Syntheses and structures of cobalt(II), nickel(II), and copper(II) complexes with N,N,N′,N′-tetraalkylpyridine-2,6-dicarboxamides (O-daap) containing nitrate as the counter ion

Reactions of M(NO₃)₂?·?xH₂O [M?=?Co(II), Ni(II), and Cu(II)] with N,N,N′,N′-tetraalkylpyridine-2,6-dicarboxamides(O-daap) in CH₃CN yield [Co(O-dmap)(NO₃)₂] (1), [Co(O-deap)(NO₃)₂] (2), [Co(O-dpap)(NO₃)₂] (3), [Ni(O-dmap)(H₂O)₃](NO₃)₂] (4), [Ni(O-deap)(H₂O)₂(NO₃)](NO₃)] (5), [Cu(O-deap)(NO₃)₂] (6), and [Cu(O-dpap)(NO₃)₂] (7). X-ray crystal structures of 1, 2, 4, 5, and 7 reveal that O-daap ligands coordinate tridentate to each metal, O–N–O, with nitrate playing a vital role in molecular and crystal structures of all the complexes. The coordination geometry in the two Co(II) complexes, 1 and 2, is approximately pentagonal bipyramidal with nitrate bonded in a slightly unsymmetrical bidentate chelating mode. [Ni(dmap)(H₂O)₃](NO₃)₂ (4) and [Ni(deap)(H₂O)₂(NO₃)](NO₃) (5) exhibit octahedral geometry, the former containing uncoordinated nitrate while the latter has one nitrate coordinated unidentate and the other nitrate outside the coordination sphere. The Cu(II) in [Cu(dpap)(NO₃)₂] (7) occupies a distorted square pyramidal geometry and is linked to two unidentate nitrates, although one nitrate is also involved in a weak interaction with the metal through its other oxygen. IR spectra and other physical studies are consistent with their crystal structural data. O-dmap?=?N,N,N′,N′-tetramethylpyridine-2,6-dicarboxamides; O-deap?=?N,N,N′,N′-tetraethylpyridine-2,6-dicarboxamides; and O-dpap?=?N,N,N′,N′-tetraisopropylpyridine-2,6-dicarboxamides.     

Kinetics of solvolysis of the trans-dichlorobis(R-ethylenediamine)cobalt(III) ion (R = N-methyl or N,N′-dimethyl) in urea–water mixtures

First order solvolysis rates of the trans-dichlorobis(R-ethylenediamine)cobalt(III) ion (R=N-Me or N,N-Me₂) complex have been investigated in mixtures formed by adding urea to H₂O, which enhances the dielectric constant and decreases solvent structure. Differential effects of the changes in solvent structure on the initial and transition states are found to be important factors controlling changes in the rate constant with solvent composition. The variation of the enthalpy and the entropy of activation with solvent composition are contrasted with their variations found for the solvolysis of the complexes in mixtures where solvent structure is enhanced by additions of a co-solvent to water. The application of a free energy cycle to the process of the initial state going to the transition state suggests that the cationic cobalt(III) complexes in the transition state are more stable than the cationic cobalt complexes the initial state in the water+urea mixtures.     

Studies on Am(III) separation from simulated high-level waste using cobalt bis(dicarbollide) (1? ) ion derivative covalently bound to N,N′-di-n-octyl diglycol diamide as extractant and DTPA as stripping agent

The separation of minor actinides from high level liquid waste (HLLW) belongs to the principal challenges in current nuclear treatment. A derivative based on two cobalt bis(dicarbollide) (1^?) ions covalently bound to the N,N??-di-n-octyl diglycolyl amide platform via diethyleneglycol chain with the formula {[(N,N??-(8-(OCH₂ CH₂)₂-1,2-C₂B₉H₁₀)(1??,2??-C₂B₉H₁₁)-3,3??-Co)(N,N??-n-C₈H₁₇)NCOCH₂]₂O}Na₂ (TODGA-COSAN), dissolved in low polar mixture of hexyl methyl ketone and n-dodecane, was used as an extractant for efficient Am(III)/Eu(III) separation from PUREX HLLW. Am(III) could be selectively stripped from loaded organic phase by using a stripping agent composed from 0.05?M DTPA and 1?M citric acid as a buffer and 1?M NaNO₃ at pH?3.0. Separation factor between europium and americium of 13 was achieved. The europium remaining in the organic phase could be consecutively effectively stripped by using solution of ammonium citrate or ammonium citrate with ammonium DTPA at pH~7.     

