Density Functional Theory Study of TinO2n-m Clusters (n=1-4, m=0,1)

Using density functional theory, the equilibrium geometries of TinO2n and TinO2n-1 clusters (n=1-4) have been obtained. It suggests that the structures of these two corresponding clusters are changed slightly, except for the number of terminal oxygen atoms. The electronic properties have also been investigated. The bond between Ti and terminal oxygen atom is found to be more covalent than other Ti-O bonds. It also indicates that by deleting one terminal oxygen atom, HOMO is mainly derived from titanium atoms with least coordination, but not from singly-coordination oxygen atoms as that in the stoichiometric clusters. Highest energy levels of least-coordination Ti atoms shift highly and they become more reactive. In addition, HOMO-LUMO energy gaps and binding energies were observed. The calculated results show that the energy gaps decrease quickly, except for Ti4O7 clusters and all the binding energies are relatively large.

Fluorreiche Oxofluorovanadate(V): Die Kristallstruktur von [enH2][VOF5]. / Fluorine-Rich Oxofluorovanadates(V): Crystal Structure of [enH2][VOF5]

The crystal structure of triclinic [enH2][VOF5], prepared in aqueous solution, has been determined from X-ray diffractometer data (R = 0.076 for 527 reflections). The structure contains monomeric [VOF5]2--ions. The bond distances are 1.54(1) Å (terminal oxygen), 1.80(1) (average for the cis-fluorine atoms) and 2.10(1) Å for the fluorine atom in transposition to the terminal oxygen atom. This fluorine atom is involved in strong hydrogen bonds originating from the [NH3CH2CH2NH3]2+ cation with cisoid conformation. Earlier results about the existence of K2VOF5 could not be confirmed

Oxofluoro-oxalato-vanadate des vierwertigen Vanadins: Schwingungsspektrum und Struktur von Na3[VOF(C2O4)2] • 6 H2O.

The Na and NH4 salts of the [VOF(C2O4)2]3--ion have been prepared. The crystal structure of the former has been determined from X-ray diffractometer data. The crystals are triclinic, space group P with Z = 2. The structure was solved by `direct methods' and refined to R 0.050 for 1749 reflections. In the anion, vanadium(IV) is octahedrally coordinated by a terminal oxygen atom, a fluorine atom in cis-position to the former, and two bidentate oxalate ligands. The terminal V—O-bond exhibits a strong ‘trans’ effect.