Malonato-bridged hexamethylenetetramine coordination polymers containing Mn(II) and Cu(II)

Two malonato-bridged hexamethylenetetramine coordination polymers, M₂(hmt)(H₂O)₂(mal)₂ [hmt?=?hexamethylenetetramine, mal?=?malonate(2-), M?=?Mn (1), Cu (2)] were prepared and structurally characterized. The isostructural complexes are orthorhombic, space group Imm2, with a?=?7.104(1), b?=?15.982(3), c?=?7.702(1)?Å, Z?=?2, D _calc?=?1.862?g?cm^?3(1) and a?=?6.962(3), b?=?15.500(7), c?=?7.627(3)?Å, Z?=?2, D _calc?=?2.047?g?cm^?3for 2. The transition metals are octahedrally coordinated by one nitrogen atom of an hmt ligand and five oxygen atoms of a water molecule and three malonate anions. The latter coordinate in chelating/bis-monodentate mode to give 2D layers with a (4,?4) topology, and which are pillared by bridging bidentate hmt ligands to generate an open 3D framework with channels extending in the [001] direction. Over the temperature range 5–300?K, 2 behaves paramagnetically, following the Curie–Weiss law χ_m(T???θ)?=?4.521(6)?cm³mol^?1K with a Weiss constant θ?=??4.8(2)?K.     

Copper(II) manganese(II) orthophosphate,Cu0.5Mn2.5(PO4)2

The title compound, Cu_0.5Mn_2.5(PO₄)₂, is a copper–manganese phosphate solid solution with the graftonite‐type structure, viz. (Mn,Fe,Ca,Mg)₃(PO₄)₂. The structure has three distinct metal cation sites, two of which are occupied by Mn^II and one of which accommodates Cu^II. Incorporation of Cu^II into the structure distorts the coordination geometry of the metal cation site from five‐coordinate square‐pyramidal towards four‐coordinate flattened tetrahedral, and serves to contract the structure principally along the c axis.     

Synthesis and properties of one-dimensional Ni(II) and Ni(II)Cu(II) complexes linked by hydrogen bond

Four dithiooxalato (Dto) bridged one-dimensional Ni(ll) and Ni(ll)Cu(ll) complexes (Me₆[14]dieneN₄)Ni₂(Dto)₂) (1), (Me₆[14]dieneN₄)CuNi(Dto)₂ (2), (Me₆[14]aneN₄)Ni₂(Dto)₂ (3), and (Me₆[14]aneN₄)CuNi(Dto)₂ (4), were synthesized. These complexes have been characterized by elemental analysis, IR, UV and ESR spectra. The crystal structure of complex3 was determined. It crystallizes in the monoclinic system, space group C2/c with a = 2. 2425(4) nm,b = 1.0088(2) nm,c= 1.4665(3) nm, β= 125.32(3)δ Z = 4;R = 0.076, R_w = 0.079. In the complex, Ni(1) coordinates four sulphur atoms of two Dto ligands in plane square environment. Ni(2) lies in the center of macrocyclic ligand. For Dto ligand, two sulphur atoms coordinate Ni(1), and O(1) coordinates Ni(2) and forms weak coordination bond. O(2) is linked to N(2) of macrocyclic ligand through hydrogen bond.     

The chemistry of adsorbed Cu(II) and Mn(II) in aqueous titanium dioxide suspensions

