Ester elimination: A general solvent dependent non-hydrolytic route to metal and mixed-metal oxides

Molecular routes to metal oxides has become an area of intense scientific interest due to the technological relevance of these materials. Molecular routes are proving important as a result of the possibility to control the physical and chemical properties of the final materials. We have chosen to study non-hydrolytic methods, namely ester elimination reactions between two prototypical molecular precursors metal alkoxides, M(OR)(n), and metal carboxylates, M(O(2)CR)(n), to synthesize metal oxides: M(OR)(n) + M'(O(2)CR')(n) --> MM'(O)(x)(OR)(n-x)(O(2)CR')(n-x) + xRO(2)CR' MM'(O)(x)(OR)(n-x)(O(2)CR')(n-x) --> MM'(O)(n) + n - xRO(2)CR This method allows for the synthesis of pure metal oxides by complete elimination of the organic supporting ligands with concomitant formation of M-O-M' bridges. Furthermore, incomplete ester elimination can lead to isolation of molecular clusters as intermediates which can also be used as building blocks for the formation of metal oxides with controlled microstructure. Here we report a series of reactions between Sn and Si alkoxides and carboxylates designed to gain further insight into the factors governing ester elimination reactions. By choosing compounds with varying coordination environments and steric accessibility we have devised a set of criteria which should allow for successful ester elimination between metal alkoxide and carboxylate compounds. Furthermore we have also shown the ability of ester elimination derived molecular clusters with specific microstructure to be used in the synthesis of bulk materials retaining the structural attributes of the precursor cluster.