Co(III) complexes with optically active bis(menthane), pinano-para-menthane, carano-para-menthane, and bis(carane) propylenediaminodioximes

Novel optical ligands bis(menthane) (H₂L¹), pinano-para-menthane (H₂L²), and carano-para-menthane (H₂L³) propylenediaminodioximes are obtained. Diamagentic Co(III) complexes of the composition Co(HL¹)Cl₂ (I), Co(HL²)Cl₂ (II), Co(HL³)Cl₂ (III), and Co(HL⁴)Cl₂ · H₂O(IV) are synthesized by reactions of CoCl₂ with H₂L¹, H₂L², H₂L³ and bis(carane) propylenediaminodioxime (H₂L⁴) in ethanol in air. The crystal and molecular structures of compound I is determined by X-ray diffraction analysis. The crystals are monoclinic with the unit cell parameters a = 7.8385(3) Å, b = 11.4074(6) Å, c = 14.9509(6) Å, β = 104.278(2)°, V = 1295.57(10) ų, Z = 2, ρ(calcd) = 1.367 g/cm³, F(000) = 564, M = 533.41, space group P2₁. The crystal structure of complex I consists of individual mononuclear molecules. The Co³⁺ ion coordinates four N atoms of tetradentate cycle-forming anionic ligand and two Cl atoms. The coordination polyhedron of Cl₂N₄ is a distorted octahedron. The ¹³C and ¹H NMR spectra of the complexes synthesized confirm coordination of four N atoms of a ligand.     

Synthesis and structure of new copper(II) coordination compounds with 8-quinoline aldehyde semicarbazones and thiosemicarbazones

Copper(II) salts were reacted with various quinoline aldehyde chalcogensemicarbazones to yield compounds formulated as Cu(HL)X₂ · nH₂O (I: HL = quinoline aldehyde thiosemicarbazone (HL¹), X = ClO₄, n = 2; II: HL = quinoline aldehyde 4-C₂H₅-thiosemicarbazone (HL^1a), X = NO₃, n = 0; III: HL = quinoline aldehyde semicarbazone (HL²), X = ClO₄, n = 3 and IV: HL = quinoline aldehyde 4-Ph-semicarbazone (HL^2a), X = NO₃, n = 1). Regardless of the reagent ratio, the products were compounds having the metal: ligand ratio of 1: 1, where the organic ligand was coordinated tridentate in a molecular form. Single-crystal X-ray diffraction showed that, depending on the chalcogen atom in the organic ligand (S or O), the substituent in the 4th position (at the terminal nitrogen atom), and the specifics of the acido ligand, complexes I–IV had appreciably differing molecular structure organizations. The structures of I and III are formed by a 1D charged coordination polymer, ClO ₄ ^? anions, and water molecules and may be described by the formula [Cu(HL)(H₂O)(ClO₄)] _n (ClO₄) _n · nH₂O. Copper(II) coordination polyhedra in I and II are (4 + 2) and (4 + 1 + 1) tetragonal bipyramids, respectively. In II and IV, the structures are monomeric and can be described as [Cu(HL^1a)(NO₃)₂] with the metal coordination polyhedron shaped as a (4 + 1) tetragonal pyramid in II and as [Cu(HL^2a)(H₂O)(NO₃)](NO₃) with the metal coordination polyhedron shaped as a (3 + 2) trigonal bipyramid in IV. The structure of II is built of molecular complexes, each comprising, apart from ligand HL^1a, two monodentate coordinated NO ₃ ^? groups. The oxygen atom of one anion together with the NNS donor atom set of ligand HL^1a form the base, and the oxygen atom of the other anion is in the apex of the coordination polyhedron. In IV, the structure is ionic and built of NO ₃ ^? anions and [Cu(HL^2a)(H₂O)(NO₃)]⁺ complex cations, where a cationic coordination polyhedron has a trigonal-bipyramidal configuration with organic ligand HL^2a positioned along the long edge. The bipyramidal base is made up by the oxygen atoms of the coordinated water molecule and monodentate nitrato group and the nitrogen atom N2 of the azomethyne group.     