We studied the adsorption behavior of Cu(II) and Mn(II) on the surface of titanium dioxide over the pH range from 2.0 to 11.5. The titanium dioxide we used in these experiments was prepared by hydrolyzing TiCl₄ and had a surface area of 113.7 m² g⁻¹. All suspensions, which were 9.04 × 10⁻³ M in NaClO₄, contained 20 m² liter⁻¹ of oxide surface and divalent metal ion concentrations sufficient (at full adsorption from solution) to cover the available surface with one-half, one, and four layers of close-packed, hydrated ions. Both divalent ions began adsorption below titanium dioxide's isoelectric point (pH = 6.2). Cu²⁺ adsorption was accompanied by net OH⁻ uptake from solution and it was inferred that the titania surface also provided OH⁻ for Cu²⁺ adsorption. ESR spectra demonstrate the coexistence of two distinct forms adopted by these metal ions on the surface. A portion of the adsorbed metal ions occupies sites magnetically isolated one from another, as evidenced by the paramagnetic behavior of this form. The majority of the metal ions, however, exist in hydrous-metal-ion clusters in which spin-exchange coupling of the electron dipoles determines the magnetic behavior. Electrophoretic mobility measurements indicate that ions adsorbed at isolated sites exert a stronger influence on the electrophoretically measured charge of the suspension particles than ions in clusters. Even though these experiments were performed in the absence of oxygen, we observed the oxidation of a limited amount of the Mn(II) on the surface as low as pH = 5. Presumably this occurs as a result of electron transfer between photo-induced electron holes and Mn(II) on the surface.     

Komplexe von Cu(II), Zn(II), Ni(II) und Mn(II) mit N-m-Tolyl-p-methylbenzhydroxamsäure

The thermodynamic proton ligand and metal ligand stability constants of N-m-tolyl-p-methylbenzohydroxamic acid with Cu(II), Zn(II), Ni(II), and Mn(II) have been determined at 25° and 35° in several dioxane-water media. The pK _a and logK ₁ (logK ₂ or log ₂) varies linearly with the mole fraction of dioxane at a given temperature but not linearly with the reciprocal of dielectric constants of the medium. Values of G ^o, H ^o, and S ^o are tubulated. The stabilities of the complexes mostly follow the order of electron affinities of the metal ions. An attempt has been made to calculate the ligand field stabilization energy of the complexes.

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Mit 2 Abbildungen     

A one-dimensional Mn(II)-based metal organic oxide: structure and properties

A one-dimensional metal organic oxide of Mn(II), with formula [Mn₃(OH)₂(Hpdc)₂]_n (H₃pdc = 3,5-pyrazoledicarboxylic acid), was prepared via the hydrothermal method and its structure solved by single-crystal X-ray diffraction. The compound exhibits a three-dimensional framework structure, comprising three crystallographically unique Mn atoms bridged by OH ligands (O9 and O10) and O atoms from the Hpdc ligands, forming one-dimensional metal–organic oxide chains. Two kinds of magnetic exchange are observed: a strong antiferromagnetic intra-chain interaction, arising from the short distance between Mn(II) centers, and a ferromagnetic inter-chain interaction, due to the larger distances between the chains. The compound shows good photocatalytic activity for the decomposition of methylene blue in aqueous medium under simulated sunlight.     

Extremely long axial Cu-N bonds in chiral one-dimensional zigzag cyanide-bridged Cu(II)(-)Ni(II) and Cu(II)(-)Pt(II) bimetallic assemblies

