1,8-dihydroxyanthraquinone-Mg(II) complex: II. Spectrophotometric study. Determination of Mg(II)

The 1,8-dihydroxyanthraquinone (1,8-DHAn) shows a colored and fluorescent reaction with the ion Mg(II) in a hydroalcoholic and ammonical medium.In the present work we have studied spectrophotometrically the 1,8-DHAn-Mg(II) complex in a hydroethanolic and ammonical, 8 × 10^?4M medium. We found that the complex shows a maximum absorbance at 510 nm, and obeys a 1:1 stoichiometry with log K of 4.08.We propose a new method for the spectrophotometric determination of Mg(II) which is valid for concentrations between 0.25 and 2.00 ppm, and yields an error of 1.32%.     

Heptacopper(II) and dicopper(II)-adenine complexes: synthesis,structural characterization,and magnetic properties

The syntheses, crystal structures, and magnetic properties of two new copper(II) complexes with molecular formulas [Cu₇(μ₂-OH₂)₆(μ₃-O)₆(adenine)₆](NO₃)₂·6H₂O (1) and [Cu₂(μ₂-H₂O)₂(adenine)₂(H₂O)₄](NO₃)₄·2H₂O (2) are reported. The heptanuclear compound is composed of a central octahedral CuO₆ core sharing edges with six adjacent copper octahedra. In 2, the copper octahedra shares one equatorial edge. In both compounds, these basic copper cluster units are further linked by water bridges and bridging adenine ligands through N3 and N9 donors. All copper(II) centers exhibit Jahn–Teller distorted octahedral coordination characteristic of a d⁹ center. The study of the magnetic properties of the heptacopper complex revealed a dominant ferromagnetic intra-cluster interaction, while the dicopper complex exhibits antiferromagnetic intra-dimer interactions with weakly ferromagnetic inter-dimer interaction.     

Copper(II) and cobalt(II) hydroxypyridinecarboxylates: Synthesis, crystal structures, spectral and magnetic properties

Synthesis and characterization of six copper(II) and cobalt(II) octahedral complexes [M(6-OHpic)₂(H₂O)₂] (6-OHpic is 6-hydroxypicolinato), [M(2-OHnic)₂(H₂O)₂] (2-OHnic is 2-hydroxynicotinato), [Cu(6-OHnic)₂(H₂O)₂] (6-OHnic is 6-hydroxynicotinato) as well as [Co(H₂O)₆](6-OHnic)₂ are reported. Their characterization was carried out using elemental analysis, infrared, and magnetic measurements. Based on IR spectra, N,O-coordination of 6-OHpic (via the oxygen atom of the carboxyl group and the nitrogen atom of the pyridine ring), O,O-asymmetrically chelating coordination of the carboxyl groups as well as ionic coordination of 6-OHnic and chelating O,O-coordination (through the oxygen atom of the carboxyl group and the oxygen atom of the amide group) of keto(amide) tautomer of 2-OHnic were supposed. Moreover, crystal structures of 2-OHnicH and the complex [Co(2-OHnic)₂(H₂O)₂]) were determined by X-ray single crystal structure analysis. The system of hydrogen bonds predominantly stabilizes the keto(amide) tautomer of both 2-hydroxynicotinic acid and 2-OHnic anion in the cobalt(II) complex. Intermolecular hydrogen bonds (between the oxygen atom of the amide group and the hydrogen atom of the NH group) interconnect two neighbouring molecules of 2-OHnicH forming dimers. Cobalt(II) in complex [Co(2-OHnic)₂(H₂O)₂] has nearly a regular compressed tetragonal bipyramidal arrangement. Presented at the 1st International Conference “Applied Natural Sciences” on the occasion of the 10th anniversary of the University of Ss. Cyril and Methodius, Trnava, 7–9 November 2007.     

