Kinetic Studies of the Catalytic Effect of Cobalt(II) Ions on the Substitution Reactions of the Ethylenediaminetetraacetatocobalt(III) Complex

The rate for the substitution reaction of Co(edta)^? with ethylenediamine was greatly enhanced by the presence of an excess of Co(II) ion in solution. The rate constant is (13±2) M^?-sec^?1 at μi=0.10M LiClO₄, pH=11.1, [en]=0.10M and T=25°C. The mechanism for the reaction is discussed on the basis of the Marcus theory for outer-sphere processes corrected for electrostatic effects. This catalytic effect was not observed when the Co(II) was present in small amount due to the stability of the Co(edta)^?2 complex toward substitution. The rate constant for direct substitution of Co(edta)^? under the same conditions has also been measured and the value is (3.66±0.40)×10^?4sec^?.     

Syntheses of N,N′-Bis(salicylideneiminoethyl)oxamidatodicopper(II), N,N′-Bis(salicylideneiminoisopropyl)-oxamidatodicopper(II), and N,N′-Bis(2-pyridylideneiminopropyl)oxamidatodicopper(II) Nitrate and Corresponding Perchlorate

Reactions of coordinated functional groups were carried out as follows: The product formed by reaction of A-1a

1 The four new complexes are shown as A-3a, A-3b, B-3a, and B-3b (cf. Fig. 1), and other related complexes are shown as A-1a, A-1b, A-2a, A-2b, B-n, B-1, B-4, and B-5 (cf. Fig. 2)

or A-1b with copper(II), reacts with salicylaldehyde to give A-3a or A-3b, respectively. And the product formed by reaction of B-1 with copper(II), reacts with pyridine-2-aldehyde to give B-3a or B-3b. The four binuclear copper(II) complexes thus isolated as the new compounds have been characterized by elemental analyses, u.v. and i.r. spectra, magnetic susceptibility, and electronic conductivity measurements. Attempts to exchange the reactants with one another were unsuccessful.     

Crystal structure of (N,N,N′,N′-tetramethyl-1,2-diaminoethane)(1,1,1-trifluoro-6-methyl-2,4-heptanedionato)copper(II) perchlorate

The solvatochromic compound [Cu(tfmh)Me₄en]ClO₄ (tfmh^? denotes the anion of 1,1,1-trifluoro-6-methyl-2,4-heptanedione) was prepared and its structure has been determined from three-dimensional X-ray diffraction data. The structure consists of discrete [Cu(tfmh)Me₄en]⁺ monomeric units and perchlorate ions. The copper(II) ion is surrounded by the two nitrogen atoms of the diamine molecule and the two oxygen atoms of the β-dionato anion. The N,N,N′,N′-tetramethyl-1,2-diaminoethane, Me₄en, coordinates as bidentate ligand through the nitrogen atoms and adopts the gauche conformation and λ configuration. The CuN₂O₂ chromophore is virtually planar. The compound crystallizes in the monoclinic system (space group P2₁/c) with a = 11.9520(2), b = 14.6600(2), c = 17.2240(4) Å, β = 135.72(2)°, Z = 4 and V = 2107.01(7) ų.     

Komplexe mit N,N,N′,N′-Tetrakis(2-hydroxybenzyl)ethylendiamin (H4tben). Kristallstruktur von Ti(tben)

Complexes with N,N,N′,N′-Tetrakis(2-hydroxybenzyl)ethylenediamine (H₄tben). Crystal Structure of Ti(tben) The complexes of N,N,N′,N′-tetrakis(2-hydroxybenzyl)-ethylenediamine with titanium(IV), vanadium(IV), manganese(IV), and tin(IV) were synthesized and characterized by mass spectrometry. The Mössbauer date were evaluated for the tin compound. The molecular structure of the titanium(IV) complex was determined by X-ray structural analysis, crystallographic data see “Inhaltsübersicht”.     

