Table of contents

A new phenomenon, spin catalysis, i.e., stimulation of chemical reactions by removing the prohibitions imposed for reasons of electron angular momentum (spin) of reactants is considered. The physical and chemical mechanisms of this phenomenon are discussed. The nature of spin catalysts, the quantitative measure of catalytic effects and the types of chemical reactions susceptible to spin catalysis are considered.

The review surveys the pathways of formation of crystalline oligomeric oxoalkoxides M_mO_n(OR)_p, which are products of partially controlled (or uncontrolled) hydrolysis, oxidation, thermal decomposition of mono- and bimetallic alkoxides of the ortho series M(OR)_n and M_mM'_n(OR)_p or elimination of ethers from these compounds. The physicochemical properties of oxoalkoxides (solubility, the behaviour in solutions, volatility, etc.) differ considerably from the properties of the corresponding alkoxides. Hence, oxoalkoxides can be considered as immediate precursors of oxide materials produced by sol–gel technology. The M_mO_n(OR)_p compounds are classified according to the sizes of associates. The crystal chemistry of alkoxides is discussed.

The published data on the synthesis, reactivities and applications of organic, coordination and organometallic compounds containing a (Me₃Si)₃Si group are generalised and systematised.

Kinetic data on intramolecular abstraction of hydrogen atoms in alkyl, alkoxyl and peroxyl radicals are generalised and analysed. It is shown that the activation energies of these reactions are affected by ring strain. The kinetic parameters of mono- and bimolecular elimination reactions are compared. The difference between the activation energies of these reactions is interpreted using the model of intersecting parabolas. The same model is used to discuss the results of analysis of cyclisation of alkyl radicals; the ring strain energy is shown to play an important role in the activation of these reactions. It is noted that the difference between the electron affinities of the C, N and O atoms is clearly manifested in the cyclisation of aminyl and ω-formylalkyl radicals. The kinetic parameters of cyclisation and bimolecular radical addition reactions are compared. The experimental data on the transfer of the vinyl and aryl groups in alkyl radicals are analysed.

The review is concerned with analysis of the results obtained in the kinetic and mechanistic studies on decomposition of energetic materials (explosives, powders and solid propellants). It is shown that the state-of-the art in this field is inadequate to the potential of modern chemical kinetics and chemical physics. Unsolved problems are outlined and ways of their solution are proposed.