Existence of Yet Unknown Compounds

The most difficult problem in the radiochemistry of TAE is possible formation of a compound which has no analogs in chemistry of the known elements. The only example of a satisfactory solution to a similar problem in modem radiochemistry was the assignment of a cationic form of astatine [123]. It had required many years of experimentation despite the fact that the utilized At isotope had convenient half-life and was readily available in high enough activity to allow thorough experimentation. 

The researchers of a TAE would certainly enjoy finding that it forms a unique compound, not observed in chemistry of congeners. However, in practice, it would produce a stalemate situation with insuperable barriers, merely because it would be impossible to realize the required great number of different chemical experiments. Thus, with the TAEs, we are — and, in the near future, will be — concerned mostly with quantitative measurements of not too large differences in common properties of the congeners. Rare exceptions might be the experiments that simply ask, yes or no Still, we will have to be cautious about statistics. 

Zvara I, Chuburkov YuT, Belov VZ, Buklanov GV, Zakhvataev BB, Zvarova TS, Maslov OD, Caletka R, Shalayevsky MR (1970) 1 Inorg Nucl Chem 32 1885 Soviet Radiochem 12 530 Radiokhimiya 12 565 

Gaggeler HW, lost DT, Baltensperger U, Weber A, Kovacs A, Vermeulen D, Tiirler A (1991) Nucl Instr Meth Phys Res, A 309 201 

Zvara I (1973) In XXIVth Intemat congress pure applied chem, vol 6. Butterworth, London, p. 73 

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The modern techniques of quantum chemistry, in particular the ab initio methods, and the availability of supercomputers which perform several million operations in a second have given a variety of tools that help to predict experimental events with chemical accuracy [16]. The power of these methods has long been overlooked by orthodox chemists, since the methods of quantum chemistry have often only been used to predict a molecular property or the existence of a certain species after the fact. This is valuable for theoretical chemistry itself, but not for experimental chemistry in search of new compounds and new reactions. The value of theoretical predictions beyond the realm of theory is obvious only in new areas. In such a situation, theory can guide experimentalists by predicting the existence of yet unknown compounds, describing their electronic structure and properties, in particular their chemical behavior, and suggesting experiments that eventually may lead to the observation of these compounds. All this has been done in the theoretical investigations that represent the kernel of this review [4-15]. 

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