Robert L. Carroll

On the ΔH and ΔS of metal ion interaction with substituted methylene diphosphonates

Abstract The Ca2+ and Mg2+ complexing constants with a series of substituted methylene diphosphonates have been determined at 25° in 0·5 M tetramethylammonium chloride. The enthalpies of Ca2+, Li+, Na+, and K+ complexing by substituted methylene diphosphonates have been measured calorimetrically. The Δ S values of complexing of a given metal ion is shown to be remarkably constant with diphosphanates, and proportional to Z 2 r . Variations in the Δ G values of complexing are attributed to differences in the Δ H term.