NUCLEAR-MAGNETIC-RESONANCE STUDIES OF 4-HYDROXYPIPERIDINOMETHYLPHOSPHONIC ACID AND ITS POLYOXOMOLYBDATE CONJUGATES

The pD behaviour of 4-hydroxypiperidinomethylphosphonic acid has been investigated using multinuclear NMR (H-1, C-13 and P-31) techniques in D2O solvent. On deuteriation, H-1, C-13 and P-31 signals for two deut eriated isomers were observed. with the 4-hydroxy group occupying eith er an axial or equatorial position. The interaction of this compound w ith molybdate anion as the pH and temperature of the solution were var ied was investigated using P-31 NMR spectroscopy The spectra revealed the formation of several phosphonomolybdate conjugates, one of which c an be assigned as the pentamolybdodiphosphonate. Isomerism of the conj ugate was also evident. Conversions between several phosphorus-contain ing entities occurred at rates detectable; on the P-31 NMR time-scale providing evidence as to the exchange routes.