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Tantalum(V) ethoxide

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Tantalum(V) ethoxide
Names
IUPAC name
Tantalum(5+) pentaethanolate
Other names
  • Tantalum ethylate
  • Tantalum(V) ethylate
  • Pentaethyl tantalate
  • Tantalum pentaethoxide
  • Pentaethoxytantalum(V)
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.025.464 Edit this at Wikidata
EC Number
  • 228-010-2
  • [Ta+5].[O-]CC.[O-]CC.[O-]CC.[O-]CC.[O-]CC
Properties
C10H25O5Ta
Molar mass 406.25 g mol-1
Appearance Colorless liquid
Density 1.566 g/cm3 (at 25°C)
Melting point 21 °C (70 °F; 294 K)
Boiling point 145 °C (at 0.0133 kPa)
1.488 [1]
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
2
1
2
W
Flash point 87 °F
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Tantalum(V) ethoxide is an metalorganic compound with formula Ta2(OC2H5)10. It is a colorless solid that dissolves in some organic solvents but hydrolyzes readily.[3] It is mainly used for the sol-gel processing of materials containing niobium oxides.[4]

Structure

Metal alkoxides rarely adopt monomeric structures and tantalum ethoxide is no exception. Early studies established that tantalum alkoxides are aggregate in solution as dimers.[5] Subsequent crystallographic analysis established that the methoxide and isopropoxides of niobium adopt bioctahedral structures.[6]

Preparation and reactions

This compound is prepared by salt metathesis from tantalum pentachloride (Et = C2H5):

10 NaOEt + Ta2Cl10 → Ta2(OC2H5)10 + 10 NaCl

The same compound can be prepared electrochemically.[4] The two half reactions are:

cathode: EtOH + e- → EtO- + H2
anode: Ta → "Ta5+" + 5 e-

The most important reaction of tantalum alkoxides is their hydrolysis to produce films and gels of tantalum oxides. Although these reactions are complex, they can be described by this simplified equation:

Ta2(OC2H5)10 + 5 H2O → Ta2O5 + 10 HOEt

In a related reaction, treatment with carboxylic acids gives oxo-alkoxide-carboxylates, e.g., Ta4O4(OR)8(OOCCH3)4.[4]

References

  1. ^ "Tantalum Ethoxide and Niobium Ethoxide". Retrieved 19 October 2012. {{cite web}}: Unknown parameter |publishers= ignored (|publisher= suggested) (help)
  2. ^ "Tantalum (V) ethoxide 99.98% trace metals basis". Sigma Aldrich. Retrieved 18 October 2012.
  3. ^ Lide, David R., ed. (2006). CRC Handbook of Chemistry and Physics (87th ed.). Boca Raton, FL: CRC Press. ISBN 0-8493-0487-3.
  4. ^ a b c U. Schubert "Sol–Gel Processing of Metal Compounds" Comprehensive Coordination Chemistry II 2003, Pages 629–656 Volume 7. doi:10.1016/B0-08-043748-6/06213-7
  5. ^ D. C. Bradley and C. E. Holloway, "Nuclear magnetic resonance studies on niobium and tantalum penta-alkoxides" J. Chem. Soc. A, 1968, 0, 219-223. doi:10.1039/J19680000219
  6. ^ Ram C. Mehrotra, Anirudh Singh "Recent Trends in Metal Alkoxide Chemistry" Progress in Inorganic Chemistry, 1997, Volume 46, p. 239ff. doi:10.1002/9780470166475.ch4
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