1,3-Bis(2-alkyltetrazol-5-yl)triazenes and their Fe(II), Co(II) and Ni(II) complexes: Synthesis,spectroscopy, and thermal properties. Crystal structure of Fe(II) and Co(II) 1,3-bis(2-methyltetrazol-5-yl)triazenide complexes

Complexes ML¹₂ and ML²₂, with M = Fe^II, Co^II, Ni^II, and 1,3-bis(2-R-tetrazol-5-yl)triazenide ligands L¹ (R = Me) and L² (R = ^tBu), have been synthesized by the reaction of corresponding 1,3-bis(2-R-tetrazol-5-yl)triazenes with metal(II) salts in basic media and characterized by IR, UV–Vis spectroscopy, thermal and X-ray diffraction analyses. Both 1,3-bis(2-R-tetrazol-5-yl)triazenes were found to deprotonate on coordination and act as tridentate chelating ligands forming distorted MN₆ octahedra around metal(II) cations.     

Synthetic, spectral and solution studies on imidazolate-bridged copper(II)-copper(II) and copper(II)-zinc(II) complexes

Synthesis, spectral and solution studies on 2-ethyl imidazolate-bridged (2-EtIm) homo-binuclear copper(II)-copper(II) and hetero-binuclear copper(II)-zinc(II) homologue are described. Magnetic moment values of homo-binuclear complexes indicate that the imidazolate group can mediate antiferromagnetic interactions. Optical spectra of hetero-binuclear complex at varying pH values suggest that the imidazolate-bridged complex is stable over the pH-range 7.15–10.0.     

N,N'-双水杨酰代乙二胺合铜(II)酸根和N,N'-1,2-双水杨酰代丙二胺合铜(II)酸根的Cu(II)-Co(II)双核酸合物的合成和磁性

本文合成了两个新型双核配合物, [Cu(Samen)Co(L)2]和[Cu(Sampn)Co(L)2], Samen^4^-表示N,N'-双水杨酰代乙二胺根阴离子,Sampn^4^-表示N,N'-1,2-双水杨酰代丙二胺根阴离子, L表示5-硝基-1,10-菲咯啉(NO2-Phen)。经元素分析, IR和电子光谱等推定配合物具有酚氧桥结构,Cu(II)及Co(II)的配位环境分别为平面四方及畸变八面体构型。测定了配合物(4-300K)的变温磁化率, 并用最小二乘法和自旋Hamiltonian算符,H=2JS1.S2-DSzl导出的磁方程拟合, 求得交换参数为J=-4.39(Samen)和-3.59cm^-^1(Sampn), 表明两个Cu(II)-Co(II)双核配合物中有弱的反铁磁性超交换相互作用。     

Chromotropism studies on copper(II) compounds. Part II. Dinuclear copper(II) complexes with triply-bridged hydroxo,acetate, and halo ligands

Abstract

Two triply-bridged dinuclear copper(II) complexes of formula [LCu(μ-OH)(μ-OAc)(μ-X)CuL]X?0.5H₂O where L is a bidentate ligand of N-(pyridine-2-ylmethyl)propane-2-amine and X=Cl, 1 and Br, 2 were synthesized and characterized by elemental analyses, spectroscopic techniques (IR, UV–Vis, EPR), thermal analysis, conductance measurements, and single-crystal X-ray structure determination. The structures of both complexes are similar. The complexes show a distorted square-pyramidal arrangement around each copper(II) ion with a CuN₂O₂X chromophore in which both copper(II) ions are connected by a hydroxo bridge and a triatomic syn-syn carboxylato bridge in equatorial positions and a halide ion bridge at the axial site. The chromotropism behavior of the complexes, including solvato-, thermo-, and halochromism, were investigated in detail. Their halochromism was investigated in the pH range of 2.0–11.0 by visible absorption spectroscopy. The reversible color variations from blue to colorless are attributable to deprotonation and protonation of the ligands. The complexes show reversible thermochromism in solution due to dissociation and recombination of ligands to copper ions.     

