Enlaces de hidrógeno bifuncionales >O...H(H)O...H-C en el complejo tetrahidropirano-agua. Un estudio teórico.

ANGELINA, EMILIO; VALLEJOS, MARGARITA; PERUCHENA, NELIDA

FACENA

Facultad de Ciencias Exactas y naturales y Agrimensura UNNE

Año: 2007 vol. XXII p. 7 - 32

0325-4216

In this work the bifunctional hydrogen bond, HBbif, in THF-H2O complex, in gas phase, is studied within the framework of the Density Functional Theory. The electronic structure calculations were carried out using the B3LYP functional hybrid and the 6-31G** basis set. In order to make in deep form a electronic study about intra and intermolecular interactions involved in the bifunctional HB, the Charge Transfer Analysis on the basis of Natural Bond Orbital, NBO, was carried out in conjunction with the Atoms in Molecules, AIM, theory. Besides to verify the formation of thebifunctional hydrogen bonds in THF-H2O complex, where an only water molecule takes part like hydrogen donor (Ow-Hw(b)…OTHF) and hydrogen acceptor ( C4-H4sa…Ow) in the formation of a proper (strong or moderate strong HB) and another improper hydrogen bond (weak), the cooperative effects between the proper and improper hydrogen bonds, are analyzed. The results show that the principal characteristic in THF-H20 complex is the redistribution of the charge density over the whole molecule. In other words, the modifications on the remote parts, (Z), in Z-X-H…Y according to Hobza characteristic of the improper HB, occurs in both proper and improper HB, as a consequence of  intramolecular/intermolecular donor-acceptor effects.In this work the bifunctional hydrogen bond, HBbif, in THF-H2O complex, in gas phase, is studied within the framework of the Density Functional Theory. The electronic structure calculations were carried out using the B3LYP functional hybrid and the 6-31G** basis set. In order to make in deep form a electronic study about intra and intermolecular interactions involved in the bifunctional HB, the Charge Transfer Analysis on the basis of Natural Bond Orbital, NBO, was carried out in conjunction with the Atoms in Molecules, AIM, theory. Besides to verify the formation of thebifunctional hydrogen bonds in THF-H2O complex, where an only water molecule takes part like hydrogen donor (Ow-Hw(b)…OTHF) and hydrogen acceptor ( C4-H4sa…Ow) in the formation of a proper (strong or moderate strong HB) and another improper hydrogen bond (weak), the cooperative effects between the proper and improper hydrogen bonds, are analyzed. The results show that the principal characteristic in THF-H20 complex is the redistribution of the charge density over the whole molecule. In other words, the modifications on the remote parts, (Z), in Z-X-H…Y according to Hobza characteristic of the improper HB, occurs in both proper and improper HB, as a consequence of  intramolecular/intermolecular donor-acceptor effects.