An Expedient Synthesis of Novel N,N′‐Diglycosylguanidine Derivatives in the Presence of Hg(II)

The reactions of N,N′‐diglycosythiourea with 2‐amino‐benzothiazoles in the presence of Hg(II) (HgCl₂ or HgO) for the synthesis of N‐(4/6‐substituted‐benzothiazol‐2‐yl)‐N′,N″‐diglycosylguanidines have been reported.     

Kristall- und Molekülstruktur von N,N′-o-Phenylen-bis-(N″,N′-diethyl-N‴-benzimidoyl-thioureato)nickel(II)

Crystal and Molecular Structure of N,N′-o-Phenylen-bis-(N″,N″-diethyl-N?-benzimidoyl-thioureato)nickel(II) The structure of the title compound has been determined by an X-ray structure analysis. The compound crystallizes in the monoclinic space group C2/c with a = 38.896, b = 14.326, c = 11.121 Å, β = 102.33° and Z = 8. The solution of the structure was performed by Patterson methods. The final R value was R = 0.053 for 2260 observed reflections. The coordination geometry is nearly planar. The ligator atoms show as a necessity a cis arrangement. The chelate rings deviate from planarity. The phenyl rings and the phenylene fragment are significantly twisted in respect to the chelate rings.     

Synthesis and Crystal Structure of 1D Coordination Polymer of N,N＇-Bis（3-pyridylmethyl）-1,4-benzenedicarboxamide and Cobalt（Ⅱ） Nitrate

A noval cobalt(II) coordination polymer, {[Co(bpmb)(H₂O)₂(C₂H₅OH)₂]·(NO₃)₂}‐ (1). where bpmb=N,N′‐bis(3‐pyridylmethyl)‐1,4‐benzenedicarboxamide, was synthesized by self‐assembly of the two topic ligands with cobalt nitrate in ethanol solution, and characterized structurally by X‐ray crystallography analysis. The crystal data belong to triclinic, space group P1 with cell parameters a=0.8911(3) nm, b=0.9042(3) nm, c= 1.0068(3) nm, α= 73.083(5)°, β=81.069(5)°, γ=76.210(5)°, R₁=0.0518, wR₂=0.0947. The results of structure analysis indicate that each bpmb ligand coordinates two Co(II) atoms and each metal atom is in octahedral coordination geometry with four oxygen atoms of two ethanol and two water molecules, two nitrogen atoms from two different bpmb ligands in trans position forming an infinite 1D chain‐like structure. There BTC hydrogen bonding and π‐π stacking interaction among these chains, leading to supramolecular formation with 3D net structure.     

A complex containing three different kinds of Ru—N bonds: ethoxydinitronitrosyl(N,N,N′,N′‐tetramethylethylenediamine‐κ2N,N′)ruthenium(II)

The octahedral title compound, [Ru(C₂H₅O)(NO)(NO₂)₂(C₆H₁₆N₂)], crystallizes in the rhombohedral space group P3₁ with an ethoxy ligand axially coordinated trans to the nitro­syl ligand. The Ru^II ion is equatorially coordinated by a tetramethylethylenediamine group acting as a bidentate ligand, and to two nitro moieties whose planes are tilted with respect to the mean equatorial plane. Each nitro­gen ligand bonded to the metallic centre has a different hybridization state.     

Synthesis and magnetic properties of copper (II)-lanthanoid (III) binuclear complexes with N,N′-bis(3-aminopropyl) oxamido ligand

Six novel μ-oxamido binuclear complexes, namely Cu(axpn)Ln(L)₂(ClO₄)₃ (Ln: Eu, Gd, Tb, Nd, Ho, Er), where oxpn is N,N'-bis(3-aminopropyl) oxamido, L denotes 5-nitro,10-phenanthroline (abbreviated as NO₂-phen), have been synthesized and characterised. The magnetic susceptibility of complexes Cu(oxpn)Gd(NO₂-phen)2(ClO₄)₃.2H₂O was measured over the 4–300 K and the observed data were successfully simulated by equation based on spin Hamiltonian operator (H = -2J₁ · S₂), giving the exchange integral J(Cu-Gd)=-1.62 cm^?1. This indicates a weak antiferromagnetic interaction between the Cu(II) and Gd(III) ions.     

