Niobium ethoxide

Description

Niobium Ethoxide (Nb(OEt)5)

Niobium ethoxide is the niobium(V) alkoxide derived from ethanol, commonly used as a precursor for niobium oxide materials and as a catalyst/support precursor in sol–gel and related syntheses.

Chemical identity and structure

• Formula: Nb(OEt)5 (also written Nb(OC2H5)5)
• Oxidation state of Nb: +5
• Typical structure: In solid form, niobium alkoxides often form polymeric networks; in solution they can coordinate solvent molecules. The Nb–O bonds link to five ethoxide ligands.

Synthesis and preparation

Two common preparation approaches:

1. Salt metathesis (alkoxide exchange):

   • NbCl5 + 5 NaOEt → Nb(OEt)5 + 5 NaCl
   • This method uses sodium ethoxide as the ethoxide source to form the niobium ethoxide.

2. Transesterification or ester exchange (from other Nb–OR reagents):

   • Nb(OiPr)5 + 5 EtOH → Nb(OEt)5 + 5 iPrOH
   • This method swaps ester groups with ethanol when starting from another niobium alkoxide.

• Both routes require strictly dry, inert conditions because Nb(OEt)5 is moisture sensitive and hydrolyzes readily in air.

Physical properties (typical expectations)

• Appearance: Often a colorless to pale yellow solid or viscous liquid, depending on prevailing conditions and impurities.
• Stability: Reactive toward water and oxygen; handled under dry, inert atmosphere.
• Volatility: Not highly volatile; typically stored in sealed containers.

Reactivity and hydrolysis

• Moisture sensitivity: Reacts with water to form niobium oxide/hydroxide species and ethanol.
• Hydrolysis products: Under hydrolysis, Nb(OEt)5 tends to form Nb2O5-based networks (sol–gel derived) with release of ethanol.
• Coordination behavior: In solution, it can coordinate with solvent molecules and may form oligomeric species.

Applications and uses

• Sol–gel chemistry: Primary use as a Nb source to prepare Nb2O5-based materials, ceramics, or thin films.
• Catalysis: Used as a precursor for acidic Nb-containing catalysts and as a component in mixed oxide materials.
• Materials science: Helps in fabricating dielectric, optical, and catalytic Nb-containing materials via controlled hydrolysis and condensation.

Handling and safety

• Storage: Keep under strictly dry, inert atmosphere; store in a tightly closed container, away from moisture.
• Safety concerns: Corrosive and irritant; handle with appropriate PPE (gloves, eye protection, lab coat) and ensure good ventilation.
• Disposal: Follow local regulations for inorganic metal alkoxide waste; avoid releasing to the environment or moisture.