Three new Cu(II)-Ln(III) heterometallic coordination polymers constructed from quinolinic acid and nicotinic acid: Synthesis, structures, and magnetic properties

Three new Cu(II)-Ln(III) heterometallic coordination polymers based on two N-heterocyclic carboxylic ligands, {[LnCu(L¹)₂(L²)(H₂O)₂]·mH₂O} _n (Ln = La(1), Nd(2), Gd(3), m = 2 (for 1), 1 (for 2, 3), H₂L¹ = quinolinic acid, HL² = nicotinic acid), have been synthesized and characterized. 1 has a two-dimensional (2D) layer structure with a Schl?fli symbol of (4⁴.6²), while complexes 2 and 3 are isostructural and have three-dimensional (3D) structures with a Schl?fli symbol of (3.4.5)₂(3².4².5².6¹⁴.7⁴.8³.9)(3².6³.7) of 3-nodal net. Magnetic investigations suggest that antiferromagnetic coupling exists between Nd^III and Cu^II in 2, while weak ferromagnetic coupling between Gd^III and Cu^II in 3. The difference of magnetic properties between 2 and 3 has been discussed.     

Transformation of a ditopic Schiff base nickel(II) nitrate complex into an unsymmetrical Schiff base complex by partial hydrolytic degradation: structural and density functional theory studies

A new Schiff base complex [Ni(H₂L¹)(NO₃)](NO₃) (1) (H₂L¹ = 3-[N,N′-bis-2-(5-bromo-3-(morpholinomethyl) salicylideneamino) ethyl amine]) was synthesized from reaction of the ditopic ligand H₂L¹ with Ni(NO₃)₂ in anhydrous MeOH. Complex 1 is stable in the solid state, but prone to hydrolysis. Recrystallization of 1 from wet MeOH led to the isolation of a novel unsymmetrical complex [Ni(HL²)(NO₃)](NO₃) (2) (HL² = 2-[(2-(2-aminoethylamino) ethylimino) ethyl)-5-bromo-3-(morpholino methyl) salicylidene amine]). X-ray single-crystal analysis of complex 2 showed that complex 1 had undergone partial decomposition of one imine bond. In contrast, the Schiff base complex [Ni(HL³)](NO₃) (3) (H₂L³ = N,N′-bis(5-methyl-salicylidene) diethylenetriamine) was stable in wet methanol, and the single-crystal structure of 3 showed that the Ni(II) center was coordinated in an unsymmetrical square planar geometry. Density functional theory calculations were performed in order to obtain a geometry-optimized model of complex 1, in which the Ni(II) center was coordinated in a similar manner as that in complex 3. The thermodynamic parameters were calculated, in order to rationalize the difference in hydrolytic reactivity between complexes 1 and 3.     

Silver(I) Compounds with Perfluorinated Aromatic Thiols C6F5C6F4SH,C10F7SH,and C6F5SH as Precursors for Silver Nanoparticles

Silver(I) compounds with perfluorinated aromatic thiols (4-nonafluorodiphenylthiol C₆F₅C₆F₄SH (HL¹), 2-heptafluoronaphthalenethiol C₁₀F₇SH (HL²), and pentafluorothiophenol C₆F₅SH (HL³), namely AgL¹ (I), AgL² (II), AgL³ (III), were prepared. The thermal properties of compounds I–III and the composition of thermolysis products were studied. By powder X-ray diffraction and electron microscopy, it was shown that thermolysis of compounds I–III under argon and thermolysis of compound III in air yield Ag nanoparticles.     

Synthesis,crystal structures,and properties of copper(II) dicarboxylate complexes with [bis(2-pyridylcarbonyl)amido]

Four new complexes, [Cu₂(Bpca)₂(L¹)(H₂O)₂] · 3H₂O (I), [Cu₂(Bpca)₂(L²)(H₂O)₂] (II), [Cu₂(Bpca)₂(L³)] · 2H₂O (III), [Cu₂(Bpca)₂(L¹)(H₂O)] · 2H₂O (IV) (Bpca = bis(2-pyridylcarbonyl)amido, H₂L¹ = glutaric acid, H₂L² = adipic acid, H₂L³ = suberic acid, H₂L⁴ = azelaic acid) have been synthesized and characterized by single-crystal X-ray diffraction methods (CIF files CCDC nos. 1432836 (I), 1432835 (II), 817411 (III), and 817412 (IV)), elemental analyses, IR spectra. Structural analyses reveal that compounds I, II, and IV have similar structures [Cu(Bpca)]⁺ units bridged by dicarboxylate forming dinuclear units, whereas the dinuclear of compound III are edge-shared through two carboxylate oxygen atoms of different suberate anions. Hydrogen bonds are response for the supramolecular assembly of compounds I to IV. The temperature-dependent magnetic property of III was also investigated in the temperature range of 2 to 300 K, and the magnetic behaviour suggests weak antiferromagnetic coupling exchange.     

