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.     

Properties and structures of porphyrexides

The molecular and crystal structures of porphyrexides, viz., 4-amino-2-imino-(1) and (Z)-2-amino-4-bromoimino-5,5-dimethyl-4,5-dihydro-1H-imidazole 1-oxyls (7), and their diamagnetic precursors were determined. Compound 1 is kinetically unstable because it is oxidized with atmospheric oxygen to form (E)-1,2-bis[1-amino-1-(cyanoimino)-2-methyl-propan-2-yl]diazene 1,2-dioxide. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 441–447, March, 2006.     

Molecular magnet based on the FeII,III complex with squaric acid

The reaction of Fe^II and Fe^III salts with tetrabutylammonium squarate in an aqueous solution gives rise to a new molecular magnet (T _c = 8.6 K).     

Geometric,Spectroscopic, and Magnetic Characteristics of [Tris(1,10-phenanthroline)manganese](2+) 1,2;1′,2′-<Emphasis Type="Italic">trans</Emphasis>-Bis[nonahydro-<Emphasis Type="Italic">closo</Emphasis>-decaborate](2−) Bis(dimethylformamide)

[Tris(1,10-phenanthroline)manganese](2+) 1,2;1′,2′-trans-bis[nonahydro-closo-decaborate](2?) bis(dimethylformamide) containing the complex anion [MnPhen₃]²⁺ with the paramagnetic central Mn atom and the [B₂₀H₁₈]^2? anion formed by fusion of two closo clusters B₁₀H₉ was synthesized and characterized by single crystal X-ray diffraction and by IR, X-ray photoelectron, and Raman spectroscopy.     

Synthesis and Structure of Copper(II) Complexes with Methyl [(Pyrazolo-1-carbothioyl)-amino]propionate Derivatives

Methyl 3-[(3,5-dimethylpyrazole-1-carbothioyl)-amino]propionate (L¹) and the optically active derivative of natural monoterpene (+)-3-carene, (3bS,4aR)-3-[(3,4,4-trimethyl-3b,4,4a,5-tetrahydro-cyclopropa[3,4]cyclopenta[1,2-c]pyrazole-1-carbothioyl)-amino]propionate (L²), are synthesized. The paramagnetic CuL¹Cl₂ (I) and [Cu₂L² ₂Cl₄] (II) complexes are obtained. According to the X-ray diffraction data, in mononuclear complex I, the L¹ molecule performs a bidentate-cyclic function due to the coordination of the S atom of the C=S group and the N atom of the pyrazole cycle. The CuCl₂NS coordination polyhedron is a distorted tetrahedron. Two molecules of complex I form an associate due to weak Cu···S interactions. Compound II is binuclear due to the bridging function of two Cl^- ions, and analogous functions of the L¹ and L² ligands. The coordination polyhedron in complex II is CuCl₃NS. The _eff values for compounds I and II are equal to 1.81 and 1.79 _B, respectively, and are constant in the interval from 78 to 300 K, indicating that noticeable exchange interactions between unpaired electrons of the Cu²⁺ ions are absent. The EPR spectra of the complexes in the solid phase are examined.     

Electronic structure of the 3,3′-bis-[η5-π-1,2-dicarba-3-nickel(III)-closododecaborate](1-) anion, {NiIII[η5-π-(3)-1,2-B,C2H11]2}, in salts with different cations,in salts with different cations

The results of the spectral and magnetochemical studies of some salts of the “sandwich-like” paramagnetic anion {Ni^III[η⁵-π-(3)-1,2-B⁹C₂H₁₁]₂}^– (I) with the Cs⁺, (CH₃)₄N⁺, and (C₆H₅)₄P⁺ cations and the cation complex of Fe(II) and 1,10-phenanthroline, [Fe^IIPhen₃]²⁺, are reported. The solid-phase IR, Raman, and X-ray photoelectron spectroscopy methods and optical spectroscopy of solutions were used. The effective magnetic moments (μ_eff) of Ni(III) in anion (I) were measured by the Faraday technique and corrected for the diamagnetism of the aromatic cluster ligands 1,2-B₉C₂H ₁₁ ²⁻ (II). It is established that μ_eff is weakly dependent on the nature of the cation. The problems concerned with the nature of the metal-ligand bonds in metal-carborane systems like (I) are discussed. The hypothesis of the charge transfer from ligands (II) to the transition metal atoms is validated, the donor ability rows of the π-ligands are introduced, and the cluster structure of the systems under study is attested. Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 6, pp. 1060–1071, November–December, 1996. Translated by I. Izvekova     

Co(II), Ni(II) and Cu(II) Complexes with 1-(4-Hydroxyphenyl)-1H-1,2,4-Triazole

New complexes of Co(II), Ni(II), and Cu(II) with 1-(4-hydroxyphenyl)-1H-1,2,4-triazole (L) of the composition ML₂(H₂O)₂(NO₃)₂ · nH₂O (M = Co(II), n = 3; M = Ni(II), n = 0; M = Cu(II), n = 0) were synthesized and studied by photoelectron and IR spectroscopy, magnetochemistry, thermogravimetry, and X-ray powder diffraction analysis. The type of _eff(T) relationship suggests that paramagnetic centers in the Co(II) chloride and Cu(II) nitrate and bromide complexes are involved in antiferromagnetic exchange interactions. The exchange energy values were estimated by the molecular field method.     

Coordination compounds of cobalt(II), nickel(II), and copper(II) with 4-(3-hydroxyphenyl)-1,2,4-triazole: Synthesis and study

New Co(II), Ni(II), and Cu(II) complexes with 4-(3-hydroxyphenyl)-1,2,4-triazole (L) with the compositions [Co₃L₆(H₂O)₅(C₂H₅OH)](NO₃)₆ · 2H₂O · C₂H₅OH (I), [Ni₃L₆(H₂O)₆](NO₃)₆ · 2H₂O (II), and [M₃L₆(H₂O)₆](ClO₄)₆ · nH₂O (M = Co2⁺, n = 2 (III); Ni²⁺, n = 2 (IV); Cu²⁺, n = 0 (V)) are synthesized. The complexes are studied by X-ray structure analysis, X-ray diffraction analysis, UV and IR spectroscopy, and the statistical magnetic susceptibility method. All compounds have the linear trinuclear structure. Ligand L is coordinated to the metal ions by the N(1) and N(2) atoms of the heterocycle according to the bidentate bridging mode. In all compounds the coordination polyhedron of the metal atom is a distorted octahedron. The molecular and crystal structures of compound I, [Co₃L₆(H₂O)₆](ClO₄)₆ · 8C₂H₅OH (IIIa), and [Ni₃L₆(H₂O)₆](ClO₄)₆ · 8C₂H₅OH (IVa) are determined.     

Product of the reaction of cupric hexafluoroacetylacetonate with 1-hydroxy-3-imidazolines as immediate nitroxyl radical precursors

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1693–1694, July, 1988.