Deuterium isotope effects on ¹⁷O chemical shifts of intramolecularly hydrogen bonded systems

Deuterium isotope effects on 17O chemical shifts are studied in a series of intramolecularly hydrogen bonded o-hydroxy acyl aromatics and β- diketones. Geometries and chemical shifts are calculated using DFT ab initio methods. Relationships between hydrogen bond strength represented as either R(O ··· O), R(O-H) or R(O ··· H) and the experimental parameters, 5Δ17O(OD) and δ17O are demonstrated for non-tautomeric compounds. These plots do also provide a method for establishing tautomerism in new compounds. 5Δ17O(OD) as well as δ17O are found to be dominated by hydrogen bonding in terms of R(O-H) or R(O ··· H) distances and not influenced very much by the R(O ··· O) distance.