Kinetics and mechanism of the oxidation of [N-(2-hydroxy-ethyl)ethylenediamine-N,N′,N′-triacetatocobalt(II)] by vanadate ion

The kinetics of oxidation of Co^IIHEDTA {HEDTA = N-(2-hydroxyethyl)ethylenediamine-N,N,N-triacetic acid} by vanadate ion have been studied in aqueous acid in the pH range 0.75–5.4 at 43–57 °C. The reaction exhibits second-order kinetics; first-order in each of the reactants. The reaction rate is a maximum at pH = 2.1. A mechanism is proposed in which the species [Co^IIHEDTA(H₂O)]^– and VO₂ ⁺ react to form an intermediate which decompose slowly to give pentadentate Co^IIIHEDTA(H₂O) and V^IV as final products. The rate law was derived and the activation parameters calculated: H* = 26.96 kJ mol^–1 and S* = –311.08 JK^–1 mol^–1.     

N,N,N′,N′-tetrabutylsuccinylamide as a new extractant in n-dodecane for extraction of uranium(VI) and thorium(IV) ions

N,N,N,N-tetrabutylsuccinylamide (TBSA) was synthesized, characterised and used for the extraction of U(VI) and Th(IV) from nitric acid solutions into n-dodecane. Extraction distribution coefficients of U(VI) and Th(IV) as a function of aqueous nitric acid concentration, extractant concentration and temperature have been measured and found that n-dodecane as diluent was superior to 50% 1,2,4-trimethyl benzene (TMB) and 50% kerosene, (OK) system for extraction of U(VI) and Th(IV). The compositions of extracted species, equilibrium constants and enthalpies of extraction reactions have also been calculated. The formation of the 121 complex of uranyl(II) ion or the 141 complex of thorium(IV) ion, nitrate ion and TBSA and extracted species was further confirmed by the IR spectra of saturated extract of U(IV) and Th(IV).     

Gas phase ion molecule chemistry of tetracarbonyl (η5-cyclopentadienyl) vanadium by Fourier transform ion cyclotron resonance

The kinetics of the reactions between the CpV(CO)₄ molecule and its fragment cations and anions have been examined using Fourier transform ion cyclotron resonance (FTICR) techniques. With 25 eV electron impact ionization the fragment cations V⁺ and CpV(CO)_n=0–4⁺ react principally by charge exchange or by condensation with the parent neutral molecule. Rate constants for these pathways have been determined along with kinetic evidence for the existence of excited state cations. Some of the product cations show unexpected stability despite their large formal electron deficiency. Exchange of carbonyl ligands was also observed. Under 2.5 eV electron impact, only two anions are produced: CpV(CO)_n=2,3⁻, both of which are unreactive with the parent neutral.     

Molecular structure of potassium [N,N′-bis(salicylideneamino)nitroguanidonate-N,N′,-O,O′]nickel(ii), the product of condensation of (salicylideneamino)nitroguanidine with salicylaldehyde on a Ni2+ ion template

The crystal structure of the product of the condensation of (salicylideneamino)nitroguanidine with salicylaldehyde on a Ni²⁺ ion template, K[Ni(C₁₅H₁₀N₅O₄)] · DMF, has been studied. It was established that a planar Ni complex, consisting of isolated [NiL]^– anions and solvated [K⁺ · DMF] cations, is formed. The negative charge of the anion is localized mainly on the O atoms of the nitro group. The nitroguanidine fragment of the ligand occurs in the tautomeric form, which was not reported previously.Deceased in 1995Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2273–2277, September, 1996.     

