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In chemistry, a vanadate is a compound containing an oxoanion of vanadium generally in its highest oxidation state of +5. The simplest vanadate ion is the tetrahedral, orthovanadate, VO43− anion, which is present in e.g. sodium orthovanadate and in solutions of V2O5 in strong base (pH > 13 ). Conventionally this ion is represented with a single double bond, however this is a resonance form as the ion is a regular tetrahedron with four equivalent oxygen atoms. Additionally a range of polyoxovanadate ions exist which include discrete ions and "infinite" polymeric ions. There are also vanadates, such as rhodium vanadate, RhVO4, which has a statistical rutile structure where the Rh3+ and V5+ ions randomly occupy the Ti4+ positions in the rutile lattice,〔Wells A.F. (1984) ''Structural Inorganic Chemistry'' 5th edition Oxford Science Publications ISBN 0-19-855370-6〕 that do not contain a lattice of cations and balancing vanadate anions but are mixed oxides. In chemical nomenclature when vanadate forms part of the name, it indicates that the compound contains an anion with a central vanadium atom, e.g. ammonium hexafluorovanadate is a common name for the compound (NH4)3VF6 with the IUPAC name of ammonium hexafluoridovanadate(III). ==Examples of vanadate ions== Some examples of discrete ions are *VO43− "orthovanadate", tetrahedral.〔 *V2O74− "pyrovanadate", corner shared VO4 tetrahedra similar to dichromate ion〔 *V3O93− cyclic with corner shared VO4 tetrahedra *V4O124− cyclic with corner shared VO4 tetrahedra *V5O143− corner shared VO4 tetrahedra *V10O286− "decavanadate", edge and corner shared VO6 octahedra〔 *V12O324−〔 *V13O343− fused VO6 octahedra *V18O4212− Some examples of polymeric “infinite” ions are *()''n''''n''− in e.g. NaVO3, sodium metavanadate〔 *()''n''''n''− in CaV6O16 In these ions vanadium exhibits tetrahedral, square pyramidal and octahedral coordination. In this respect vanadium shows similarities to tungstate and molybdate, chromium however has a more limited range of ions. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Vanadate」の詳細全文を読む スポンサード リンク
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