Change search
ReferencesLink to record
Permanent link

Direct link
IR and EXAFS Spectroscopic Studies of Glyphosate Protonation and Copper(II) Complexes of Glyphosate in Aqueous Solution
Umeå University, Faculty of Science and Technology, Chemistry.
Umeå University, Faculty of Science and Technology, Chemistry.
2001 (English)In: Inorganic Chemistry, Vol. 40, no 17, 4302-9 p.Article in journal (Refereed) Published
Abstract [en]

The varying degrees of protonation of N-(phosphonomethyl)glycine (PMG, glyphosate) were investigated with infrared (IR) spectroscopy and ab initio frequency calculations. The zwitterionic nature of PMG in solution was confirmed, and intramolecular hydrogen bonding was identified. Successive protonation of the PMG molecule follows the order amine, phosphonate, carboxylate. Intramolecular hydrogen bonding is indicated to exist at all stages of protonation: between both RCO2- and RNH2+ and RPO32- and RNH2+ in HL2- (where L represents the ligand PMG); between RCO2- and RNH2+ in H2L-; predominantly between RPO32- and RNH2+ in H3L. There are strong indications that the zwitterion is intact throughout the pH range investigated. Results from IR and extended X-ray absorption fine structure (EXAFS) spectroscopies provide new evidence for structures of N-(phosphonomethyl)glycinecopper(II) complexes. The structures of 1:1 complexes, CuL- and CuHL, are essentially the same, differing only in protonation of the phosphonate group. Copper(II) lies at the center of a Jahn-Teller distorted octahedron with all three donor groups (amine, carboxylate, phosphonate) of PMG chelating with copper(II) to form two five-membered chelate rings oriented in the equatorial plane. EXAFS indicates that oxygen (most likely a water molecule) is a fourth ligand, which would thus occupy the fourth corner in the equatorial plane of the elongated octahedron. CuL24- most probably forms an isomeric mixture in solution, and there are indications that this mixture is dominated by complexes where two PMG ligands are bound to copper(II) via equatorial and axial positions, with both phosphonate and carboxylate donor groups responsible for chelation at axial positions.

Place, publisher, year, edition, pages
2001. Vol. 40, no 17, 4302-9 p.
URN: urn:nbn:se:umu:diva-8998DOI: doi:10.1021/ic000849gOAI: diva2:148669
Available from: 2008-02-26 Created: 2008-02-26 Last updated: 2011-01-13Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Persson, Per
By organisation

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 41 hits
ReferencesLink to record
Permanent link

Direct link