Zinc(II) and mercury(II) complexes with Schiff bases: syntheses,spectral, and structural characterization

Schiff bases o-vanilidene-1-aminobenzene (HL¹) and o-vanilidene-2-methyl-1-aminobenzene (HL²) lead to the formation of mono- and bis-[(Cl)Zn(L¹)] (1), [(Cl)Zn(L²)] (2), [(Cl)Hg(L¹)] (3), [(Cl)Hg(L²)] (4), [Zn(L¹)₂] (5), [Zn(L²)₂] (6), [Hg(L¹)₂] (7), and [Hg(L²)₂] (8) complexes by reactions of zinc(II) and mercury(II) chlorides in different mole ratio(s). Complexes 1–8 have been characterized by elemental analyses (Zn, Hg, C, H, Cl, and N), melting point and spectral (IR, ¹H-NMR), PXRD, molar conductivity measurement, and TGA. Conductivity measurements suggest non-electrolytes. Structural compositions have been assigned by mass spectral studies. Four-coordinate geometry may be assigned to these complexes tentatively. Structural study reveals that in 1–4 two metal centers are held together by two bridged (μ₂-Cl) chlorides, whereas 5–8 contain two bidentate Schiff-base ligands around one metal-producing monomers.     

Ca(II) and Ba(II) methyl carbazate energetic complexes: syntheses,crystal structures,and properties

New energetic materials, [Ca(MCZ)₃(H₂O)₂](ClO₄)₂ and {[Ba₂(MCZ)₄(H₂O)₂(μ₁-ClO₄)₂(μ₂-ClO₄)₂]_0.5}_n, are synthesized and tried as alternatives to common primary explosives. Both the crystal structures were determined by single-crystal X-ray diffraction. The crystal of [Ca(MCZ)₃(H₂O)₂](ClO₄)₂ belongs to the monoclinic, P2₁/c space group, a = 14.168(3) Å, b = 8.5938(18) Å, c = 18.889(4) Å, β = 111.234(2)°, V = 2143.8(8) Å³, ρ = 1.6893 g cm^?3, and {[Ba₂(MCZ)₄(H₂O)₂(μ₁-ClO₄)₂(μ₂-ClO₄)₂]_0.5}_n belongs to the triclinic, P-1 space group, a = 7.166(2) Å, b = 10.461(2) Å, c = 11.738(4) Å, α = 110.563(5)°, β = 93.799(2)°, γ = 96.864(3)°, V = 812.4(4) Å³, ρ = 2.185 g cm^?3. Their thermal stabilities were investigated by differential scanning calorimetry (DSC), and exothermic peak temperatures with a heating rate of 10 °C min^?1 are 249.7 and 181.7 °C, respectively. Non-isothermal reaction kinetics parameters were calculated via both Kissinger’s method and Ozawa-Doyle’s method to work out E_K = 124.6 kJ mol^?1, lgA_K = 10.38, E_O = 126.7 kJ mol^?1 for the calcium complex and E_K = 100.3 kJ mol^?1, lgA_K = 9.50, E_O = 102.6 kJ mol^?1 for the barium complex. Additionally, the critical temperatures of thermal explosion, ΔS^≠, ΔH^≠, and ΔG^≠ were calculated as ?231.2 J K^?1 mol^?1, 120.417 kJ mol^?1, 236.728 kJ mol^?1 for the calcium complex and ?230.6 J K^?1 mol^?1, 96.723 kJ mol^?1, 195.938 kJ mol^?1 for the barium complex. As for their explosive nature, sensitivities toward impact and friction were tested. Both [Ca(MCZ)₃(H₂O)₂](ClO₄)₂ and {[Ba₂(MCZ)₄(H₂O)₂(μ₁-ClO₄)₂(μ₂-ClO₄)₂]_0.5}_n are insensitive to friction (>360 N); their impact sensitivities are acceptable (20 and 13 J). Both compounds are energetic complexes.     

Magnetic,epr and SOD studies of some Cu(II)-Cu(II), Cu(II)-Ni(II) and Cu(II)-Zn(II) imidazolate bridged complexes

Magnetic, spectroscopic and superoxide dismutase activity of imidazolate bridged [(Salala)Cu-Im-Cu(Salala)]Na, [(Salala)Cu-Im-Zn(Salala)]Na and [(Salala)Cu-Im-Ni(Salala)]Na (Salala=Salicyledenealiniate, Im=Imdiazolate) are described. The epr and electronic spectra of related mononuclear complexes, viz., [(Salala)Cu-OH(2)] and [(Salala)Cu-ImH] also described. Appearance of a half-field signal in polycrystalline and decrease in mu(eff) per copper(II) ion indicate super exchange coupling between copper(II) ion in [(Salala)Cu-Im-Cu(Salala)]Na binuclear complex. A pH-dependent epr and UV-vis study of 50% aqueous DMSO solution of binuclear complexes suggest that the complexes are stable in narrow pH range.     

