catena-Poly[bis(μ-2,2′-bipyridin-6-olato)-κ3N,N′:O;O:N,N′-dicopper(I,II) [[tetrafluoridoniobium(V)]-μ-oxido]]

Abstract

A novel copper–niobium oxyfluoride, {[Cu2(C10H7N2O)2][NbOF4]}n, has been synthesized by a hydrothermal method and characterized by elemental analysis, EDS, IR, XPS and single-crystal X-ray diffraction. The structural unit consists of oneC2-symmetric [NbOF4]−anion and one centrosymmetric coordinated [Cu2(obpy)2]+cation (obpy is 2,2′-bipyridin-6-olate). In the [NbOF4]−anion, each NbVmetal centre is five-coordinated by four F atoms and one O atom in the first coordination shell, forming a square-pyramidal coordination geometry. These square pyramids are then further connected to each othervia transO atoms [Nb—O = 2.187 (3) Å], forming an infinite linear {[NbOF4]−}npolyanion. In the coordinated [Cu2(obpy)2]+cation, the oxidation state of each Cu site is disordered, which is confirmed by the XPS results. The disordered Cu sites are coordinated by two N atoms and one O atom from two different obpy ligands. The [NbOF4]−and [Cu2(obpy)2]+units are assembledviaweak C—H...F hydrogen bonds, resulting in the formation of a three-dimensional supramolecular structure. π–π stacking interactions between the pyridine rings [centroid–centroid distance = 3.610 (2) Å] may further stabilize the crystal structure.