Preparations, crystal structures, and spectral and magnetic properties of two new chiral one-dimensional cyano-bridged coordination polymers, [Cu(II)L2]M(II)(CN)].2H2O (M(II) = Ni(II) (1) and Pt(II) (2), L = trans-cyclohexane-(1R,2R)-diamine) have been presented. Complex 1 crystallizes in the monoclinic P2(1) space group with a = 9.864(4) A, b = 15.393(8) A, c = 7.995(4) A, beta = 110.32(3) degrees , V = 1138.4(10) A3, and Z = 2, while 2 crystallizes in the monoclinic P2(1) space group with a = 9.899(3) A, b = 15.541(4) A, c = 8.102(2) A, beta = 111.02(2) degrees , V = 1163.6(5) A3, and Z = 2. The unique zigzag cyano-bridged chains along the crystallographic b axis consist of alternate chiral [CuL(2)]2+ cations and square-planar [M(CN)4]2- anions. One side of the axial Cu-N(triple bond C) bond distances are 2.324(6) and 2.34(1) A with Cu-N[triple bond]C angles of 137.8(6) degrees and 138.2(9) degrees for 1 and 2, respectively. On the other hand, the opposite side of the axial Cu-N(triple bond C) bond distances are 3.120(8) and 3.09(1) A with significantly large bent Cu-N[triple bond]C angles of 97.9(5) degrees and 96.8(7) degrees for 1 and 2, respectively. The novel axial bonding features of extremely long semi-coordination Cu-N bonds are attributed to coexistence of pseudo-Jahn-Teller elongation and electrostatic interaction in the unique zigzag cyano-bridged chains. The characteristic bonding features with overlap between small 3d (Ni(II)) or large 5d (Pt(II)) and 3d (Cu(II)) orbitals results in larger shifts in XPS peaks of not only Cu2p(1/2) and Cu2p(3/2) but also Ni2p(1/2) and Ni2p(3/2) for 1 than those of 2, which is also consistent with weak antiferromagnetic interactions with Weiss constants of -5.31 and -5.94 K for 1 and 2, respectively. The d-d, pi-pi*, and CT bands in the electronic, CD, and MCD spectra for 1 and 2 in the solid state at room temperature are discussed from the viewpoint of magneto-optical properties.     

Complexes of Mn(II), Co(II), Ni(II) and Cu(II) with 4,4'-bipyridine and dichloroacetates

New mixed-ligand complexes with empirical formulae M(4-bpy)L₂·1.5H₂O (M(II)=Mn, Co), Ni(4-bpy)₂L₂ and Cu(4-bpy) L₂·H₂O (where: 4-bpy=4,4'-bipyridine, L=CC L2HCOO^-) have been isolated in pure state. The complexes have been characterized by elemental analysis, ir spectroscopy, conductivity (in methanol, dimethylformamide and dimethylsulfoxide solutions) and magnetic and x-ray diffraction measurements. The Mn(II) and Co(II) complexes are isostructural. The way of metal-ligand coordinations discussed. the ir spectra suggest that the carboxylate groups are bonded with metal(II) in the same way (Ni, Cu) or in different way (Mn, Co). The solubility in water is in the order of 19.40·10^-3÷1.88·10^-3ł mol dm^-3ł. During heating the hydrate complexes lose all water in one step. The anhydrous complexes decompose to oxides via several intermediate compounds. A coupled TG-MS system was used to analyse the principal volatile products of obtained complexes. The principal volatile products of thermal decomposition of complexes in air are: H₂O₂ ⁺, CO₂ ⁺, HCl⁺, Cl₂ ⁺, NO⁺ and other. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis of Cu(II) and Mn(III) Complexes Involving Derivatives of Pyridine

Two complexes with derivatives of pyridine as ligands were synthesized and characterized. From the reaction of 2-pyridinecarboxaldehyde oxime with Cu(OAc)₂ · H₂O afforded the complex C₂₀H₃₀N₆O₁₂Cu₃ (I), and the use of 3-hydroxy-2-pyridinecarboxylic acid with anhydrous MnCl₂ · 4H₂O led to the formation of another complex C₁₂H₁₄N₂OCl₂Mn (II). They were characterized by X-ray diffraction (CIF files CCDC nos. 568718 (I) and 1568880 (II)), NMR, IR and elemental analysis. For I: terigonal, space group R\(\bar 3\)/H, a = 42.548(3), c = 10.2774(9) Å, V = 16113(2) ų, Z = 18, ρ_calcd = 1.367 Mg/m³, the final R factor was R₁ = 0.0945, 6662 for reflections were observed with I > 2σ(I), wR = 0.162 for all data. For II: triclinic, Pī, a = 5.6174(9), b = 7.7259(13), c = 9.7160(16) Å, α = 70.444(3)°, β = 88.009(3)°, γ = 89.818(3)°, V = 397.09(11) ų, Z = 1, ρ_calcd = 1.840 Mg/m³, the final R factor was R₁ = 0.0281, 4280 for reflections were observed with I > 2σ(I), wR = 0.0775 for all data.     

