Heterometallic alkoxide derivatives, synthesis

As has been mentioned above, the special interest in these derivatives is connected with their application in the synthesis of the complex oxide materials (see Chapter 10 for details). The heterometallic alkoxides have been discussed in a number of reviews, the most complete of those (at different moments in time) being the corresponding chapter in the book by Bradley et al. [223] and articles of Mehrotra [1138] and also of Caulton and Hubert-Pfalz-graf [306],... 

A new dimension has been opened during the last decade in the field of heterometal coordination chemistry because of the synthesis of a variety of thermally stable ter and higher heterometallic alkoxides. This area is expected to receive increasing attention because of the first X-ray structural elucidation done in 1996 (39a) of a termetallic isopropoxide of Ba, Zr, and Cd. This derivative also revealed an even more fascinating behavior of the shifting of the alkoxo-metallate ligands to suit the nature of the three metals involved in the species. 

Synthesis of Higher Heterometallic Alkoxides and Allied Derivatives... 

In spite of considerable initial scepticism, the synthesis of an increasing number of well-characterized heterometallic alkoxides is now well established and attempts are being directed towards the synthesis of single-source precursors for preparation of mixed metal-oxide ceramic materials by the sol-gel or MOCVD processes. " " Before proceeding to a brief account of some novel types of heterometal glycolate and aminoalkoxide derivatives, it is appropriate to mention four review articles" summarizing the state of knowledge about the conventional heterometallic alkoxide systems at the end of the twentieth century. 

The chemical properties of heterometallic alkoxides are in general similar to their homometal counterparts (i) hydrolysis, (ii) alcoholysis, (iii) trans-esterification reactions, (iv) reactivity with carboxylic acids and enolic forms of chelating ligands such as /3-diketones/j6-ketoesters. The hydrolytic reactions are now widely employed for the preparation of homogeneous mixed metal-oxide ceramic materials and the rest have found wide applications for the synthesis of a variety of novel metallo-organic derivatives (sometimes unique), which are not often available through any other synthetic route. ... 

The synthesis of volatile and soluble (in organic solvents) covalent d83-i85 jjona-alkoxodizirconates of alkali metals such as KZr2(OR)9 (R = Et, Pr ), by Bartley and Wardlaw in 1958 initiated an entirely new dimension in the chemistry of heterometallic alkoxides. Historically, a nona-alkoxostannate derivative, NaSn2(OEt>9 had been described by Bradley et in 1957 as an intermediate during their efforts to synthesize tin tetra-alkoxides by the reactions of SnCLj with NaOEt. 

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