Ziolek ◽  
Frederik Tielens
Keyword(s):  
Experimental Data ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Niobium Oxide ◽  
Spectroscopic Properties ◽  
Oxide Catalysts ◽  
Molecular Structures ◽  
Molecular Picture

The geometry, energetic, and spectroscopic properties of molecular structures of silica-supported niobium oxide catalysts are studied using periodic density functional calculations (DFT) and compared with experimental data.

A combined QM/MM study of ligand substitution enthalpies in the L2Fe(CO)3, RuCpL2Cl, and RuCp*L2Cl systems

1998 ◽  
Vol 76 (10) ◽  
pp. 1457-1466 ◽  
Author(s):  
Luigi Cavallo ◽  
Tom K Woo ◽  
Tom Ziegler
Keyword(s):  
Experimental Data ◽  
Key Words ◽  
Molecular Mechanics ◽  
Density Functional ◽  
Ligand Substitution ◽  
Organometallic Complexes ◽  
Molecular Structures ◽  
Substitution Reactions ◽  
Good Accord ◽  
Steric Influence

A combined density functional and molecular mechanics approach (QM/MM) has been validated in a study of the substitution reactions: (i) (PH3)2Fe(CO)3 + 2ER3 ⇆ (ER3)2Fe(CO)3 + 2PH3(ER3 = PMe3, PEt3, PMePh2, PPh3, PCyPh2, PiPr3, PBz3, PCy3, AsEt3, AsPh3); and (ii) Cp'Ru(PH3)2Cl + 2ER3 ⇆ Cp'Ru(ER3)2Cl + 2PH3 (Cp' = C5H5, C5(CH3)5; ER3 = PMe3, PEt3, PnBu3, PMe2Ph, PMePh2, PPh3, AsEt3, P(OMe)3, P(OPh)3, P(OCH2)3CEt). The steric influence of the R substituents on the substitution enthalpies correlates well with experimental data. The combined QM/MM approach is also able to afford molecular structures in good accord with experimental estimates. Key words: combined QM/MM, ligand substitutions, organometallic complexes.

Density Functional calculations for some hydrogen-bonded systems. Influence of a dielectric surrounding

1995 ◽  
Vol 73 (5) ◽  
pp. 710-715 ◽  
Author(s):  
Y. Jeanvoine ◽  
F. Bohr ◽  
M.F. Ruiz-López
Keyword(s):  
Experimental Data ◽  
Density Functional Calculations ◽  
Liquid State ◽  
Density Functional ◽  
Cooperative Effect ◽  
Bond Density ◽  
Hydrogen Bonded Systems ◽  
Good Agreement ◽  
Dielectric Environment ◽  
Hydrogen Bonded

We present Density Functional calculations for hydrogen-bonded systems with small, medium, and large association energies, in a vacuum and in a dielectric environment. The results are in reasonably good agreement with accurate ab initio results and available experimental data. They confirm that DFT is very promising for modeling liquid state properties. Keywords: hydrogen bond, Density Functional, cooperative effect, liquid state.

Electronic structure of S-nitrosothiols from sulfur K-edge X-ray absorption spectroscopy

2011 ◽  
Vol 89 (2) ◽  
pp. 93-97 ◽  
Author(s):  
Vlad Martin-Diaconescu ◽  
Inna Perepichka ◽  
D. Scott Bohle ◽  
Pierre Kennepohl
Keyword(s):  
Experimental Data ◽  
Electronic Structure ◽  
Absorption Spectroscopy ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Computational Models ◽  
Nitroso Group ◽  
X Ray ◽  
X Ray Absorption

Sulfur K-edge X-ray absorption spectroscopy (S K-edge XAS) was applied to investigate the electronic structure of primary and tertiary S-nitrosothiols. Our experimental data, supported by density functional calculations, indicate that changes at Cα affect the S-nitroso group through both inductive and direct orbital effects. Furthermore, our data are consistent with a weakening of the S–N bond in tertiary S-nitrosothiols as compared to their primary S-nitroso analogues. These results support existing computational models and suggest that the reactivity of S-nitrosothiols is not dominated by the electronics of the S–N bond.

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