Tetraaquabis(p-nitrosalicylato) Complexes of Zinc(II) and Cobalt(II)

In the title compounds having the general formula [M(C₇H₄NO₅)₂(H₂O)₄], where M = Zn^II, Co^II and Ni^II, the coordination polyhedron around the metal atom is a slightly distorted octahedron involving one carboxy O atom from each p-nitrosalicylato ligand and the O atoms of the four water molecules. The mean M-O_water and the M-O_carboxyl distances are 2.126 (1) and 2.047 (1) Å, respectively, for the Zinc complex, and 2.118 (1) and 2.052 (1) Å, respectively, for the cobalt complex. Centrosymmetric monomers are cross-linked via intermolecular hydrogen bonds.

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