Igor E. Uflyand

1-amino-2-thiobenzimidazoleimines as novel ambidentate ligand systems

Azomethine derivatives of 1-amino-2-thiobenzimidazole (H2L) were synthesized and studied by IR and 1H NMR spectroscopy. Thiobenzimidazoline tautomeric form of these compounds was found to predominate in a solid state and DMSO solution. Novel mono-and binuclear metal chelates M(HL)2 and M2L2 (M = Ni(II), Cu(II), Co(II), Zn(II), Cd(II)) were synthesized on the basis of H2L derivatives and their composition and structures were established from IR, 1H NMR, EXAFS, and magnetochemical data. The composition of coordination sphere was shown to produce no effect on ferromagnetic exchange in binuclear Cu(II) complexes.

Review: recent advances in the chemistry of metal chelate monomers

Abstract This review summarizes recent advances in the chemistry of metal chelate monomers. Depending on the character of bonding of the metal to the chelating fragment, metal chelate monomers are divided into four main types: molecular metal chelates, intracomplex compounds, macrocyclic complexes, and polynuclear metal chelates. The synthetic methodologies for preparing metal chelate monomers are systematized. Special attention is paid to the effect of a metal on both the polymerization transformations of the metal chelate monomers and properties of the products formed. The bibliography includes papers published after 2010.

Chemical and electrochemical syntheses of the binuclear zinc and cadmium chelates based on the sterically hindered Schiff bases

Chemical and electrochemical syntheses of a series of the zinc(II) and cadmium(II) complexes were carried out on the basis of sterically hindered Schiff bases, which are the condensation products of 4,6-di-tert-butyl-2-aminophenol with the salicylaldehyde derivatives (H2L, H2L1). The structures and compositions of the synthesized binuclear complexes M2L2 and M2L21 where M = Zn(II) and Cd(II), were proved by the data of elemental analysis, IR spectroscopy, and 1H NMR spectroscopy. The structures of the Zn2L2 · 2Py and Zn2L2 · 2DMF dimers were proved by X-ray diffraction analysis. The electrochemical dissolution of zero-valence zinc and cadmium in methanol in the presence of equimolar amounts of H2L and H2L1 made it possible to isolate dimeric complexes of the corresponding metals of the composition M2L2 and M221.

Metal Chelate Monomers as Precursors of Polymeric Materials

The principal advances and problems of the preparation of polymeric materials based on metal chelate monomers containing metal chelate cycle and functionality are analysed. The data are systematized according to methods for preparing polymeric materials: homopolymerization, copolymerization, living and controlled polymerization, grafting polymerization, electropolymerization, polycondensation, as well as synthesis of dendrimers and hyperbranched polymers based on metal chelate monomers. Special attention is paid to the effect of a metal on both the synthesis mechanism and properties of the products formed. The principal applications of polymeric materials based on metal chelate monomers are considered.

Design and synthesis of coordination polymers with chelated units and their application in nanomaterials science

The advances and problems associated with the preparation, properties and structure of coordination polymers with chelated units are presented and assessed. The metalloligand strategy, and columnar-layered strategy, as well as approaches based on supramolecular building blocks and supramolecular building layers in the design of coordination polymers with chelated units are considered. The conventional (solvent evaporation, diffusion, hydro(solvo)thermal, ionothermal, microfluidic, surfactant-thermal, and in situ spacer methods as well as synthesis in supercritical CO2) and alternative (microwave-assisted, electrochemical, mechanochemical, and sonochemical methods) synthesis routes are described. Special attention is paid to the post-synthetic approaches to the preparation of coordination polymers with chelated units including post-synthetic modification, post-synthetic deprotection, and post-synthetic exchange. The thermal transformations of coordination polymers, resulting in the formation of nanocomposite materials, are considered. The bibliography includes the papers published within last five years.

METAL CHELATES OF NEW LIGANDS: 1,2-BENZOTHIAZINE-1,1-DIOXIDE DERIVATIVES

Abstract The novel chelates ML2 (M = Co, Ni, Cu, Zn) were obtained by the interaction of 3-benzoyl-4-hydroxy-1,2-benzothiazine-4(3H)-on-1,1-dioxide and 2-methyl-3-benzoyl-4-hydroxy-1,2-benzo-thiazine-4(3H)-on-1,1-dioxide with elemental metals (direct electrochemical synthesis) or their acetates (chemical synthesis) in methanol. The tetrahedral or polymeric-octahedral structures with a β-diketonate fragment are assigned based on IR and 1H NMR spectra. The studied ligands and their complexes are model compounds of molecules used as anti-inflammatory drugs.

