Hydrogen bonding of carbonyl, ether, and ester oxygen atoms with alkanol hydroxyl groups

✍ Scribed by Lommerse, Jos P. M.; Price, Sarah L.; Taylor, Robin

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 466 KB
• Volume: 18
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/(sici)1096-987x(19970430)18:6<757::aid-jcc3>3.0.co;2-r

✦ Synopsis

An attractive way to study intermolecular hydrogen bonding is to combine analysis of experimental crystallographic data with ab initio᎐based Ž . energy calculations. Using the Cambridge Structural Database CSD , a Ž . distributed multipole analysis DMA -based description of the electrostatic Ž . energy, and intermolecular perturbation theory IMPT calculations, hydrogen bonding between donor alkanol hydroxyl groups and oxygen acceptor atoms in ketone, ether, and ester functional groups is characterized. The presence and absence of lone pair directionality to carbonyl and ether or ester oxygens, respectively, can be explained in terms of favored electrostatic energies, the major attractive contribution in hydrogen bonding. A hydrogen bond in its optimum geometry is only slightly stronger when formed to a ketone group than to an ether group. Hydrogen bonds formed to carbonyl groups have similar properties in a ketone or ester, but the ester O 2 differs from an ether oxygen due to various environmental effects rather than a change in its intrinsic properties.

Ž . For E -ester oxygens, there are few hydrogen bonds found in the CSD because of the competition with the adjacent carbonyl group, but the interaction energies 2 Ž . are similar to an ether. Hydrogen bonds to O of Z -esters are destabilized by the repulsive electrostatic interaction with the carbonyl group. The relative abundance of nonlinear hydrogen bonds found in the CSD can be explained by geometrical factors, and is also due to environmental effects producing slightly stronger intermolecular interaction energies for an off-linear geometry.