Crystal structure of hexaaquanickel(II) bis{2-[(5,6-dihydroxy-3-sulfonatoquinolin-1-ium-7-yl)oxy]acetate} dihydrate

Abstract

The asymmetric unit of the title compound, [Ni(H2O)6](C11H8NO8S)2·2H2O, features a half-hexaaquanickel(II) complex cation with the NiIIion on an inversion center, one deprotonated 5,6-dihydroxy-3-sulfoquinolin-7-yloxyacetic acid (QOH) molecule appearing in its zwitterionic form and one lattice water molecule. The sulfonate group is disordered over two positions with occupancy factors of 0.655 (5) and 0.345 (5). The hexaaquanickel(II) cation interacts through hydrogen bonding with eightQOHmolecules and two water molecules. The six-membered rings of quinoline show π–π stacking [centroid-to-centroid distances of 3.679 (2) Å and 3.714 (2) Å].