Balandin’s multiplet theory

The initial collective electronic theory of the fifties, in its simplest form, implied that the electrons and holes-controlled by the bulk structure—of the catalytic solid are available for reactants anywhere on the surface. It largely ignored the geometric factor inherent in Taylor s active site concept or in Balandin s Multiplet Theory. 

The nature of intermediate complexes on the surface of the catalyst can be considered using the "aromaticity principle" which was proposed by M.I.Temkin for explanation of the Balandin s multiplet theory of heterogeneous catalysis... 

In some doublet reactions the same products may be obtained from the same reactants but in different ways. Such reactions were referred to as olistomeric and the structural conditions of their appearance were determined on the basis of the multiplet theory (348). Thus, theoretically two cases of bond fission can take place in esterification, HO—COR + H—OR and H—OCOR HO—R. The tracer method shows that the first case is realized as a rule. The half-doublet scheme expresses such experiments. The doublet indexes for the reactions in solutions disintegrate into such schemes see Balandin (37). A complete system of doublet reactions for C, H, N, 0, S, and Cl (without their isotopes) has been obtained by the author (345). It is much more detailed than Table VII and amounts to 1500 types. It was obtained by exhaustive variation of atoms and bonds in the index by means of a specially developed method based on matrix algebra and combinatorial analysis. The significance of the obtained classification for organic catalysis is similar to that of the complete system of forms in crystallography, which was derived from the groups of symmetry by Fedorov and covers all possible forms (349). 

In making an assessment of Balandin s contribution to heterogeneous catalysis, it is necessary to divide his theories into two main parts and comment on each separately. The first contribution is that in the reactions of six-membered rings there is a correlation between ring and surface structure, which necessitates the fulfilment of a purely geometric condition for a catalyst to be active. The second is that catalytic reactions proceed according to the precepts of the multiplet theory. 

The multiplet theory represents the first attempt to classify catalytic reactions in purely steric terms. In this respect it is largely of academic interest. However, in the cases which have been described in detml, the theory has both provided an explanation of catalytic specificity, imd a quantitative assessment of the importance of surface geometry. Since the publication of the theory attempts have been made with other catalytic systems to assess the importance of the steric factor, and it is of interest in conclusion to trace briefly these developments, and their bearing on Balandin s conceptions. 

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