Microcalorimetric studies. Heats of complexing of transition metal ions with amino-acids

Abstract

Heats of complexing in aqueous solution have been measured using a Beckman 190B microcalorimeter, for the amino acid ligands, glycine, α-alanine, β-alanine, serine and histidine: the values of –ΔH for forming ML₂ complexes were in the order Co(II)<Ni(II)<Cu(II)>Zn(II), the same as for –ΔG values from stability constant data. Discussion is made of some factors influencing ΔH and ΔS of complex formation.