Abstract
The stability constants of the complexes of one oligophosphonic acid (ethane-1,1,2-triphosphonic acid 1), five phosphonocarboxylic acids (ethane-1,2-diphospho-no-1-carboxylic acid 2, propane-1,1-diphosphono-2,3-dicarboxylic acid 3, ethane-1,2-diphosphono-1,2-dicarboxylic acid 4, ethane-1-phosphono-1,2-dicarboxylic acid 5, and propane-1-phosphono-1,2,3-tricarboxylic acid 6), and ethane-1,1,2-tricarboxylic acid 7 with Cu2 +, Ni2 +, Zn2 +, Cd2 + and Ca2 + were determined by pH-metric titrations. The six ligands of type HNL (N = 4 – 6) form mononuclear MLHn (n = 0, 1, …, N–1) complexes with chelate structure. The calcium complexes seem to be less stable than the transition metal complexes.
Acknowledgments
Currently at KFKI Research Institute for Particle and Nuclear Physics, Budapest, Hungary.
Cs. Bogdán is indebted to Prof. Ferenc Gaizer (Prof. Emeritus of the Institute of Chemistry, Eötvös Loránd University, Budapest, Hungary), whose help, hints and stimulating suggestions contributed to the current work.
Notes
a –P and –C denote –PO3H2 and –COOH groups, respectively;
b number of measured points per titration curve.