Studies on the metalamide bond. XII. The crystal structure of [N,N′-bis(2′-pyridinecarboxamido)-1,2-ethane]nickel(II) monohydrate

[N,N′-Bis(2′-pyridinecarboxamido)-1,2-ethane]nickel(II) monohydrate, C₁₄H₁₄N₄O₃Ni, is monoclinic, space group I2/a, with a = 7.241(3), b = 17.141(6), c = 11.132(3) Å, β = 102.2(1)°, Z = 4. The structure was refined to R = 0.071 for 949 photographic reflexions by least-squares calculations. The molecules have space group imposed C2(2) symmetry. The nickel atom is four coordinate with the ligand acting, as a planar N₄-tetradentae [NiN(amide) 1.839(6), NiN(pyridine) 1.952(6) Å, N(amide)NiN(amide) 82.9(3)°, N(pyridine)NiN(pyridine) 108.4(3)°]. The amide nitrogen atom is almost trigonally planar, and that the ligand can adopt a nearly planar arrangement about the nickel atom is due to the flexible ethylene link. The chelate molecules stack with their molecular planes parallel to (101. The water molecule hydrogen bonds the carboxyl oxygen atoms of two chelate molecules which are related by the two-fold axis contained by it.