SYNTHESIS AND CHARACTERIZATION OF METAL COMPLEXES OF P,P′-DI[3-(TRIMETHYLSILYL)-1-PROPYL] METHYLENEDIPHOSPHONIC ACID

ABSTRACT

The silicon-substituted diphosphonic acid P,P′-di[3-(trimethyl-silyl)-1-propyl] methylenediphosphonic acid, H₂DTMSP-[MDP], reacts with metal nitrates in methanol to form complexes M₂(DTMSP[MDP])₃ for M˭Fe, Eu and Yb and M(DTMSP[MDP])₂ for M˭Th. The sodium salt, Na₂-(DTMSP[MDP]), forms upon neutralization of H₂DTMSP-[MDP] with NaOH. The calcium salt, Ca(DTMSP[MDP]), forms upon addition of the aqueous metal nitrate to an equivalent amount of the neutralized ligand in methanol. Elemental analysis, infrared spectroscopy and magnetic susceptibility measurements were used to characterize the compounds. Frequency shifts in the asymmetric and symmetric POO⁻ stretching bands of the Fe, Eu, Yb and Th compounds indicate symmetrical coordination of the phosphonate groups through chelate and/or bridging interactions. The frequency difference between these stretching bands becomes smaller as the ionic potential (e/r) of the metal ion increases.

ACKNOWLEDGMENTS

The authors thank Marcos H. Grimsditch and Sherrif Uram for use of the Bruker 98 vacuum FT-IR interferometer and help in recording the spectra. The authors also thank Dominique C. Stepinski for her help in preparing the ligand. This work was performed under the auspices of the Environmental Sciences Program of the Offices of Sciences and Environmental Management, U. S. Department of Energy, under grant number DE-FG07-98ER14928 (LUC) and contract number W-31-109-ENG-38 (ANL).