COPPER(II) COMPLEXES OF N-(PHOSPHONOMETHYL)GLYCINE IN AQUEOUS-SOLUTION - A THERMODYNAMIC AND SPECTROPHOTOMETRIC STUDY

Copper(II) complexes with the herbicide N-(phosphonomethyl)glycine (gl yphosate) have been investigated in aqueous solution by means of pH-me tric measurements at different temperatures, 5 less than or equal to T less than or equal to 45 degrees C, calorimetry and visible spectroph otometry. Potentiometric data, at all the considered temperatures in t he range 2.5 less than or equal to pH less than or equal to 10.5, can be explained assuming the formation of the species CuLH0, CuL-, CuLH-1 2-, CuL2-4- and Cu2L+ By using thermodynamic data and calculated elect ronic spectra for each complex a structural definition is proposed for the different species. Copper(II)-glyphosate complexes are quite stab le and must be taken into account in the speciation of natural fluids. (C) 1997 Elsevier Science B.V.