author = "Alkorta, Ibon"

Encontrado 823 documentos, página mostrada 1 de 83

Cation dinitrogen complexes [N2⋯X⋯N2]+, X+=H+, Li+, Na+, Be2+, Mg2+

Description: The complexes of dinitrogen with five cations (H+, Li+, Na+, Be2+ and Mg2+) up to four N2 molecules have been calculated at the MP2/6-311++G(d,p) level. Energetic and geometric aspects have been determined together with absolute shieldings (GIAO). The atoms in molecules methodology has been used to ...
Language(s): Inglés

The relative stability of pyridinium and 1,7-diaza[12]annulenium quaternary salts

Description: Theoretical calculations (energies and chemical shifts) at the B3LYP/6-311++G(d,p) level confirm that the compounds described as 1,7-diaza[12]annulenium quaternary salts are in fact pyridinium quaternary salts. © 2008 Elsevier Ltd. All rights reserved. , Peer Reviewed
Language(s): Inglés

Polyynes vs. cumulenes: Their possible use as molecular wires

Description: Polyynes and cumulenes from 2-12 atoms have been calculated at the B3LYP/6-311++G** level and their energies compared using an isodesmic reaction. The chain length has been modeled empirically affording an equation that predicts substantial variation for long chains. © 2005 Springer Science+Business...
Language(s): Inglés

Theoretical estimation of the annular tautomerism of indazoles

Description: Theoretical calculations at semi-empirical AM1 and density functional B3LYP/6-31G* levels were carried out on 52 NH-indazoles. Although in most cases the 1H-tautomer is the most stable, we found several indazoles for which the 2H-tautomer is more stable than the 1H-tautomer. The differences in energ...
Language(s): Inglés

Prototropic tautomerism of 5-aryloxy-1(2)H-tetrazoles

Description: The structure of 5-(2,6-dimethylphenoxy)-1H- and 2H-tetrazoles together with those of 5-(2,6-diisopropyl-phenoxy)-1H and 2H-tetrazoles have been theoretically studied including absolute shieldings and energies. The conclusion of these studies is that a slow tautomerism between 1H- and 2H-tetrazoles ...
Language(s): Inglés

A computational study of the conformation of heterocyclic systems related to biphenyl

Description: The conformation of nine N,N′-linked heterocycles including pyrrole, carbazole, 4H-1,2,4-triazole, pyrazole, pyridinium and 4-pyridone has been explored (minima and transition states) at the B3LYP/6-31G(d) level. Besides, six conformationally restricted molecules belonging to the same series have be...
Language(s): Inglés

An ab initio study of the proton transfer and tautomerization processes in hydroxycarbene

Description: We have investigated the hydrogen-bonded complexes formed by hydroxycarbene in trans configuration at MP2 and CCSD computational levels. In addition, these complexes have been used as starting point in the potential tautomerization of hydroxycarbene to produce formaldehyde. The presence of molecules...
Language(s): Inglés

Conformational analysis of N,N′-dinaphthyl heterocyclic carbenes: Imidazol-2-ylidenes and imidazolin-2-ylidenes

Description: The paths connecting the stationary points of tesseract (four-dimensional hypercube) have beenexplored. The minimum energy conformations and the different transition states of N,N0-dinaphthyl imidazol-2- ylidenes and imidazolin-2-ylidenes have been calculated. The available experimental results were...
Language(s): Inglés

Modeling the allosteric effect: Modification of the tautomerism by intermolecular interactions and extension to molecular wires

Description: B3LYP/6-31G(d) and B3LYP/6-311++ G(d,p) calculations were carried out on quinolone and its four azaderivatives (15 tautomers), five wire models (10 tautomers) for proton transfer formed of anthracenol and azaacridines and the corresponding five crown ethers (ten tautomers) in the anthracenol part. T...
Language(s): Inglés

Encontrado 823 documentos, página mostrada 1 de 83

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