Hafnium alkoxides synthesis

Thermolysis of tin and lead alkoxozirconates leads to the formation of metals. The mass-spectral data indicate the presence ofbarium and aluminium derivatives in the gas phase, but no preparative data are accessible for them. The major application of zirconium and hafnium alkoxides lies now in the sol-gel technology of zirconate-titanate and solid solutions Zr02-Y203 (see Section 10.3), Except in the synthesis of oxide materials, the alkoxides of zirconium and hafnium are traditionally used in the polymer chemistry, where they are applied as the components in catalysts [1278, 1269] and as additives to polymers, improving their characteristics [825, 1403] and so on. Already in 1930s Meerwein has proposed the use of zirconium alkoxides for the reduction of aldehydes intoprimary alcohols (Meerwein-Schmidt reaction) [1420],... 

Turevskaya EP, Kozlova NT Turova NY, Belokon AL, Berdyev DV, Kessler VG, et al. The alkoxides of zirconium and hafnium direct, electrochemical synthesis and mass-spectral study. Do M(0R)4 , where M = Zr, Hf, Sn, really exist . Russ Chem Bull 1995 44(4) 734-42. 

Tetrakis(hexafluoroisopropoxides) of titanium, zirconium, and hafnium have been prepared by the reaction of sodium hexafluoroisopropoxide in an excess of hexafluoroisopropyl alcohol with the anhydrous metal chloride, and the spectroscopic properties are reported. The authors note that, in their experience, application to the Group IV transition metals of the previously published method for metal hexafluoroisopropoxide synthesis gives poor yields of material containing metal, fluorinated alkoxides, and co-ordinated ammonia. Dehydration of the hydrated metal chloride with methyl orthoformate and addition of hexafluoroisopropyl alcohol, followed by passage of dry ammonia through the solution, gives satisfactory yields for yttrium, lanthanum, neodymium, and erbium. 

Synthesis ofheterometallic complexes by direct interaction ofhomometallic alkoxides has been reported in many cases also for the rare earth metals, but in this case it is necessary to keep in mind that the commercial Ln(OTr)3 usually contain the oxoalkoxide complex, Ln50(0 Pr)i3 as their major component. The reactivity of the latter toward other alkoxides is comparably low, and prolonged refluxing in toluene or the reaction in a melt is recommended to insure the completeness of transformation (Poncelet, 1989). The only reaction between the two high-valent metal alkoxides, not involving specific mechanisms with formation of oxoalkoxides, is the formation of the aluminium and hafnium isopropoxide (Turevskaya, 1997) ... 

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