Nickel(II) and copper(II) complexes of unsymmetrical tetradentate reduced Schiff base ligands

Two new reduced Schiff base ligands, [HL¹ = 4-{2-[(pyridin-2-ylmethyl)-amino]-ethylimino}-pentan-2-one and HL² = 4-[2-(1-pyridin-2-yl-ethylamino)-ethylimino]-pentan-2-one] have been prepared by reduction of the corresponding tetradentate unsymmetrical Schiff bases derived from 1:1: 1 condensation of 1,2-ethanediamine, acetylacetone and pyridine-2-carboxaldehyde/2-acetyl pyridine. Four complexes, [Ni(L¹)]ClO₄ (1), [Cu(L¹)]ClO₄ (2), [Ni(L²)]ClO₄ (3), and [Cu(L²)]ClO₄ (4) with these two reduced Schiff base ligands have been synthesized and structurally characterized by X-ray crystallography. The mono-negative ligands L¹ and L² are chelated in all four complexes through the four donor atoms to form square planar nickel(II) and copper(II) complexes. Structures of 3 and 4 reveal that enantiomeric pairs are crystallized together with opposite chirality in the nitrogen and carbon atoms. The two Cu^II complexes (2 and 4) exhibit both irreversible reductive (Cu^II/Cu^I; E_pc, −1.00 and −1.04 V) and oxidative (Cu^II/Cu^III; E_pa, +1.22 and +1.17 V, respectively) responses in cyclic voltammetry. The electrochemically generated Cu^I species for both the complexes are unstable and undergo disproportionation.     

Syntheses, structures, and properties of the Co(II), Ni(II), and Cu(II) complexes with 5-carboxy- and 5-methoxycarbonylpyrazoles

New cobalt(II), nickel(II), and copper(II) complexes based on 5-methoxycarbonyl-3-me-thylpyrazole (MePzCOOMe), [Co(MePzCOOMe)₂(H₂O)₂](NO₃)₂ (I), [Ni(MePzCOOMe)₂(H₂O)₂] (NO₃)₂ (II), and [Cu(MePzCOO)₂(H₂O)] · 3H₂O (III), were synthesized. The compounds were studied by X-ray diffraction analysis, IR spectroscopy, and static magnetic susceptibility. The molecular and crystal structures of complexes I and III were determined by X-ray structure analysis.     

Synthesis and molecular and crystal structures of binuclear complexes of Sm(III), Eu(III), Gd(III), Tb(III), and Dy(III) nitrates with 4,4,10,10-tetramethyl-1,3,7,9-tetraazospiro[5.5]undecane-2,8-dione

