Collect. Czech. Chem. Commun. 1980, 45, 1477-1484

Nickel(II) complexes of phosphinetriacetic acid

Jana Podlahov√°

Department of Inorganic Chemistry, Charles University, 128 40 Prague 2


The interaction of phosphinetriacetic acid (H3X) with nickel(II) was examined under various conditions using potentiometric study of solution equilibria, preparation of solid complexes, spectra (electronic and IR) and other methods. In aqueous solutions, the ligand acts as tridentate through the phosphorus atom and two carboxylic groups to form hexacoordinate complexes, NiX-, NiHX and NiX4-2. At 0.8 X/Ni 1.7 and pH 6-8, these complexes are slowly transformed to Ni3X2, an insoluble polymeric compound. In non-aqueous solvents, trans-square planar complexes Ni(hal)2(H3X2) (hal = Cl, Br, I) are formed, which contain the ligand coordinated through the phosphorus atom alone. While the solid iodocomplex is also planar, the solid chlorocomplex is hexacoordinated with carbonyl oxygens in axial sites. Both isomeric forms of the bromocomplex were isolated in the solid state.