Molecular structure and DFT study of hydrothermally synthesized niobium oxide fluoride

A niobium oxide fluoride compound, [Hphen][NbOF4]·H2O (1) (phen = 1,10-phenanthroline), has been hydrothermally synthesized and structurally characterized. In the [NbOF4]− anion, the Nb5+ moves toward the oxide ligand to form a short NbO bond. Interestingly, the [NbOF4]− anion is aligned such that the oxide ligand on coordinate to adjacent [NbOF4]− anion, resulting in forming [NbOF4]nn− infinite linear chain. In order to better understand our experimental results, some relevant bonding character and electronic properties of [NbOF4]− anion have been analyzed by performing density functional theory (DFT) calculations. We find that the central metal moves toward the single oxide, and a short apical NbO bond is inherent to [NbOF4]− anion, which mainly stems from the overlap between filled oxide p orbitals and vacant cation d orbitals.