Issue 5, 1984

The co-ordination chemistry of divalent cobalt, nickel, and copper. Part 10. Characterisation and stability constants of nickel(II) species isolated from a mixed-ligand solution: crystal structure of tris(1,2-diaminoethane)nickel(II) bis(pyridine-2,6-dicarboxylato)nickelate(II) tetrahydrate

Abstract

The complexes, Ni(pydca)(en)·2H2O (1), Ni(pydca)(en)3·2H2O (2), and Ni(pydca)(en)1.5·2H2O (3) were isolated from solutions of nickel(II), pydca, and en (pydca = pyridine-2,6-dicarboxylate, en = 1,2-diaminoethane). Spectral and magnetic data indicate that species (1) and (2) are octahedral and can be formulated as [Ni(pydca)(en)(H2O)]·H2O and [Ni(en)3][pydca]·2H2O, respectively. The structure of (3) was shown by Patterson and Fourier methods to be in accordance with the formula [Ni(en)3][Ni(pydca)2]·4H2O, with a= 9.395(5), b= 10.924(5), c= 15.662(8)Å, α= 70.95(2), β= 101.36(2), γ= 104.91(2)°, Z= 2, triclinic, and space group P[1 with combining macron]. Heating (1) gave a compound with the empirical formula Ni(pydca)(en). Infrared and magnetic data indicate that this species is monomeric and five-co-ordinate. A compound with the same empirical formula, Ni(pydca)(en), was obtained by heating (3), but spectral data and a magnetic moment of 3.40 B.M. for this product suggest the formula [Ni(en)2][Ni(pydca)2], containing [Ni(en)2]2+ with Cs symmetry. A plot of complex-ion concentrations as a function of Ni : en ratio in solution was derived from measured stability constants and was used to explain the stepwise isolation of species (1), (3), and (2).

Article information

Article type
Paper

J. Chem. Soc., Dalton Trans., 1984, 975-980

The co-ordination chemistry of divalent cobalt, nickel, and copper. Part 10. Characterisation and stability constants of nickel(II) species isolated from a mixed-ligand solution: crystal structure of tris(1,2-diaminoethane)nickel(II) bis(pyridine-2,6-dicarboxylato)nickelate(II) tetrahydrate

J. G. H. du Preez, H. E. Rohwer, B. J. van Brecht and M. R. Caira, J. Chem. Soc., Dalton Trans., 1984, 975 DOI: 10.1039/DT9840000975

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