Binuclear complexes of Sm(III), Eu(III), Gd(III), Tb(III), and Dy(III) nitrates with 4,4,10,10-tetramethyl-1,3,7,9-tetraazospiro[5.5]undecane-2,8-dione (C₁₁H₂₀N₄O₂, SC)—[Sm(NO₃)₃(SC)(H₂O)]₂(I), [Eu(NO₃)₃(SC)(H₂O)]₂ (II), [Gd(NO₃)₂(SC)(H₂O)₃)]₂(NO₃)₂ (III), [Tb(NO₃)₃(SC)(H₂O)]₂ (IV), [Dy(NO₃)₃(SC)(H₂O)]₂ (V), are synthesized, and their X-ray diffraction analyses are carried out. The crystals of complexes I–V are monoclinic: space group P2₁/n for III and P2₁/c for I, II, IV, and V. In centrosymmetric coordination complexes II, III, IV, and V, the Ln atoms are coordinated by two O(1) and O(2) atoms of two molecules of the SC ligands bound by a symmetry procedure (1 ? x, ?y, 1 ? z), three bidentate nitrate anions, and a water molecule. The coordination numbers of the metal atoms are equal to 9, and the coordination polyhedra are considerably distorted three-capped trigonal prisms, whose bases include the O(1), O(2), O(12) and O(3), O(7), O(9) atoms. The dihedral angle between the bases of the prism is 18°, and that between the mean planes of the side faces is 55°–71° for I, 17° and 55°–71° for II, 16° and 55°–70° for IV, and 16° and 55°–70° for V. The Sm...Sm distance in complex I is 9.44 Å, Eu...Eu in II is 9.42 Å, Tb...Tb in IV is 9.36Å, and Dy...Dy in V is 9.36Å. The gadolinium atom in complex III is coordinated by two oxygen atoms of two ligand molecules bound by a symmetry procedure (?x, ?y + 1, ?z + 1), two bidentate nitrate anions, and three water molecules. One of the nitro groups in compound III is localized in the external coordination sphere of the metal. The coordination number of gadolinium is 9, and the coordination polyhedron is a significantly distorted three-capped trigonal prism, whose base includes the O(1), O(2), O(7) and O(4), O(5), O(9) atoms. The dihedral angle between the bases of the prism is 22.8°, and that between the mean planes of the side faces is 53°–72°. The Gd...Gd distance in complex III is 9.17 Å.     

Cobalt(II) and copper(II) complexes with chiral pyrazolylquinoline,a derivative of terpenoid (+)-3-carene. Catalytic activity in ethylene polymerization reaction

Coordination compounds [CoLCl₂] (I), [CuLCl(NO₃)] (II), CuL(NO₃)₂ (III), and CuLCl₂ (IV) (where L is a chiral pyrazolylquinoline—a derivative of terpenoid (+)-3-carene) were synthesized. X-ray diffraction data showed that crystal structures I and II are built of mononuclear acentric molecules. In the molecule of complex I, the Co₂₊ ion coordinates two N atoms of bidentate cycle-forming ligand L and two Cl atoms. The coordination polyhedron of Cl₂N₂ is a distorted tetrahedron. For complex I, μ_eff = 4.50 μ_B, which corresponds to a high-spin configuration d ⁷. In the molecules of II(1), II(2) (which are diastereoisomers of complex II), each Cu²⁺ ion coordinates two N atoms of bidentate cycle-forming ligand L, the Cl atom, and two O atoms of bidentate cyclic NO ₃ ^? ion. The ClN₂O₂ coordination polyhedra are tetragonal pyramids with different degrees of distortion. The structure of complex II consists of supramolecular clusters, i.e., isolated chains incorporating the molecules of II(1) and II(2). The values of μ_eff for II–IV correspond to the d ⁹ configuration. The results of EPR and IR study suggest that complex III contains the O₄N₂ polyhedron, whereas complex IV contains the Cl₂N₂ polyhedron. Complexes I and IV were found to show a high catalytic activity in ethylene polymerization reaction.     

Di- and tetranuclear heterometallic CuII-LnIII complexes (Ln = Gd and Dy): Synthesis, structure and magnetic properties

Four 3d-4f heterometallic complexes, [CuⅡ LnⅢ (bpt) 2 (NO 3 ) 3 (MeOH)] (Ln = Gd, 1; Dy, 2; bptH = 3,5-bis(pyrid-2-yl)-1,2,4- triazole), [CuⅡ 2 LnⅢ 2 (μ-OH) 2 (bpt) 4 Cl 4 (H 2 O) 2 ]·6H 2 O (Ln = Gd, 3; Dy, 4), have been synthesized under solvothermal conditions. X-ray structural analyses reveal that 1 and 2 are isostructural while 3 and 4 are isostructural. In each complex, the copper and gadolinium or dysprosium ions are linked by two triazolate bridges and form a CuⅡ -LnⅢ dinuclear unit. The intramolecular Cu-Ln distances are 4.542, 4.525, 4.545 and 4.538 for 1, 2, 3 and 4, respectively. Two dinuclear CuLn units are bridged by two OH- groups into the zig-zag tetranuclear {CuⅡ 2 LnⅢ 2 } structures with the Ln(Ⅲ) Ln(Ⅲ) distances of 3.742 and 3.684 for 3 and 4, respectively. Magnetic studies show that the antiferromagnetic CuⅡ-LnⅢ interactions occur in 1 (J CuGd = 0.21 cm-1 ) and 2. The antiferromagnetic interaction occurs in complex 3 with J CuGd = 0.82 cm-1 and J GdGd = 0.065 cm-1 , while dominant ferromagnetic interaction occurs in complex 4.     

