cyclo-Tetra-μ-oxido-tetra-kis-[(acetyl-acetonato-κO,O')bis-(ethano-lato-κO)niobium(V)].

The asymmetric unit of the title tetra-nuclear niobium(V) compound, [Nb(4)(C(2)H(5)O)(8)(C(5)H(7)O(2))(4)O(4)], contains two Nb(V) atoms, two bridging O atoms, two acetyl-acetonate and four ethano-late ligands. Each Nb(V) atom is six-coordinated by the bridging O atoms, two ethano-late and one chelating acetyl-acetonate ligands. The Nb-O distances vary between 1.817 (2) and 2.201 (2) Å and the O-Nb-O angles vary between 78.88 (8) and 102.78 (9)°, illustrating the significant distortion from ideal ocahedral geometry. The rest of the tetra-nuclear unit is generated through an inversion centre. The C atoms of two of the ethano-late mol-ecules are disordered over two sites [occupancy ratio 0.601 (12):0.399 (12)].