Structure of Mn(II), Co(II), Ni(II), and Cu(II) complexes with triformylmethane

Previously unknown [ML₂(H₂O) _n ] bischelates, where M is Mn(II), Co(II), Ni(II), or Cu(II) and L is deprotonated triformylmethane, are studied by X-ray diffraction analysis. It is revealed that in the crystals of all compounds there are multiple hydrogen bonds linking bischelate molecules into polymer layers or a single framework. The character of the temperature dependence of the effective magnetic moment [ML₂(H₂O) _n ] indicates the existences of weak intracrystalline exchange interactions between the unpaired electrons of the paramagnetic centers.     

Hetero-binuclear chelates of Mn(II), Co(II) and Cu(II) o-cresolphthalein complexonates with other metal ions

Heterobinuclear metal chelates of Mn²⁺, Co²⁺ or Cu²⁺ and some transition metal ions with o-cresolphthalein complexone have been prepared and characterized. Elemental analyses are in agreement with proposed formulae. Thermal analyses (TGA and DTA) were used to determine the degradation products; some thermodynamic parameters were calculated. IR and UV-Vis spectra identified the mode of bonding between the metal ions and the ligand as well as its geometry. Magnetic moment determination and ESR spectra of the heterobinuclear complex revealed some antiferromagnetic interaction between the metal ions, which depends mainly on the two metal ions forming the chelate. Electrochemical studies of the complexes [DC-polarography and cyclic voltammetry (CV)] confirmed the existence and the nature of the metal ions in the chelate.     

Chelation behaviour of nitroso- pyrazolones with Mn(II), Co(II), Ni(II), Cu(II) AND Zn(II)

Infrared (IR), nuclear magnetic resonance (NMR), thermogravimetric analysis (TG), derivative thermogravimetric analysis (DTG), differential thermal analysis (DTA) and molar conductivity studies have been carried out on the chelates of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with 3-methyl- and 3-phenyl-4-nitroso-5-pyrazolones. The solid chelates were synthesized, separated, analyzed and their structures were elucidated. The data obtained show that almost all of the prepared chelates contain water molecules in their coordination sphere. The initial stage in the thermal decomposition process of these chelates shows the presence of water molecule, the second denotes to the intermediate products. The final decomposition products were found to be the respective metal oxides. The NMR spectrum of 3-methyl-4-nitroso-5-pyrazolone ligand shows the existence of the oxime rather than the nitroso form. 3-phenyl-4-nitroso-5-pyrazolone acts as a neutral bidentate ligand whereas 3-methyl-4-nitroso-5-pyrazolone acts as monobasic bidentate ligand bonded to the metal ions through the two oxygen atoms of the carbonyl and nitroso groups. The solid chelates prepared behave as non-electrolytes in DMF solution. The coordination numbers of the obtained chelates using 3-methyl-4-nitroso-5-pyrazolone are four on applying the mole ratio 1:1 and six on using 1:2 mole ratio. In case of using the ligand 3-phenyl-4-nitroso-5-pyrazolone the coordination number is six in both cases. This revised version was published online in August 2006 with corrections to the Cover Date.     

Solid-state thermal degradation behaviour of 1-D coordination polymers of Ni(II) and Cu(II) bridged by conjugated ligand

