The phosphoryl and the carbonyl group as hydrogen bond acceptors

Abstract

Formation constants for the hydrogen-bonded complexes between phenol (donor) and selected carbonyl or phosphoryl compounds (acceptors) were determined from IR Δν shifts. The P=O group is about two orders of magnitude stronger as an acceptor than the C=O group, but no evidence for the enolization of a β-diphosphoryl system was found. The IR absorption band of the phosphoryl group (νP=O) showed weak response to the involvement in the hydrogen bonding, and the shifts of the donor molecule (νOH) provide a better measure of the formation constants. Key words: carbonyl and phosphoryl groups as hydrogen bond acceptors, enolization of a β-difunctional system, determination of Kassoc from the IR Δνshifts.