SOLVATION AND METAL-ION EFFECTS ON STRUCTURE AND REACTIVITY OF PHOSPHORYL COMPOUNDS .3. CONFORMATIONAL-ANALYSIS OF 2-SUBSTITUTED ALKYLPHOSPHONATES BY PHOSPHORUS-31-CARBON-13 COUPLING-CONSTANTS

One- and three-bond P,C coupling constants in the phosphonate skeleton of dimethyl esters of 2-hydroxy (or 2-methoxy) alkylphosphonic acids were determined from C-13 NMR spectra recorded in various solvents and in the presence of metal ions. The results confirmed earlier conclusi ons about the intramolecular attractive interactions between the OH (O Me) and the phosphoryl groups, enhanced by the complexation with Na+ o r Mg2+ ions. Reasonable correlation between the (3)J(P,C) values and t he population of the conformer involving the trans orientation of the phosphonate group and the C-3 carbon atom was obtained.