Thermodynamic, crystallographic and solvent extraction properties of cobalt(II), nickel(II) and copper(II) complexes of ethylenediamine- N,N,N′,N′-tetraacetanilide

Complexes of ethylenediamine-N,N,N′,N′-tetraacetanilide (edtan, C₃₄H₃₆N₆O₁₄) with cobalt(II), nickel(II) and copper(II) in the solid state and in solution are reported for the first time. Thermodynamic data (stability constant, and derived Gibbs energy, enthalpy and entropy changes)for the 1 : 1 complexation of edtan with the metal ions at 298.15 K in water-saturated butan-1-ol gave the selectivity sequence log₁₀K_s; Ni²⁺, 4.56±0.02; Cu²⁺, 4.41±0.01; Co²⁺, 4.18±0.04 as found from microcalorimetric titration studies. The entropies suggested that the structure of the 1 : 1 complex with copper(II) contains fewer chelate rings than those for nickel(II) and cobalt(II) (δ_cS⁰ : Cu-21.4, Co 5.7, Ni 3.9 J mol⁻¹K⁻¹). Solid complexes of the metal ions with edtan and perchlorate as the counter anion were prepared. For each, a complex with a 1 : 1 metal: edtan stoichiometry with non-coordinated perchlorate was isolated. The X-ray structure of [Cu(edtan)(H₂O)][ClO₄]₂·1.5H₂O (1) revealed a six-coordinate Cu centre with edtan acting as pentadentate ligand (2N, 3O) with the coordination sphere completed by an oxygen atom from water. In striking contrast to the Cu complex, the Co centre in [Co(edtan)(H₂O)][ClO₄]₂·H₂O·0.5C₂H₅OH (2) is seven-coordinate with hexadentate edtan (2N, 4O) and one coordinated water molecule. There is thus an excellent confirmation of the results obtained from the microcalometric study in that edtan forms four chelate rings to Cu but five to Co in the solid state. The ability of the ligand to extract metal ions from water to the water-saturated butan-1-ol phase was assessed from distribution data as a function of the aqueous phase hydrogen ion concentration and of the ligand concentration in the organic phase. The data showed that Cu²⁺ is selectively extracted over a wide range of aqeous phase hydrogen ion concentrations.     

Die Kristallstruktur von Bis(N,N-Diethyl-N′-benzoylselenoureato)cadmium(II)

The Crystal Structure of Bis(N,N-Diethyl-N′-benzoylselenoureato)cadmium(II) . Cd(C₁₂H₁₅N₂OSe)₂ exists in a dimeric oxygen bridged form and crystallized in the monoclinic space group P2₁/n. The cell parameters are a = 12.506(3), b = 11.563(2), c = 18.924(4) Å, β = 91.59(3)°, Z = 4. The structure was solved with Patterson and direct methods and was refined to a final R-value of 6.58%. Cadmium is coordinated by 3 oxygen and 2 selenium atoms and exhibits the unusual coordination number 5. The coordination polyhedron is a distorted trigonal bipyramid, to bipyramids are connected by a common edge. The Cd? Se bond lengths are 2.591(1) and 2.565(1) Å, the Cd? O bond lengths are 2.263(6), 2.272(5) und 2.438(5) Å.     

Die Kristallstruktur von Bis(N,N-Diethyl-N′-benzoylselenoureato)zink(II)

The Crystal Structure of Bis(N,N-Diethyl-N′-benzoylselenoureato)zinc(II) . Zn(C₁₂H₁₅N₂OSe)₂ crystallizes in the acentric orthorhombic space group Pca2₁. The cell parameters are a = 16.914(5), b = 13.492(4), c = 11.705(5) Å and Z = 4. The structure was solved with Patterson and direct methods and was refined to a final R-value of 7,05%. Zn^II is coordinated to two N,N-Diethyl-N′-benzoylselenoureato molecules, which are bidentately coordinated through their oxygen and selenium atoms to form a distorted tetrahedron. The Zn? Se bond lenghts are 2.394(3) and 2.369(4) Å, the Zn? O bond lengths are 1.971(11) and 1.974(12) Å.     

