Table of contents

Data on the structure and reactivity of different nitrenium ions are generalised and described systematically. Various reaction pathways of these reactive intermediates resulted from their electronic structure are analysed. The attention is focused on the results of the 'direct' observation of the nitrenium ions and the role of the singlet–triplet conversion of these ions in chemical reactions.

Structural and functional features of HIV-1 integrase are considered and the state of the art in the quest for effective inhibitors of this enzyme is reported. The major classes of integrase inhibitors with known mechanisms of action as well as their in vitro and in vivo inhibitory activities are presented.

Various approaches to the synthesis of different types of binuclear phthalocyanines ('clamshell', planar, 'ball') and their polynuclear analogues are considered. Particular attention is focused on the behaviour of binuclear phthalocyanines in solutions.

The results of studies of weak spin–spin exchange interactions in binuclear copper(II) complexes with hydrazones based on saturated dicarbohydrazides in which the coordination polyhedra are connected by polymethylene spacers are generalised and systematically described.

The results of recent studies on the synthesis, properties and simulation of the electronic structures of metal diborides are described systematically. The discovery in 2001 of superconductivity in MgB₂ with the critical transition temperature T_c≈39 K can be considered as the starting point of intensive research on diborides. The discovery of cationic sublattice non-stoichiometry for a series of s-, p- and d-metal diborides with the AlB₂-type structure was among the most interesting results. For some non-stoichiometric diborides, the homogeneity regions can be rather broad. Metal vacancies present in the diborides cause significant changes in their physicochemical properties. Methods of synthesis of cation-deficient s-, p- and d-metal diborides are discussed and the results of experimental and theoretical studies of the effect of cationic vacancies on the properties of these compounds are analysed.