Novel complexes of [Co.sup.2+], [Ni.sup.2+], and [Cu.sup.2+] with N-aminosuccinic acid: synthesis, thermal, spectroscopic, and coordination aspects

Complexes of [Co.sup.2+], [Ni.sup.2+], and [Cu.sup.2+] with N-(phosphonomethyl)aminosuccinic acid ([H.sub.4]PMAS) of general formula [Na.sub.2]MPMAS x n[H.sub.2]O [M=Co(II), Ni(II), Cu(II), n--number of water molecules] were synthesized. Based on interpretation of diffusion reflectance spectroscopy, structure of all complexes is based on distorted octahedral. Analysis of IR spectra of Co(II), Ni(II), and Cu(II) N-(phosphonomethyl)aminosuccinates demonstrated that metal ions are coordinated to the ligand through nitrogen atom of the imino group, oxygen atoms of the α-and β-carboxyl groups as well as oxygen atom of the phosphonic group of the [H.sub.4]PMAS. We demonstrated that thermal stability of complexes increases in sequence Cu(II) < Ni(II) < Co(II), obviously as a result of change over from the dimeric to polymeric character of the initial complex. Complete decomposition of ligand occurs at these temperatures and is accompanied by release of [H.sub.2]O, C[O.sub.2], and N[O.sub.2]. The final products of thermal decomposition of the complexes are mixtures of oxides and phosphates of respective metals.