Nickel(II) complexes of polyhydroxybenzaldehyde N4-thiosemicarbazones: synthesis, structural characterization and antimicrobial activities

Nickel(II) complexes with 2,3-dihydroxybenzaldehyde N4-substituted thiosemicarbazone ligands (H₃L¹–H₃L⁴) have been synthesized and characterized with the aim of evaluating the effect of N4 substitution in the thiosemicarbazone moiety on their coordination behavior and biological activities. Two series of nickel(II) complexes with the general formulae [Ni(H₃L)(H₂L)]ClO₄ and [Ni₂(HL)₂] were characterized by analytical and spectral techniques. The molecular structure of one of the complexes, namely, [Ni(H₃L⁴)(H₂L⁴)]ClO₄ was established by single crystal X-ray diffraction studies. The crystal structure of this complex revealed that two H₃L⁴ ligands are coordinated to nickel(II) in different modes; one as a neutral tridentate ONS ligand and the other is as a monoanionic tridentate (ONS^?) ligand. The antimicrobial activities of the compounds were tested against 25 bacterial strains via the disc diffusion method, and their minimum inhibitory concentration (MIC) and minimum microbicidal concentration were evaluated using microdilution methods. With a few exceptions, most of the compounds exhibited low-to-moderate inhibitory activities against the tested bacterial strains. However, the complexes [Ni₂(HL³)₂] (7) and [Ni₂(HL⁴)₂] (8) indicated higher inhibitory activity against Salmonella enterica ATCC 9068 (MIC values 15.7 and <15.7 μg/ml, respectively), compared with gentamicin as the positive control (MIC 25 μg/ml). Complex (7) also inhibited Streptococcus pneumoniae more efficiently (MIC 31.2 μg/ml), compared with gentamicin (MIC > 50 μg/ml). The toxicities of the compounds were tested on brine shrimp (Artemia salina), where no meaningful toxicity level was noted for both the free ligands and the complexes. The cytotoxicities of the compounds on cell viability were determined on MCF7, PC3, A375, and H413 cancer cells in terms of IC₅₀; complexes [Ni(H₃L³)(H₂L³)]ClO₄ (3), [Ni₂(HL³)₂] (7) and [Ni₂(HL⁴)₂] (8) exhibited significant cytotoxicity on the tested cell lines.     

Synthesis, characterization and crystal structures of palladium(II) complexes containing neutral, one and twofold deprotonated 1,2,4-triazine species

The synthesis and characterization of three new palladium(II) complexes of 4-amino-6-ethyl-1,2,4-triazine-3-thion-5-one (AETTO, H₃L), [PdCl₂(H₃L)]·H₂O (1), [Pd₂Cl₂(H₂L)(PPh₃)₃]NO₃·2CH₃CN (2) and [Pd(HL)(PPh₃)₂] (3), are reported. All the synthesized compounds are air-stable and were characterized by elemental analyses, IR, NMR spectroscopy and mass spectrometry. In addition, the molecular structures of the complexes have been determined by X-ray single crystal diffraction. On the basis of the crystallographic data, the neutral ligand in 1 and the deprotonated ligands in 2 and 3 act as bidentate NS donors. The singly deprotonated ligand in 2 acts as a bridging agent between two metal centers in the binuclear Pd^II-complex.     

Synthesis and structure of bis(monohaloacetates) of tris(5-bromo-2-methoxyphenyl)antimony

Tris(5-bromo-2-methoxyphenyl)antimony bis(monohaloacetates) [(5-Br)(2-MeO)C₆H₃]₃Sb[OC(O)CH₂X]₂, X = Cl (I), Br (II), I (III) have been synthesized by the reaction of tris(5-bromo-2-methoxyphenyl)antimony with chloro-, bromo-, and iodoacetic acids in the presence of hydrogen peroxide. According to X-ray analysis the antimony atom in I–III has a distorted trigonal-bipyramidal coordination.     

