Critical evaluation of stability constants of phosphonic acids (IUPAC Technical Report)

Abstract

Available experimental data on stability constants of proton and metal complexes for 10 phosphonic acids [methylphosphonic acid, 1-hydroxyethane-1,1-diylbisphosphonic acid, dichloromethylenebisphosphonic acid, amino-methanephosphonic acid, N-(phosphonomethyl)glycine, imino-N,N-bis(methylenephosphonic acid), N-methylamino-N,N-bis(methylenephosphonic acid), nitrilotris(methylenephosphonic acid), 1,2-diaminoethane-N,N,N´,N´-tetrakis-(methylenephosphonic acid), and diethylenetriamine-N,N,N´,N´´,N´´-pentakis-(methylenephosphonic acid)], published in 1950­1997, have been critically evaluated. For the latter phosphonate, all the data are rejected, as well as protonation constants [HL]/[H][L] for three other ligands. Higher-quality data are selected and presented as "Recommended" and "Provisional".