Molecular structure of complexes with a bifurcated hydrogen bond. 5. Dimers of 3-hydroxy-2-methyl-4-pyrone in inert media

Abstract

According to the data from IR spectroscopy and quantum-chemical calculations (B3LYP/6-31G**, B3LYP/6-311G*), in the vapor and in dichloroethane the synperiplanar conformer of 3-hydroxy-2-methyl-4-pyrone (maltol) exists in equilibrium with two types of dimers. The hydrogen atom of the hydroxy group of one them participates in the formation of a three-center bifurcated hydrogen bond. The second isomer is formed by means of two such H bonds, the intramolecular component of which is substantially weakened while the intermolecular component is so strong that it approximates in character to a two-center hydrogen bond.

Stereoactive lone pair of electrons on bismuth(III): tris(3-hydroxy- 2-methyl-4H-pyran-4-onato)bismuth(III)

“…25 Disappearance of the absorption band ν(О-Н) at 3240 cm -1 , assigned to maltol hydroxyl, is indicative of the hydroxyl group deprotonation and its coordination with respect to bismuth. The appearance of the bands at 445 cm -1 and 251 cm -1 proves the availability of the metal-oxygen bond.…”

Bifurcate Hydrogen Bonds. Interaction of Intramolecularly H-Bonded Systems with Lewis Bases

“…From the aforementioned four possibilities of the formation of the bifurcate hydrogen bond the first three are the most theoretically studied . For identification of BHB of the type 4 only the truncated (that is, without analysis of its angular characteristics) geometric criteria were invoked rather than the well approved quantum topological AIM approach . At the same time, the formation of a three-centered hydrogen bond of the type 4 is feasible under the conditions of specific solvation of the intramolecularly H-bonded species with basic solvents.…”