Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 2 de 2
Filtrar
Más filtros











Base de datos
Intervalo de año de publicación
1.
Faraday Discuss ; 203: 47-60, 2017 10 13.
Artículo en Inglés | MEDLINE | ID: mdl-28726935

RESUMEN

Halogen bonds involving cationic halogen bond donors and anionic halogen bond acceptors have recently been recognized as being important in stabilizing the crystal structures of many salts. Theoretical characterization of these types of interactions, most importantly in terms of their directionality, has been limited. Here we generate high-quality symmetry adapted perturbation theory potential energy curves of a H3N-C[triple bond, length as m-dash]C-Br+Cl- model system in order to characterize halogen bonds involving charged species, in terms of contributions from electrostatics, exchange, induction, and dispersion, with special emphasis on analyzing contributions that are most responsible for the directionality of these interactions. It is found that, as in the case of neutral halogen bonds, exchange forces are important contributors to the directionality of charged halogen bonds, however, it is also found that induction effects, which contribute little to the stability and directionality of neutral halogen bonds, play a large role in the directionality of halogen bonds involving charged species. Potential energy curves based on the ωB97X-D/def2-TZVP/C-PCM method, which includes an implicit solvation model in order to mimic the effects of the crystal medium, are produced for both the H3N-C[triple bond, length as m-dash]C-Br+Cl- model system and for the 4-bromoaniliniumCl- dimer, which is based on the real 4-bromoanilinium chloride salt, whose crystal structure has been determined experimentally. It is found that, within a crystal-like medium, charged halogen bond are significantly weaker than in the gas phase, having optimum interaction energies up to approximately -20 kcal mol-1.


Asunto(s)
Antipirina/análogos & derivados , Cloruros/química , Halógenos/química , Antipirina/química , Cristalografía por Rayos X , Dimerización , Halogenación , Modelos Moleculares , Teoría Cuántica , Electricidad Estática , Termodinámica
2.
Chemistry ; 22(49): 17690-17695, 2016 Dec 05.
Artículo en Inglés | MEDLINE | ID: mdl-27786398

RESUMEN

Halogen bonds involving an aromatic moiety as an acceptor, otherwise known as R-X⋅⋅⋅π interactions, have increasingly been recognized as being important in materials and in protein-ligand complexes. These types of interactions have been the subject of many recent investigations, but little is known about the ways in which the strengths of R-X⋅⋅⋅π interactions vary as a function of the relative geometries of the interacting pairs. Here we use the accurate CCSD(T) and SAPT2+3δMP2 methods to investigate the potential energy landscapes for systems of HBr, HCCBr, and NCBr complexed with benzene. It is found that only the separation between the complexed molecules have a strong effect on interaction strength while other geometric parameters, such as tilting and shifting R-Br⋅⋅⋅π donor relative to the benzene plane, affect these interactions only mildly. Importantly, it is found that the C6v (T-shaped) configuration is not the global minimum for any of the dimers investigated.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA