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Stabilization of a hydrated ketone by metal complexation. The crystal and molecular structures of bis-2,2′,N,N′-bipyridyl ketone-hydrate nickel(II) sulfate, copper(II) chloride and copper(II) nitrate

1986; Elsevier BV; Volume: 111; Issue: 1 Linguagem: Inglês

10.1016/s0020-1693(00)82219-7

1873-3255

Wang Sue-Lein, James W. Richardson, Shelley J. Briggs, Robert A. Jacobson, William P. Jensen,

Magnetism in coordination complexes

The crystal structure of the complexes (I)Ni[C11N8N2(OH)2]2SO4, (II) Cu[C11H8N2(OH)2]2Cl2· 4H2O and (III) Cu[C11H8N2(OH)2]2(NO3)2·2H2O have been determined by three-dimensional X-ray analysis methods. Crystal data are: (I), monoclinic, space group C2/c, Z = 4, a = 19.666(4), b = 7.994(2), c = 16.045(6) /rA, /gb = 111.231(9)°, (II), monoclinic, space group C2/c, Z = 4, a = 14.504(4), b = 12.333(8), c = 14.630(3) Å, /gb = 90.92°; and (IIl), monoclinic, space group P21/n, Z = 2, a = 7.601(5), b = 11.977(4), c = 14.463(6) Å, β = 93.10(8)°. These structural investigations clearly demonstrate that in each case hydration occurs across the ketone double bond in the ligand and that the resulting hydroxyl group coordinates to the metal. Two di-2-pyridyl ketone ligands are thus bonded to the metal atom in a tridentate fashion. In the nickel complex (I), all six coordination interactions appear to have approximately the same strength. However, in the copper complexes (II) and (III), the pyridyl nitrogens are strongly coordinating to the metal in the equatorial plane, while the hydroxyl groups are more weakly coordinating in the axial direction. The metal to ligand bond distances are: (I) dNi−O = 2.098(4), dNiN = 2.062(4), 2.087(4) Å, (II) dCuO = 2.465(5), dCuN = 1.994(5), 2.006(5) Å, (III) dCuO = 2.464(5), dCuN = 1.990(5), 2.036(5) Å. The neutral diol that results from hydrolysis of di-2-pyridyl ketone is stabilized by coordination to the metal and such coordination is little affected by changes in the metal, the anion or the extent of hydration.