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A theoretical study on the gas phase reactions of the anions NbO3-, NbO5-, and NbO2(OH)2- with H2O and O2.
Autorzy
Rok wydania
2004
Czasopismo
Journal of Physical Chemistry A
Numer woluminu
108
Strony
10850-10860
DOI
10.1021/jp047229b
Kolekcja
Język
Angielski
Typ publikacji
Artykuł
The potential energy surfaces at the singlet (s) and the triplet (t) electronic states associated with the gas-phase ion/molecule reactions of NbO3-, NbO5-, and NbO2(OH)2- with H2O and O2 have been investigated by means of DFT calculations at the B3LYP level. An analysis of the results points out that the most favorable reactive channel comprises s-NbO3- reacting with H2O to give an ion−molecule complex s-NbO3(H2O)- without a barrier. From this minima, an intramolecular hydrogen transfer takes place between the incoming water molecule and an oxygen atom of the NbO3- fragment to render the most stable minimum, s-NbO2(OH)2-. This oxyhydroxide system reacts with O2 along a barrierless process to obtain the triplet t-NbO4(OH)2--A intermediate, and the crossing point, CP1, between s and t electronic states has been characterized. The next step is the hydrogen-transfer process between the oxygen atom of a hydroxyl group and the one adjacent oxygen atom to render a minimum with the two OH groups near each other, t-NbO4(OH)2--B. From this point, the last hydrogen migration takes place, to obtain the product complex, t-NbO5(H2O)-, that can be connected with the singlet separated products, s-NbO5- and H2O. Therefore, a second crossing point, CP2, has been localized. The nature of the chemical bonding of the key minima (NbO3-, NbO2(OH)2-, NbO4(OH)2--B, and NbO5-) in both electronic states of the reaction and an interaction with O2 has been studied by topological analysis of Becke−Edgecombe electron-localization function (ELF) and atoms-in-molecules (AIM) methodology. The niobium−oxygen interactions are characterized as unshared-electron (ionic) interactions and some oxygen−oxygen interactions as protocovalent bonds.
Słowa kluczowe
Oxygen, Chemical reactions, Electron density, Potential energy, Molecules
Adres publiczny
https://doi.org/10.1021/jp047229b
Strona internetowa wydawcy
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