Jpm. Lommerse et al., HYDROGEN-BONDING OF CARBONYL, ETHER, AND ESTER OXYGEN-ATOMS WITH ALKANOL HYDROXYL-GROUPS, Journal of computational chemistry, 18(6), 1997, pp. 757-774
An attractive way to study intermolecular hydrogen bonding is to combi
ne analysis of experimental crystallographic data with ab initio-based
energy calculations. Using the Cambridge Structural Database (CSD), a
distributed multipole analysis (DMA)-based description of the electro
static energy, and intermolecular perturbation theory (IMPT) calculati
ons, hydrogen bonding between donor alkanol hydroxyl groups and oxygen
acceptor atoms in ketone, ether, and ester functional groups is chara
cterized. The presence and absence of lone pair directionality to carb
onyl and ether or ester oxygens, respectively, can be explained in ter
ms of favored electrostatic energies, the major attractive contributio
n in hydrogen bonding. A hydrogen bond in its optimum geometry is only
slightly stronger when formed to a ketone group than to an ether grou
p. 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 intrinsi
c properties. For (E)-ester oxygens, there are few hydrogen bonds foun
d in the CSD because of the competition with the adjacent carbonyl gro
up, but the interaction energies are similar to an ether. Hydrogen bon
ds to O-2 of (Z)-esters are destabilized by the repulsive electrostati
c interaction with the carbonyl group. The relative abundance of nonli
near hydrogen bonds found in the CSD can be explained by geometrical f
actors, and is also due to environmental effects producing slightly st
ronger intermolecular interaction energies for an off-linear geometry.
(C) 1997 by John Wiley & Sons, Inc.