title: Lanthanide chemistry with (bis[[bis(carboxymethyl)amino]methyl]phosphinate: what does an extra phosphinate group do to EDTA?
abstract: H5XT (bis[[bis(carboxymethyl)amino]methyl]phosphinic acid) is an EDTA(4-)-like ligand containing an extra phosphinate group. [Co(II)(XT)]3-, [Co(III)(XT)]2-, and a series of [Ln(XT)]2- complexes have been prepared. The phosphinate group is not coordinated in the Co complexes but is bound in the lanthanide complexes. Solid state and solution behaviors of Ln-XT species are consistent: both monoprotonated and nonprotonated species have been found. Protonation of the metal complex does not lead to dissociation of a carboxylate; rather, the proton distributes around the molecular ion. The pM values of Ln-XT are comparable to those of Ln-EDTA but are higher than those of Ln-TMDTA. The inclusion of a phosphinate eases the selectivity of an EDTA-type ligand for late lanthanides.
authors.affiliation: Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada.
authors.forename: L
authors.initials: L
authors.lastname: Xu
authors.forename: S J
authors.initials: SJ
authors.lastname: Rettig
authors.forename: C
authors.initials: C
authors.lastname: Orvig
mesh_terms: D003287:Contrast Media / Q000737:chemistry; D018360:Crystallography, X-Ray; D015195:Drug Design; D004355:Drug Stability; D004492:Edetic Acid / Q000737:chemistry; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D008024:Ligands; D009942:Organometallic Compounds / Q000737:chemistry; D004369:Pentetic Acid / Q000737:chemistry; D010721:Phosphinic Acids / Q000737:chemistry*
chemical_list: D003287:Contrast Media; D028581:Lanthanoid Series Elements; D008024:Ligands; D009942:Organometallic Compounds; D010721:Phosphinic Acids; C440493:bis((bis(carboxymethyl)amino)methyl)phosphinate; D004369:Pentetic Acid; D004492:Edetic Acid