Abstract
In the title compound, [Hf(C(9)H(6)NO)]·C(3)H(7)NO·H(2)O, the hafnium(IV) atom is coordinated by four 8-quinolinolate (Ox) ligands, forming a slightly distorted square-anti-prismatic coordination polyhedron. The crystal packing is controlled by O-H⋯O and C-H⋯O hydrogen-bonding inter-actions and π-π inter-actions between quinoline ligands of neighbouring mol-ecules. The inter-planar distances vary between 3.150 (1) and 3.251 (2) Å, while centroid-centroid distances vary from 3.589 (1) to 4.1531 (1) Å.