Stability of inorganic compounds

Enables the long-term stabilization of inorganic compounds... 

While bond dissociation energies are important in terms of the general understanding of physical chemistry, they are of little general use in predicting the stability of inorganic compounds, as they cannot be transferred between compounds. 

Procedures for the solidification and stabilization of inorganic compounds from mixed waste (using concrete or epoxy resin) to meet federal land ban restrictions have been outlined (40 CFR 268). This method may also abate the waste s chemical hazard and render a chemical-radioactive waste a radioactive waste. For example, waste lead citrate and uranyl acetate mixtures from electron microscopy can be solidified with port-land cement, which may be accepted for burial at a low-level radioactive waste site. 

One of the most important parameters that defines the structure and stability of inorganic crystals is their stoichiometry - the quantitative relationship between the anions and the cations [134]. Oxygen and fluorine ions, O2 and F, have very similar ionic radii of 1.36 and 1.33 A, respectively. The steric similarity enables isomorphic substitution of oxygen and fluorine ions in the anionic sub-lattice as well as the combination of complex fluoride, oxyfluoride and some oxide compounds in the same system. On the other hand, tantalum or niobium, which are the central atoms in the fluoride and oxyfluoride complexes, have identical ionic radii equal to 0.66 A. Several other cations of transition metals are also sterically similar or even identical to tantalum and niobium, which allows for certain isomorphic substitutions in the cation sublattice. 

In contrast to silicon, germanium has a well-established though limited chemistry of inorganic compounds in the +11 state which are of reasonable thermal stability though usually air-sensitive. Divalent organogermanium(II) species known at present fall into three groups ... 

Cheam, V. and H. Agemian. 1980. Preservation and stability of inorganic selenium compounds at ppb levels in water samples. Anal. Chim. Acta 113 237-245. 

In conclusion, when referring to the stability of a compound one must be precise. Many inorganic compounds can be prepared which are thermodynamically unstable but kinetically stable with respect to decomposition along various routes. In addition, inorganic compounds which react with oxygen or water can often be handled in inert atmospheres, where they can be regarded as perfectly stable. 

Three recent developments in the molecular orbital theory of electronic structure are particularly worthy of note. These are first, the successful analysis and quantitative interpretation of the spectra of unsaturated hydrocarbons and their simple derivatives 7 secondly, the development of a sound descriptive theory of the structures of electron-deficient compounds and thirdly, the elucidation of the principles underlying the structures and stabilities of inorganic metal complexes. These three topics are largely independent and each could occupy in itself a review of this length. However, the recent advances in the theory of inorganic metal complexes have been admirably covered in a recent review by... 

Supercritical fluids (SCFs) are fascinating media for the synthesis of inorganic compounds [1]. This is due in part to the tremendous versatility of these fluids, especially in providing access to unusual and kinetically stabilized solid phases. It should not be assumed, however, that either the techniques or the concepts are particularly new. In fact, most of the current techniques are really just derivatives of the methods developed in the last 50-100 years. There is broadening of interest in this field as inorganic chemists continue to search for new synthetic routes to unusual compounds. Several outstanding earlier reviews summarized the field to date and inspired new workers to enter the field [2-4]. However the most recent of these reviews is now over 12 years old and substantial new results justify a more current review. 

Alexander, J., Saeed K. and Thomassen Y. (1980). Thermal stabilization of inorganic and organoselenium compounds for direct electrothermal atomic absorption spectrometry. Anal. Chim. Acta, 120, 377. 

A high rate of degradation (TBT and DBT degraded to MBT and probably inorganic tin) was observed at +40 °C instability was also noted at +20 °C and to a lesser extent at +4 °C. With respect to stability tests carried out at - 20 °C, a shghtly higher uncertainty for MBT could be due to a change of extractabi-lity but this was not considered to affect the stability of this compound. On the... 

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