Hexa-tantalates

Tantalates are numerous, and form important ores of tantalum. Of these the most important is tantalite, which is ferrous meta tantalate, Fe(Ta08)2. These salts are all insoluble in water. Both ortho- and pyro-tantalates are known. In addition some important salts are derivatives of the hypothetical hexa-tantalic acid, H8Ta 0,j, whose sodium and potassium salts are soluble in water. 

In addition to the chemistry of heterometallic derivatives of alkoxometallate(iv), and tetraalkoxoaluminate ligands, the properties of hexa alkoxoniobates and -tantalates of various metals have also been extensively studied. An account of these different alkoxometallates is presented in Section 3.3, after presentation of their general properties in Section 3.2. 

Properties of Tetra-alkoxoaluminate and Hexa alkoxoniobate (-tantalate) Derivatives... 

Compared to the tetra-alkoxoaluminates, the corresponding hexa-alkoxoniobate and -tantalate derivatives of most of the metals are less stable. Of these two, the niobate products tend to disproportionate more readily this is reflected in the conductivity curves obtained in the titrations of niobium and tantalum pentaisopropoxide with alkali (Na, K) isopropoxides in isopropyl alcohol (see Fig. 3.2). 

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