Monometallic complexes [Cudadb·yH₂O]_n (2) and [Nidadb·yH₂O]_n (3) and heterobimetallic complex [Cu_0.5Ni_0.5dadb·yH₂O]_n (4) {where dadbH₂ = 2,5-Diamino-3,6-dichloro-1,4-benzoquinone (1); y = 2–4; n = degree of polymerization} were characterized by elemental analysis, atomic absorption spectroscopy, infrared spectroscopy (FTIR) and powder X-ray diffraction. The thermal behaviour of the complexes was studied by thermal analysis (TG/DTA) under air as well as under helium atmospheres. The released gaseous products were investigated by evolved gas analysis performed by an online coupled mass spectrometer (TG/DTA-MS). Thermal degradation of 2 under helium atmosphere is distributed over five steps, whereas 3 and 4 exhibited only four degradation steps due to overlap of second and third degradation steps of into one major step. All the complexes exhibit three steps degradation under air. The complex 2 loses NH group in the second and HCl/Cl₂, CO groups simultaneously in third steps of decomposition under helium, whereas it loses NH and CO groups simultaneously in low temperature region of second step of degradation under air atmosphere as the loss of CO group is facilitated by air. EGA-MS under air and helium atmospheres shows that HCl, CO/CO₂ and (CN)₂ fragments are lost simultaneously at multiple steps, and not successively as predicted earlier. Rate of evolution of most evolved gases exhibits several maxima as a consequence of degradation followed by recombination reactions. Final residues under air and helium atmospheres correspond to the metal oxides and metals along with some carbonaceous matter.     

Thermal, spectral and magnetic behaviour of 2,3,4-trimethoxybenzoates of Mn(II), Co(II), Ni(II) AND Cu(II)

Four new complexes of 2,3,4-trimethoxybenzoic acid anion with manganese(II), cobalt(II), nickel(II) and copper(II) cations were synthesized, analysed and characterized by standard chemical and physical methods. 2,3,4-Trimethoxybenzoates of Mn(II), Co(II), Ni(II) and Cu(II) are polycrystalline compounds with colours typical for M(II) ions. The carboxylate group in the anhydrous complexes of Mn(II), Co(II) and Ni(II) is monodentate and in that of Cu(II) monohydrate is bidentate bridging one. The anhydrous complexes of Mn(II), Co(II) and Ni(II) heated in air to 1273 K are stable up to 505–517 K. Next in the range of 505–1205 K they decompose to the following oxides: Mn₃O₄, CoO, NiO. The complex of Cu(II) is stable up to 390 K, and next in the range of 390–443 K it loses one molecule of water. The final product of its decomposition is CuO. The solubility in water at 293 K is of the order of 10^–3 mol dm^–3 for the Mn(II) complex and 10^–4 mol dm^–3 for Co(II), Ni(II) and Cu(II) complexes. The magnetic moment values of Mn²⁺, Co²⁺, Ni²⁺ and Cu²⁺ ions in 2,3,4-trimethoxybenzoates experimentally determined in the range of 77–300 K change from 5.64–6.57 μB (for Mn²⁺), 4.73–5.17 μB (for Co²⁺), 3.26–3.35 μB (for Ni²⁺) and 0.27–1.42 μB (for Cu²⁺). 2,3,4-Trimethoxybenzoates of Mn(II), Co(II) and Ni(II) follow the Curie–Weiss law, whereas that of Cu(II) forms a dimer.     

Synthesis and Thermal Properties of 4,4'-bipyridine Adducts of Mn(II), Co(II), Ni(II) and Cu(II) Monochloroacetate

The complexes with the empirical formula M(4-bipy)(ClCH₂COO)₂ ×nH₂O (where: 4-bipy=4,4'-bipyridine, L=ClCH₂ COO^–, M (II)=Mn, Co, Ni, Cu) were prepared and characterized via the IR and electronic (VIS) spectra and conductivity measurements. Thermal decomposition of these compounds was studied. During heating in air dehydration processes occur. The anhydrous compounds decompose at high temperature to oxides. The principal volatile mass fragments correspond to: H₂O, CO₂, CH₃Cl, HCl, Cl₂ and other. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis and Thermal Decomposition of Mixed 2,4'-bipyridine-oxalato Complexes With Mn(II), Co(II), Ni(II) and Cu(II)

The mixed 2,4'-bipyridine-oxalato complexes of the formulae M(2,4'-bipy)₂ C₂ O₄ 2H₂ O (M (II)=Mn, Co, Ni, Cu; 2,4'-bipyridine=2,4'-bipy or L ; C₂ O^2– ₄ =ox) have been prepared and characterized. IR data show that the 2,4'-bipy coordinated with these metals(II) via the least hindered (4')N atom; that oxalate group acts as bidentate chelating ligand. Room temperature magnetic moments are normal for the orbital singlet states. The thermal decomposition of these complexes was investigated by TG, DTA and DTG in air. The endothermic or exothermic character of the decomposition of ML₂ (ox)2H₂ O was discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

