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.     

A Study of Competitive Coordination of Benzochalcogenazole Ligands by Heteronuclear NMR Spectroscopy

Complexes of 2-methyl(phenyl)benzo-1,3-tellurazole and 2-methyl(phenyl)benzo-1,3-selenazole with tungsten pentacarbonyl and boron trifluoride were studied by heteronuclear NMR spectroscopy (¹H, ¹³C, ⁷⁷Se, and ¹²⁵Te). The coordination mode of the ambident ligand can be determined from the coordination shifts of the ¹²⁵Te and ⁷⁷Se NMR signals: upfield at coordination via Te and Se atoms and downfield at N coordination.     

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.     

A Model System for the Study of Competitive Coordination in Aminoheterocyclic Complexes. Molecular and Crystal Structure of 2-Amino-1-methyl-Benzoimidazolium Chloride Hydrate

2-Amino-1-methyl-benzoimidazolium chloride hydrate was structurally characterized by X-ray diffraction analysis. Its crystal is built from organic cations, chloride anions, and molecules of crystallization water, which are united through a related system of hydrogen bonds. In the organic cation, the proton is localized at the N atom of the pyridine type.     

Exchange Processes in Pb(II) Complexes

A novel technique of 2D exchange NMR with suppression of the coherent magnetization transfer is suggested for the collection of useful chemical information on the basis of standard 2D exchange spectroscopy. In this technique, only one nucleus of the coupled spin system involved in chemical exchange is excited (so-called multiplet selectivity or semiselective excitation). In this case, the multiplet structure of the selectively irradiated nucleus behaves as an uncoupled multisite system.     

Luminescent complexes with ligands containing C=N bond

Data on luminescent complexes with azomethine ligands are generalized and systematized. The synthesis and luminescent properties of complexes with acyclic and cyclic azomethines are considered.     

Tribochemically active chelate complexes of salicylideneimines

N-Alkylsalicylideneimines and their complexes with 3d metals were obtained by chemical (from metal salts) and electrochemical methods (from metals in the zero oxidation state). The compounds obtained were characterized by IR and ¹H NMR spectroscopy and X-ray diffraction analysis. According to crystallographic data, nickel bis(chelate) exists in the trans-planar configuration. A friction test revealed that the tribotechnical characteristics of lubricating formulations are substantially enhanced in the presence of N-alkylsalicylideneiminates.     

New octahedral Zn<Superscript>II</Superscript> and Cd<Superscript>II</Superscript> complexes based on azo derivatives and azomethines of pyrazole-5-thione

New metal chelates of Zn^II and Cd^II (ML₂) based on (4Z)-3-methyl-1- phenyl-5-thioxo-1,5-dihydro-4-H-pyrazol-4-one quinolin-8-ylhydrazone (HL¹) and (4Z)-5- methyl-2-phenyl-4-[(quinolin-8-ylimino)methyl]-2,4-dihydro-3H-pyrazole-3-thione (HL²) were synthesized. The structures of the metal chelates were studied by EXAFS and NMR (¹H, ¹³C, and ¹¹¹Cd) spectroscopy. The structure of the Cd(L¹)₂ complex was established by X-ray diffraction analysis. The complexes have pseudooctahedral structures with the N₄S₂ ligand environment.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 623–629, March, 2005.     

Accounting for Edge-Plasma Parameter Dynamics at JET Divertor Sputtering Estimation during Edge-Localized Modes

Physics of Atomic Nuclei - The sputtering of tungsten divertor tiles at the JET ITER-like wall (ILW) during edge-localized modes (ELMs) is one of the main sources of tungsten impurity in the core...