Tantalum ethoxides

Reactions with alcohols in the presence of an amine forms dinuclear alkox-ides. Thus, with ethanol in the presence of diethylamine, the dinuclear tantalum ethoxide, Ta2(OC2H5)io, is obtained. 

The metal salts of alcohols are called alkoxides, M(OR), where M is a metal and R is an alkyl group. Typical examples in the synthesis of ferroelectric thin films include titanium isopropoxide [Ti(OPr )4 where Pr represents isopropyl], tantalum ethoxide [Ta(OEt)5 where Et represents ethyl], and zirconium butoxide butanol [Zr(OBu )4 n-BuOH where Bu represents -butyl], an alkoxide/alcohol compound. The structure of this compound, shown in Figure 27.3a, illustrates its dimeric nature, that is, the fact that each molecule contains two metal centers. 

Kukli K., Ritala M., Leskelae M. Atomic layer deposition and chemical vapor deposition of tantalum oxide by successive and simultaneous pulsing of tantalum ethoxide and tantalum chloride. Chem. Mater. 2000 12 1914-1920... 

Scheme 27.4 Reactions of tantalum ethoxide, Ta(OC2H5)5, with 1,3-propanediol, 0H-(CH2)3-0H. An air-stable solution is synthesized with appropriate rheological properties for use as a CSD precursor.

The direct electrochemical synthesis of metal alkoxides by the anodic dissolution of metals into alcohols containing conducting electrolytes was initially demonstrated by Szilard in 1906 for the methoxides of copper and lead.19 More recently the method has received some attention particularly in the patent literature.29-25 The preparation of the ethoxides of silicon, titanium, germanium, zirconium and tantalum by electrolysis of ethanolic solutions of NH Cl has been patented, although the production of the ethoxides was found to cease after several hours.24,25... 

Metal alkoxide Tantalum(V) ethoxide, TafOCfLCfDs Solid... 

The pentavalent niobium and tantalum alkoxides are reasonably volatile and can be distilled unchanged in the pressure range 0.05-10mm, e.g. pentamethoxides of niobium" and tantalum" have been distilled at 153°C/0.1 or 200°C/5.5 and 130°C/0.2 or 189°C/10.0 mm pressures, respectively. The data in Table 2.12 indicate that the boiling points are dependent on chain length furthermore, the methoxides and ethoxides of tantalum are more volatile than the niobium analogues whereas for higher n-alkoxides, the reverse is... 

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