Synthesis and Crystal Structure of the Novel Three-dimensional Vanadium Coordination Compound Potassium Oxo-bis(hydroxylamido)malonatovanadate(V)

In the crystal structure of the title complex, K2[(VO)2(NH2O)4(C3H2O4)2] · 3H2O, the V(V) centre is bound to a chelating malonate ligand, two bidentate hydroxylamido ligands and one oxo ligand, defining a pentagonal bipyramidal coordination (VO5N2). The potassium cations are found to adopt two types of coordination geometry with the malonate ligand, the bidentate hydroxylamido ligand and water molecules: the first one is hepta-coordinate in an irregular K(1)O7 polyhedron, and the second one is octa-coordinate in an irregular K(2)O8 polyhedron. The K(1)O7/K(2)O8 and VO5N2 polyhedra are closely linked by sharing faces to form K-V dinuclear units KVO9N2 and KVO10N2, respectively. The two close-packed units, KVO9N2 and KVO10N2, are connected by sharing edges to generate a tetrameric unit K2V2O17N4. Each of these units is joined to four neighbouring units by sharing corners, providing further propagation into a two-dimensional layer. Adjacent layers are connected via the carboxylic oxygen atoms of the malonate units to give a three-dimensional framework in the crystals.