Die Kristallstruktur von Bis(N,N-diethyl-N′ -benzoylselenoureato)nickel(II)

The Crystal Structure of Bis(N,N-diethyl-N′ -benzoylselenoureato)nickel(II) Ni(C₁₂H₁₅N₂OSe)₂ crystallizes in the monoclinic space group P2₁/c. The cell parameters are a = 11.399(3), b = 16.016(4), c = 14.910(6) Å, β = 104.64(3)° and Z = 4. The structure was solved with Patterson and direct methods and was refined to a final R-value of 5.43%. Nickel is coordinated to two N,N-diethyl-N′ -benzoylselenourea molecules to form a bidentally coordinated chelate complex with cis arrangement of the donor atoms. Coordinaton around the nickel atom is planar while the chelate rings diverge from planarity. The ethyl groups of one diethylamino group are disordered. The Ni? Se bond lengths are 2.244(1) and 2.264(1) Å, the Ni? O bond lengths are 1.871(4) and 1.883(4) Å, respectively.     

New seven-coordinate thiourea and N,N,N′,N′-tetramethylthiourea complexes of molybdenum(II) and tungsten(II)

The compounds [MI₂(CO)₃(NCMe)₂] (M = Mo or W) react with one equivalent of thiourea (tu) in MeOH or N,N,N′,N′-tetramethylthiourea (tmtu) in CH₂Cl₂ at room temperature to initially afford the monoacetonitrile compounds [MI₂(CO)₃(NCMe)L] (L = tu or tmtu) which rapidly transform to the isolated iodide bridged dimers, [M(μ-I)I(CO)₃L]₂ with loss of acetonitrile. Reaction of [WI₂(CO)₃(NCMe)₂] with two equivalents of tu or tmtu gave the expected mononuclear seven-coordinate compounds [WI₂(CO)₃L₂]. However, reaction of [MoI₂(CO)₃(NCMe)₂] with two equivalents of tu or tmtu rapidly affords the iodide-bridged dimers [Mo(μ-I)I(CO)₂L₂]₂ with loss of carbon monoxide from [MoI₂(CO)₃L₂]. The low temperature (−70°C) ¹³C NMR spectrum of [Mo(μ-I)I(CO)₂ {SC(NMe₂)₂}₂]₂ suggests the complex is based on two capped octahedra with a carbonyl ligand capping each octahedral face.     

X‐ray and DFT‐calculated structures of bis[N‐(quinolin‐8‐yl)benzamidato‐κ2N,N′]copper(II)

The application of transition metal chelates as chemotherapeutic agents has the advantage that they can be used as a scaffold around which ligands with DNA recognition elements can be anchored. The facile substitution of these components allows for the DNA recognition and binding properties of the metal chelates to be tuned. Copper is a particularly interesting choice for the development of novel metallodrugs as it is an endogenous metal and is therefore less toxic than other transition metals. The title compound, [Cu(C₁₆H₁₁N₂O)₂], was synthesized by reacting N‐(quinolin‐8‐yl)benzamide and the metal in a 2:1 ratio. Ligand coordination required deprotonation of the amide N—H group and the isolated complex is therefore neutral. The metal ion adopts a flattened tetrahedral coordination geometry with the ligands in a pseudo‐trans configuration. The free rotation afforded by the formal single bond between the amide group and phenyl ring allows the phenyl rings to rotate out‐of‐plane, thus alleviating nonbonded repulsion between the phenyl rings and the quinolyl groups within the complex. Weak C—H…O interactions stabilize a dimer in the solid state. Density functional theory (DFT) simulations at the PBE/6‐311G(dp) level of theory show that the solid‐state structure (C1 symmetry) is 79.33 kJ mol⁻¹ higher in energy than the lowest energy gas‐phase structure (C2 symmetry). Natural bond orbital (NBO) analysis offers an explanation for the formation of the C—H…O interactions in electrostatic terms, but the stabilizing effect is insufficient to support the dimer in the gas phase.     