Polymetallic complexes: Part V. ONNO tetradentateN,N′-bis(acetoacetanilide)-1, 3-diaminopropane complexes of cobalt(II), copper(II) and zinc(II)

Summary Ten complexes of composition [Co₂L₂X₄] (X=Cl, Br, NO₃ or ClO₄); [Cu₂L₂(NO₃)₄]; [Zn₂L₂X₄ (X=Cl, SCN or ClO₄); [CuCl₂L] and [ZnBr₂L] have been synthesized, where L is the ONNO tetradentate ligand,N,N-bis(acetoacetanilide)-1,3-diaminopropane. The complexes have been characterised by elemental analysis, conductance, magnetic susceptibility, molecular weight and i.r., and electronic spectral measurements.Author to whom all correspondence should be directed.     

Polymetallic complexes: part VII. bis(benzoin)thiocarbohydrazide complexes of cobalt(II), copper(II) and zinc(II)

Summary Complex compounds of cobalt(II), copper(II) and zinc(II) with bis(benzoin)thiocarbohydrazide have been synthesised. The ligand is probably coordinated to the metal ions as an ONNO tetradentate donor, giving rise to binuclear metal complexes with a halogen bridge. Structures have been assigned on the basis of analyses, conductance, magnetic susceptibility, i.r., electronic spectra and molecular weight data.     

Derivatographische untersuchungen über die thermische zersetzung von pyridin,isochinolin, αα-dipyridyl und o-phenantrolin,bzw. bichromatoder chromat-ion enthaltenden metallkomplexen: II. Zink(II)-, cadmium(II)- und mangan(II)-komplexe III. Quecksilber(I und II)-, uranyl-, thorium-, lanthan- und eisen-komplexe

Complexes were prepared of zinc(II), cadmium(II), manganese(II) mercury (I and II), uranium, thorium(IV), lanthanum and iron ions with pyridine, isoquinoline, αα-dipyridyl, or o-phenanthroline ligands and bichromate or chromate ions as described on pp. 205–207 of Ref. 1.     

Complexes of aminobenzylamines. part II. Complexes ofo-aminobenzylamine with palladium(II) and platinum(II)

Summary The reactions of K₂[MX₄] (M = Pd^II or Pt^II and X = Cl or Br) witho-aminobenzylamine (o-aba) have been studied in neutral aqueous solutions. Two types of complexes were isolated from these studies: [MLX₂] and [ML₂]X₂. Elemental analyses, conductivity measurements, i.r. and visible spectra suggest polymeric structures for [MLX₂] with the ligand,o-aba = L, acting as a bridge, and/or mononuclear structures for [ML₂]X₂.     

Preparation,infrared, Raman and N.M.R. spectra of N,N′-Diethylthiourea complexes with zinc(II), cadmium(II) and mercury(II) halides

Several complexes of N,N′-diethylthiourea (Dietu) with zinc(II), cadmium(II) and mercury(II) halides were prepared and characterized by i.r. (4000–60 cm^?1), raman (400–60 cm^?1), in the solid state and n.m.r. and conductometric methods in solution. The complexes Zn(Dietu)₂X₂, Cd(Dietu)₂X₂ (X ? Cl, Br, I) and Hg(Dietu)₂X₂ (X ? Br, I) are tetrahedral species in which intramolecular ? NH …? X interactions have been observed. The 1:1 mercury(II) complexes, Hg(Dietu)X₂ (X ? Cl, Br), appear to have a dimeric tetrahedral halide-bridged structure in the solid state. In all these complexes N,N′-diethylthiourea is sulphur-bonded to the metal.