Chemistry of Polymeric Metal Chelates

The polymeric metal chelates present class of chemical compounds including polymeric chain (organic, inorganic, mixed or biological nature) and metal chelate cycles. This direction of chemical science has appeared in the last decades of twentieth century at the junction of different fields of knowledge: coordination, polymer, physical, organic, colloid chemistry, biology, medicine and materials science. The need for accelerated development of this direction is confirmed by a rapid increase in the number of publications devoted to the study of polymeric metal chelates and their use as precursors of functional and nanoscale materials. Despite the variety of existing methods for synthesizing polymeric metal chelates, the main method still remains the direct interaction of metal compounds with chelating polymeric ligands. Therefore, the molecular design of chelating macroligands is an important, and in some cases, defining task both from the point of view of obtaining metal chelates with predetermined properties and structure, and their subsequent practical use. At the same time, in recent years a number of new methods have been developed for the preparation of polymeric metal chelates, primarily on the basis of metal chelate monomers, which allow one to obtain complexes in one stage with a targeted composition and structure. Progress in this field of chemistry is also associated with the emergence of new types of polymeric metal chelates, in particular, metal chelate dendrimers, star and hyperbranched polymers, as well as coordination polymers and supramolecular metal chelate polymers. Characteristic features, allowing reliably identify the polymeric metal chelates (PMCs) as particular class of chemical compounds, is the presence of the polymeric chain (organic, inorganic, mixed or biological nature) and metal chelate cycles [1]. This area is interesting because it is located at the intersection of the boundary areas of science—polymer and coordination chemistry. The combination of metal chelates and polymers in one chemical entity represents, on one hand, a fairly complex way, where in each case we have to use their methods of synthesis and study. PMCs are highly interesting materials with properties combining typical polymeric features with the properties of metal chelates. Due to the polymer chain, PMCs behave

Design Strategies of Metal Complexes Based on Chelating Polymer Ligands and Their Application in Nanomaterials Science

The advances and problems associated with the synthesis, properties and structure of metal complexes based on chelating polymer ligands are presented and assessed. The polymeric metal chelates (PMCs) are divided into molecular, intracomplex, macrocyclic and polynuclear types, which in turn are grouped according to the nature of the donor atoms (N,N-, N,О-, N,S-, О,О-, O,S-, S,S-, Р,Р-chelates, etc.). The main attention is focused on the similarities and differences between low and high molecular weight metal chelates, as well as the spatial organization of PMCs. The most important areas of research in the field of such compounds are highlighted. Thermal transformations of metal complexes based on chelating polymer ligands leading to the formation of nanostructured materials are considered. The bibliography includes the articles published after 2010.

Synthesis and structure of 2,2′-diaminodiphenylditelluride bis-imines

Bis-imines of 2,2′-diaminodiphenylditelluride and 2-tosylamino (9a) and 2-hydroxybenzaldehyde (9b) were prepared and studied by X-ray diffraction, heteronuclear (1H, 13C, 15N, and 125Te) magnetic resonance, and quantum chemical calculations (Pbe1pbe/DGDZVP). According to the X-ray diffraction data, compound 9b in the crystal phase has nonsymmetrical structure: one of the tellurium atoms forms hypervalent bonding with the adjacent oxygen atom, while the second one is not involved in such interaction. The NMR study showed the symmetric molecular structure of imines 9a,b in DMSO-d6 with the tellurium atoms interacting hypervalently with the C=N nitrogen atoms.

Copper complexes with N-aminotriazolethione azomethines: Structures and magnetochemical properties

Azomethine derivatives of 4-amino-1,2,4-triazole-3-thiones (H2L) and their metal complexes were obtained. The stabilities of the ligand conformers were calculated using quantum-chemical techniques. Ab initio (B3LYP/LANL2DZ) calculations of the complexes in the lower singlet and triplet states were performed with full geometry optimization. The structures and magnetochemical properties of the chelate complexes obtained were examined over a wide temperature range.