New Complexes of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with 3,3-dimethylglutaric Acid

Conditions for the preparation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)3,3-dimethylglutarates were investigated and their quantitative composition, solubility in water at 293 K and magnetic moments were determined. IR spectra and powder diffraction patterns of the complexes prepared with general formula MC₇H₁₀O₄⋅nH₂O (n=0−2) were recorded and their thermal decomposition in air were studied. During heating the hydrated complexes of Mn(II),Co(II), Ni(II) and Cu(II) are dehydrated in one step and next all the anhydrous complexes decompose to oxides directly (Mn, Co, Zn) or with intermediate formation free metal (Ni,Cu) or oxocarbonates (Cd). The carboxylate groups in the complexes studied are bidentate. The magnetic moments for the paramagnetic complexes of Mn(II), Co(II), Ni(II) and Cu(II)attain values 5.62, 5.25, 2.91 and 1.41 M.B., respectively. This revised version was published online in August 2006 with corrections to the Cover Date.     

TG,DTA and electrical conductance properties of some Cu(II) AND Mn(II) bisazo- dianils complexes

The TG and DTA of a new series of Mn(II) and Cu(II) complexes with a number of newly prepared bisazo-dianil ligands were studied in the temperature range (20-700°C). The TG and DTG curves display to main steps, the first one within the temperature range (25-330°C) correspond to the elimination of water or and ethanol from the complexes. The second step within the range (350-625°C) is due to the decomposition of the complexes yielding the metal oxides as the final product. The rate constants of the dehydration and decomposition reactions were determined, from which some kinetic parameters were evaluated. The DTA curves show that the dehydration of the metal complexes is an endothermic reaction. In all cases the anhydrous metal complexes undergo exothermic decomposition reactions to give the metal oxide. The thermodynamic parameters (ΔE, ΔH, ΔS, ΔG) for the occurring processes are calculated. The electrical conductivities of the solid complexes were measured and the activation energy of the complex and its free ligand are also calculated. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis, thermal and other studies of 2,4'-bipyridine-dichloroacetato complexes of Mn(II), Co(II), Ni(II) and Cu(II)

Four new mixed ligand complexes were prepared by the reaction of title metal dichloroacetates and 2,4'-bipyridine. The general formulae of synthesized compounds are M(2,4'-bpy)₂(CCl₂HCOO)₂·nH₂O (where M(II)=Mn, Co, Ni, Cu; 2,4'-bpy=2,4'-bipyridine, n=2 or 4). The complexes have been isolated from aqueous media and characterized by chemical analysis, molar conductance (in MeOH, DMSO and DMF), magnetic, IR and VIS spectral studies. The nature of metal(II)-ligand coordination is discussed. The thermal behaviour of obtained complexes was studied by thermal analysis and TG-MS techniques in air. IR, X-ray powder diffraction and thermoanalytical data were used for the determination of solid intermediate products of the thermal decomposition. The principal volatile products of thermal decomposition of complexes were proved by mass spectroscopy: H₂O⁺, CO⁺ ₂, HCl⁺ ₂, Cl⁺ ₂, NO⁺ and other. This revised version was published online in July 2006 with corrections to the Cover Date.     

Preparation,IR spectra and thermal decomposition of malatoaquo complexes of Mn(II), Co(II), Ni(II) and Cu(II)

Reaction of malate ion with Mn(II), Co(II) and Ni(II) gave malatotriaquo complexes of these ions, while Cu(II) gave the malatoaquo complex. The structures of these complexes were predicted from elemental analysis and IR spectra. Thermal decomposition of the complexes using TG, DTG and DTA gave supporting evidence for the predicted structures. A correlation between the thermal stability of these complexes and the covalency of the MO bond was made.