Yurii A. Maletin

Synthesis, spectral and electrochemical characteristics of asymmetrical iron(II) tris-dioximates

Abstract Meridianal- and axial-asymmetrical clathrochelate tris-dioximates of the FeD2D′(BF)2 and FeD3(BX)(Y) types (where D,D′=dioximes dianions, X=C6H5, F; Y=BF, Bn-C4H9, SnCl3) have been prepared by a stepwise synthesis from a planar-square macrocyclic precursors in the first case and from a semiclathrochelate compounds immobilized on the sorbent surface in the second one. The composition and structure of the isolated compounds have been established from elemental analysis data, polynuclear NMR, 57 Fe Mossbauer and FAB mass spectra. The structure parameters of α-benzyldioximate FeBd3(BF)(Bn-C4H9) · C6H5CH3 · 12–C8H16 (Fe–N distance – 1.89 A, bite angle – 38.6°, polyhedron distortion angle – 17.9°) were determined by X-ray crystallography. The electrochemical properties of the obtained complexes and their dependence on the nature of a ligand have been determined by cyclic voltammetry.

Macrobicyclic iron (II) oximehydrazonates and α-dioximates formed by capping with antimony (V) triorganyles: the first synthesis of antimony-containing clathrochelates

Abstract Antimony(V) triorganyles are proposed as efficient capping agents for the synthesis of oximehydrazonate and α-dioximate iron(II) clathrochelates.

Template synthesis, structure and electrochemistry of trinuclear iron(II) clathrochelate dioximates with ferrocenylboron fragments

Abstract Trinuclear macrobicyclic iron(II) complexes with alkyl, aryl and alicyclic dioximes have been synthesized by direct template reactions on the Fe 2+ ion using ferrocenylboronic acid (FcB(OH) 2 ) as cross-linking agent. The geometry of the distorted trigonal prismatic coordination polyhedron of encapsulated iron(II) ion for each obtained compound has been determined from Mossbauer ( 57 Fe) parameters using X-ray data for nioximate FeNx 3 (BFc) 2 · 2CCl 4 complex (Fe-N distance 1.91 A, bite angle 39.3°, polyhedron distortion angle 9.5°). The fac - and mer -isomers of the non-symmetrical methyl-glyoxine have been detected from the 13 C NMR spectrum. By electrochemical investigation, two independent redox centres were determined in molecules of synthesized complexes.

Dissociative electron transfer reactions

We consider recent data on dissociative electron transfer reactions in which the electron transfer causes practically concerted dissociation of the chemical bond in the reagent. We discuss considerable experimental data on reactions in the gas phase and in solutions, and also existing theoretical models for describing the kinetics of these complex processes.

Kinetics of electrode reduction of the tetrachlorocuprate(II) ion : an example of the concerted EC reaction mechanism

Abstract The kinetic parameters of reduction of [CuCl4]2− ion in acetonitrile at a conventional glassy carbon electrode and at a Pt micro-electrode (10 or 20 μm), have been determined taking into account the double-layer effect: standard rate constant k0S = 2.1 × 10−4 cm s−1, Gibbs energy of activation ΔG∗ = 26 kJ mol −1 , pre-exponential factor A ≈ 101 cm s−1 and transfer coefficient α = 0.31. Comparison with previous data on similar reactions suggests that the fast escape of chloride ions from the inner coordination sphere, which follows the electron transfer step, retards an EC reaction. If the two steps of the reaction are prectically inseparable, the barrier top broadens, resulting in a decrease in the frequency factor. A low value of the pre-exponential factor, in spite of a low activation barrier, is the main reason for the slowness of the reaction.