Cobalt(II) complexes with pentadentate Schiff bases 2,6-diacetylpyridine hydrazones: Syntheses and structures

Seven new cobalt(II) complexes based on the Schiff bases, 2,6-diacetylpyridine bis(isonicotinoylhydrazone) (H₂L¹) and 2,6-diacetylpyridine bis(nicotinoylhydrazone) (H₂L²), are synthesized and studied by X-ray diffraction analysis: [Co(H₂L¹)(NCS)₂] · 2.25H₂O (I), [Co(H₂L²)(NCS)₂] · CH₃OH (II), [Co(H₂L²)(NCS)(H₂O)]NCS (III), [Co(H₄L¹)(NCS)₂](NO₃)₂ · 2H₂O (IV), [Co(H₄L¹)(NCS)₂][Co(NCS)₄] · 0.75H₂O (V), [Co(H₄L²)(NCS)₂][Co(NCS)₄] · 1.75H₂O (VI), and [Co(H₂L²)(NCS)(CH₃OH)]₂[Co(NCS)₄] · 2CH₃OH (VII) (CIF files CCDC 941186 (I), 1457906 (Ia), 1457905 (II), 941187 (III), 1457907 (IV), 1457908 (V), 1457909 (VI), and 941188 (VII)). The organic ligands in the complexes act as pentadentate neutral H₂L or doubly protonated (H₄L)²⁺ coordinated through the same set of donor atoms N₃O₂. In all compounds I–VII, the coordination polyhedron of the Co²⁺ ion in a complex with the Schiff bases has a shape of a pentagonal bipyramid. The hydrazones are arranged in the equatorial plane of the bipyramid. Its axial vertices are occupied by the nitrogen atoms of the NCS￣ anions in compounds I, II, and IV–VI and by the nitrogen atoms of NCS￣ and oxygen of the water molecule in compound III or methanol in compound VII. The NO ₃ ^- anions or [Co(NCS)₄]^2￣ complex anions obtained by the reactions are involved along with the NCS￣ anions in the formation of compounds IV–VII.     

Microwave-assisted synthesis,crystal structures,and in vitro antibacterial studies of zinc(II) and nickel(II) complexes with Schiff bases

The syntheses of a mononuclear zinc(II) complex [ZnCl(L¹)(Amp)] (I) and a mononuclear nickel(II) complex [Ni(L²)(HL²)](BF₄) · 0.5H₂O (II) (HL¹ = 4-methyl-2-[(4-methylpyridin-2-ylimino) methyl]phenol, HL² = 4-methyl-2-[(pyridin-2-ylmethylimino)methyl]phenol; Amp = 2-amino-4- methylpyridine) were prepared under microwave irradiation. The complexes were characterized by a combination of elemental analyses, and IR and electronic spectra. Their structures were further confirmed by single crystal X-ray crystallography (СIF files CCDC nos 1437737 (I), 1437738 (II)). The Zn atom in the monomeric complex I is in tetrahedral coordination. The Ni atoms in the dimeric complex II are in octahedral coordination. Crystals of the complexes are stabilized by hydrogen bonds. In order to evaluate the biological activity of the complexes, in vitro antibacterial against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa was assayed. The complexes have strong activity against Bacillus subtilis.     

Heterometallic complexes of macrocyclic oxamide with polycarboxylates: Syntheses,crystal structures,and magnetic properties

Three complexes with the formula [Co(Ip)(CuL)(H₂O)₂] · H₂O (I), [Co(Ip)(NiL)(H₂O)₂] · H₂O (II), [Co(CuL)₂(Hbtc)(H₂O)] (III), (H₂Ip = m-isophthalic acid; H₂L = 2,3-dioxo-5,6,14,15-dibenzo-1,4,8,12-tetraazacyclo-pentadeca-7,13-dien; H₃Btc = 1,3,5-benzenetricarboxylic acid) were synthesized and structurally characterized by elemental analysis, IR and UV spectroscopy. Single-crystal X-ray analyses reveal that the complexes I and II contain neutral heterometallic binuclear CoM (for I and II, M = Cu, Ni, respectively) moieties, and complex III contains discrete neutral trinuclear CoCu₂ moieties. The structures of I–III consist of two-dimensional supramolecular architecture formed by strong O-H…O intermolecular hydrogen bonds. Furthermore, the magnetic properties of complex I were investigated and discussed in detail.     

