Di­aqua­bis­(nicotinamide-κN¹)bis­(thio­cyanato-κN)nickel(II)

In the title complex, [Ni(NCS)₂(C₆H₆N₂O)₂(H₂O)₂], the Ni^II ion is located on an inversion center and is coordinated in a distorted octa­hedral environment by two N atoms from two nicotinamide ligands and two water mol­ecules in the equatorial plane, and two N atoms from two thio­cyanate anions in the axial positions, all acting as monodentate ligands. In the crystal, weak N—H...S hydrogen bonds between the amino groups and the thio­cyanate anions form an R₄²(8) motif. The complex mol­ecules are linked by O—H...O, O—H...S, and N—H...S hydrogen bonds into a three-dimensional supra­molecular structure. Weak π–π inter­actions between the pyridine rings is also found [centroid–centroid distance = 3.8578 (14) Å].

(E)-2-{[4-(Di­methyl­amino)­benzyl­idene]amino}-5-nitro­phenol

The title Schiff base compound, C₁₅H₁₅N₃O₃, crystallizes with two mol­ecules (A and B) in the asymmetric unit. Each mol­ecule adopts an E conformation around the C= N imine bond. The two mol­ecules have minor differences in their conformations. In mol­ecule A, the dihedral angle between the nitro group and its benzene ring is 2.1 (2)° and that between the two benzene rings is 0.88 (7)°, while the corresponding angles for mol­ecule B are 5.7 (1) and 2.45 (6)°, respectively. In each mol­ecule, there is an intra­molecular O—H...N hydrogen bond. In the crystal, inversion-related mol­ecules are linked via O—H...O hydrogen bonds forming A–A and B–B dimers. These dimers are linked via C—H...O hydrogen bonds involving the nitro O atoms, forming A–A–A and B–B–B slabs that lie parallel to one another and to (010).