Vanadate


Vanadate

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 [Cotton&Wilkinson6th] . 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.Greenwood&Earnshaw]
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(V).

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 [The Elusive Vanadate (V3O9)3−: Isolation, Crystal Structure, and Nonaqueous Solution Behavior, Hamilton E. E., Fanwick P.E., Wilker J.J., J. Am. Chem. Soc., 124 (1), 78 -82, 2002, doi|10.1021/ja010820r]
* V4O124− cyclic with corner shared VO4 tetrahedra [ [Ni(C10H8N2)3] 2 [V4O12] .11H2O G.-Y. Yang, D.-W. Gao, Y. Chen, J.-Q. Xu, Q.-X. Zeng, H.-R. Sun, Z.-W. Pei, Q. Su, Y. Xing, Y.-H. Ling and H.-Q. Jia, Acta Cryst. (1998). C54, 616-618,doi|10.1107/S0108270197018751 ] ]
* V5O143− corner shared VO4 tetrahedra [A new structure type in polyoxoanion chemistry: synthesis and structure of the V5O143− anion, V. W. Day, Walter G. Klemperer, O. M. Yaghi, J. Am. Chem. Soc.; 1989; 111(12); 4518-4519.doi|10.1021/ja00194a068]
* V10O286− "decavanadate", edge and corner shared VO6 octahedra
* V12O324−
* V13O343− fused VO6 octahedra [Tridecavanadate, [V13O34] 3−, a new high-potential isopolyvanadate, Hou D., Hagen K.D., Hill C.L., J. Am. Chem. Soc.; 1992; 114(14) 5864 - 5866; doi|10.1021/ja00040a061]
* V18O4212− [Polyoxovanadates: High-Nuclearity Spin Clusters with Interesting Host-Guest Systems and Different Electron Populations. Synthesis, Spin Organization, Magnetochemistry, and Spectroscopic Studies , Müller A., Sessoli R., Krickemeyer E., Bögge H., Meyer J., Gatteschi D., Pardi L., Westphal J., Hovemeier K., Rohlfing R., Döring J, Hellweg F., Beugholt C., Schmidtmann M., Inorg. Chem., 36 (23), 5239 -5250, 1997. doi|10.1021/ic9703641]

Some examples of polymeric “infinite” ions are:
* [VO3] nn− in e.g. NaVO3, sodium metavanadate
* [V3O8] nn− in CaV6O16 [On a new calcium vanadate: synthesis, structure and Li insertion behaviour, Jouanneau, S.; Verbaere, A.; Guyomard, D., Journal of Solid State Chemistry, 172, 1, 116-122, doi|10.1016/S0022-4596(02)00164-0]

In these ions vanadium exhibits tetrahedral, square pyramidal and octahedral coordination. In this respect V shows similarities to W and Mo, chromium however has a more limited range of ions .

Aqueous solutions

Vanadium pentoxide when dissolved in strong base, e.g. NaOH, a colourless solution containing the VO43- ion is produced. On acidification the colour gradually deepens through orange to red at around pH 7, before brown hydrated V2O5 precipitates around pH 2, redissolving to form a light yellow solution containing the vanadyl, VO2+ ion.
Between pH 13 and pH 2 a complex set of pH and concentration dependent equilibria are present involving protonation and condensation of vanadate species to produce polyoxovanadate ions of different types:

* pH 9- pH 12; HVO42−, V2O74−
* pH 4- pH 9; H2VO4, V4O124−, HV10O285−
*pH 2 - pH 4; H3VO4, H2V10O284−

References


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Vanadate — Van a*date, n. [Cf. F. vanadate.] (Chem.) A salt of vanadic acid. [Formerly also {vanadiate}.] [1913 Webster] …   The Collaborative International Dictionary of English

  • vanadate — [vanadat] n. m. ÉTYM. V. 1830; de vanad(ium), et ate. ❖ ♦ Chim. Sel simple ou complexe dérivé d un acide vanadique. || « Du vanadate de plomb qui constitue le principal minerai de vanadium » (Rev. gén. des sc., 30 juin 1904, no 12, p. 616) …   Encyclopédie Universelle

  • Vanadate —   [v ], Singular Vanadat das, (e)s, Vanadiumverbindungen …   Universal-Lexikon

  • vanadate — [van′ə dāt΄] n. a salt or ester of vanadic acid …   English World dictionary

  • Vanadate — Struktur der Orthovanadiumsäure H3VO4 Vanadate sind die Salze der in freier Form nicht existenten Vanadium Säuren HxVyOz. Die Vanadate selbst sind in wässriger Lösung stabil, wobei die auftretenden Formen vom pH Wert der Lösung abhängen. Einige… …   Deutsch Wikipedia

  • Vanadate — Ion vanadate En chimie, un vanadate est un composé comportant l oxoanion du vanadium en général à son degré d oxydation le plus élevé, +5. Le plus simple élément de cette famille est l ion tétraédrique vanadate ou orthovanadate, l anion VO43−,… …   Wikipédia en Français

  • vanadate — (= VO43 ) Powerful inhibitor of many, but not all enzymes that cleave the terminal phosphate bond of ATP. The vanadate ion is believed to act as an analogue of the transition state of the cleavage reaction. Dynein is very sensitive to inhibition… …   Dictionary of molecular biology

  • vanadate — noun Etymology: New Latin vanadium + English 1 ate Date: 1835 a salt derived from vanadium pentoxide and containing pentavalent vanadium …   New Collegiate Dictionary

  • vanadate — /van euh dayt /, n. Chem. a salt or ester of a vanadic acid. Also, vanadiate /veuh nay dee ayt /. [1830 40; VANAD(IC ACID) + ATE2] * * * …   Universalium

  • vanadate — noun a) any salt of vanadic acid b) any of the corresponding anions, VO, VO, or VO …   Wiktionary


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.