Synthesis, structures, and thermolysis of new heterometallic cobalt, nickel, and copper complexes with the [Ru(NO)(NO2)4(OH)]2− anion as a ligand

Heterometallic complexes with pyridine-N-oxide (PyO), Ru(NO)(NO₂)₄(OH)Ni(PyO)₂(H₂O)] · CH₃COCH₃ (I), [{Ru(NO)(NO₂)₂(μ-NO₂)₂(μ-OH)Co}₂(μ-PyO)] · H₂O · CH₃COCH (II), and [Ru(NO)(NO₂)₄(OH)Cu(PyO)₂ (III), are isolated in the reactions of Na₂[Ru(NO)(NO₂)₄(OH)] with nitrates of the corresponding metals in the presence of the organic ligand. The compounds synthesized are characterized by IR spectra, thermal analysis, and X-ray diffraction analysis. Depending on the M²⁺ cation, the ruthenium cation is coordinated through the bidentate (III, Cu²⁺) or tridentate (I, Ni²⁺ and II, CO₂₊) mode involving the bridging OH group and one or two NO₂ groups. The thermal decomposition of complex II results in the formation of a Co_0.5Ru_0.5 solid solution, which is thermodynamically stable under the decomposition conditions. The thermolysis of complexes I and III in a hydrogen atmosphere leads to the formation of metastable solid solutions.     

The Cu(II) complexes with bis(pyrazole-1-yl)methane and its derivatives: Synthesis,crystal structure,and magnetic properties

The procedures for the synthesis of the Cu(II) complexes with bis(pyrazole-1-yl)methane (L¹), bis(3,5-dimethyl-4-bromopyrazole-1-yl)methane (L²), and bis(3,5-dimethyl-4-iodopyrazole-1-yl)methane (L³) of the composition Cu₂(L¹)₂Br₄ (I), Cu₂(L²)₂Cl₄ (II), Cu(L³)(NO₃)₂ (III), and Cu(L³)(H₂O)(NO₃)₂ · 2H₂O (IV) were developed. The organic ligands in the above complexes are coordinated to Cu(II) in a bidentate cyclic type through the N(2), N(2′) atoms of the pyrazole rings. The molecular and crystal structures of L², L³, II, III, and IV were determined by X-ray diffraction. The study of the μ_eff(T) function in a temperature interval 2–300 K showed that compound I, which exhibited ferromagnetic exchange interactions in the chains, undergoes transition to antiferromagnetic state with weak ferromagnetism. The exchange antiferromagnetic interactions predominate in compound II.     

Synthesis, crystal structures and electrochemical properties of CoIII complexes with hexadentate ligand containing thioether-amidopyridyl donor set

Two new cobalt(III) complexes of the hexadentate ligand [1,4-bis[o-(pyridine-2-carboxamidophenyl)]-1,4-dithiobutane] (H₂bpctb) with N₄S₂ donor set atoms have been synthesized. A reaction of Co(CH₃COO)₂·4H₂O with (H₂bpctb) leads to the formation of [Co^III(bpctb)]PF₆ (1) having a CoN₂(pyridine)N′₂(amide)S₂(thioether) coordination by symmetric bpctb^2? ligand. A similar reaction under slightly different conditions, however, gives [Co^III(L ^a )(L ^b )] (2), resulting from a C–S bond cleavage reaction triggered by an acetate ion as a base, having CoN₂(pyridine)N′₂(amide)S(thioether)S′(thiolate) coordination. These two Co(III) complexes have been characterized by elemental analyses and spectroscopic methods, and the crystal and molecular structures of [Co^III(bpctb)]PF₆ (1) in the form of the solvate (1·MeOH·H₂O) and of [Co^III(L ^a )(L ^b )] (2) have been determined by X-ray crystallography. The Co atoms of both complexes exhibit distorted octahedral geometry. The electrochemical investigation of [Co(bpctb)]PF₆·MeOH·H₂O (1·MeOH·H₂O) and [Co^III(L ^a )(L ^b )] (2) by cyclic voltammetry reveals a reversible Co^III–Co^II redox process at E _1/2 = ?0.32 V (ΔE _p = 80 mV); for 1, and E _1/2 = ?0. 87 V (ΔE _p = 70 mV) for 2.