N,N′-Dimethylthiourea Complees of Zinc,Cadmium(II), and Mercury(II)

N,N′-Dimethylthioharnstoff-Komplexe des Zn, Cd^II und Hg^II Komplexe des N,N′-Dimethylthioharnstoffs (DMTU) mit Zn–, Cd^II-und Hg^II-Halogeniden des Typs M(DMTU)₂X₂ und [HgDMTUX₂]₂ (X ? Cl, Br, J) wurden dargestellt und IR-spektroskopisch (4000-60cm^?1) sowie durch Leitfähigkeitsmessungen untersucht. Die Molekulargewichte einiger dieser Komplet in Nitrobenzol werden angegeben. Die 1:2-Komplexe Zn(DMTU)₂X₂, Cd(DMTU)₂X₂ (X ? Cl, Br, J) und Hg(DMTU)₂J₂ sind tetraedrisch, während die Komplexe Hg(DMTU)₂X₂ (X ? Cl, Br) eine pseudooktaedrische Halogen-verbrückte Konfiguration zu haben scheinen. Die 1:1 Hg^II-Komplexe [HgDMTUX₂]₂ (X ? Cl, Br, J) haben im festen Zustand eine dimere tetraedrische Halogen-verbrückte Struktur. In allen diesen Komplexen ist N,N′-Dimethylthioharnstoff über den Schwefel am Metall gebunden.     

Studies on 1,2-Bis(O-Aminophenoxy)Ethane-N,N,N′,N′;-Tetraacetic Acid Chelates of the Tripositive Lanthanide Ions

The acid dissociation constants of 1,2-bis(cis-aminophenoxy)ethane-N,N,N′,N′;-tetraacetic acid (H₄BAPAT or H₄Z), and the stability constants of its chelates with tripositive rare-earth metal ions have been determined by the potentiometric titration and mercury indicator electrode methods at 15°, 25′ and 35°C and an ionic strength of 0.1 (KNO₃). The existence of a monohydrogen chelate species, LnHZ, and the normal chelate, LnZ^?, is illustrated. Enthalpy and entropy changes characterizing the formation of the normal chelates and the dissociation of the last two protons of chelating acid have been calculated at 25°C. These functions have been compared with corresponding values for related chelating agents.     

Highly Selective Salicylate Membrane Electrode Based on N,N＇- （Aminoethyl）ethylenediamide Bis（2-salicylideneimine） Binuclear Copper（Ⅱ） Complex as Neutral Carrier

A new ion selective electrode for salicylate based on N,N＇-（aminoethyl）ethylenediamide bis（2-salicylideneimine） binuclear copper（Ⅱ） complex [Cu（Ⅱ）2-AEBS] as an ionophore was developed. The electrode has a linear range from 1.0 × 10^-1 to 5.0 ×10^-7 mol·L^- 1 with a near-Nemstian slope of （ - 55 ±1 ） mV/decade and a detection limit of 2.0 × 10-7 mol·L^-1 in phosphorate buffer solution of pH 5.0 at 25 ℃. It shows good selectivity for Sal^- and displays anti-Hofmeister selectivity sequence： Sal^-〉SCN^-〉 ClO4^- 〉I^-〉 NO2^- 〉Br^-〉 NO3^- 〉Cl^-〉 SO3^2- 〉 SO4^2- The proposed sensor based on binuclear copper（Ⅱ）complex has a fast response time of 5-10 s and can be used for at least 2 months without any major deviation. The response mechanism is discussed in view of the alternating current （AC） impedance technique and the UV-vis spectroscopy technique. The effect of the electrode membrane compositions and the experimental conditions were studied. The electrode has been successfully used for the determination of salicylate ion in drug pharmaceutical preparations.