Crescent aromatic oligothioamides as highly selective receptors for copper(Ⅱ) ion

A series of crescent aromatic oligothioamides(4, 6, 8, 15, and 18) bearing different number of sulfur atoms were designed and synthesized via thionation of their corresponding aromatic oligoamides(3, 5, and 7) using Lawesson's reagent. The X-ray structure of a trimeric analogue(13) revealed the presence of intramolecular three-center hydrogen bonds that are responsible for the rigidification of the molecular backbone. The extraction by these novel receptors toward some representative heavy metal cations(Zn2+, Cd2+, Co2+, Ni2+, Pb2+, and Cu2+) and alkali and alkaline earth metal cations(Li+, Na+, K+, Rb+, Cs+, Ca2+, and Sr2+) demonstrated high efficiency(83.5%–96.4%) and superior selectivity for Cu2+ over other selected metal cations. Particularly, the extractability was correlated to both the number of sulfur atoms and orientation of thiocarbonyl groups as revealed in the order: 6 4 18 15. This is in stark contrast to the oligoamides that only gave much lower extractability(5.9%–16.4%), suggestive of the importance of replacement of carbonyl oxygen atoms with sulfur atoms in the extraction of Cu2+. The complexation behavior of 4, 6, and 8 with Cu2+ was also examined by UV-Vis and NMR techniques.     

How large is the [Fe(III)(protoporphyrin IX)]+ ion (hemin+) in the gas phase?

Comparison of the collision cross-section of the [Fe(III)-protoporphyrin IX]+ ion, hemin+, measured by means of ion-mobility experiments and the cross-sections calculated from theoretical structures based on density functional theory reveals that hemin+, in the gas phase, contains intramolecular hydrogen bonding between its two propionic acid side-chains.     

N,N,N′,N′-tetrabutylmalonamide as a new extractant for extraction of nitric acid and uranium(VI) in toluene

N,N,N,N-tetrabutylmalonamide (TBMA) was synthesized and used for extraction of uranyl(II) ion from nitric acid media in toluene. The effects of nitric acid concentration, extractant concentration, temperature and salting-out agent (LiNO₃) on distribution coefficients of uranyl(II) ion have been studied. The extraction of nitric acid is also studied. The main adduct of TBMA and HNO₃ is HNO₃. TBMA in 1.0 mol/l nitric acid solution. The 1:2:3 complex of uranyl(II) ion, nitrate ion and TBMA as extracted species is further confirmed by IR spectra of the extraction of uranyl(II) ion with TBMA, and found that the NO ₃ ^– in the extraction species UO₂(NO₃)₂·3TBMA did not participate in coordination of uranyl(II) ion. The values of thermodynamic parameters have also been calculated.     

Binuclear iron(III)-iron(III) complexes with the tetradentate Schiff base N,N′-bis(salicylidene)ethylenediamine and dicarboxylic acids or dithiooxamide as bridging ligands

Summary Complexes of the type [(Fe(salen))₂L]·xH₂O (L = glutarate, adipate, pimelate or suberate dianion, x = 0 or L = dithio oxamidate dianion, x = 2) have been prepared and studied by elemental analyses, i.r. and electronic spectra, and magnetic measurements. A dimeric structure with an octahedral arrangement of Fe^III (S = 5/2) is proposed. Some of the complexes have been characterized by temperature-dependent magnetic susceptibilities, but an antiferromagnetic exchange interaction was found only for [(Fe(salen))₂dta]·2H₂O (H₂dta = dithio-oxamide).     

Supramolecular assemblies and modes of binding of the 1,6-hexanedipyridinium ion and the HCl salt of N,N′-bis(3-pyridylmethyl)-diaminoethane,with the symmetrically substituted tetramethylcucurbit[6]uril

The molecular binding behaviour of the symmetrically substituted tetramethylcucurbit[6]uril (TMeQ[6]) was examined in relationship to the two pyridine-based molecular guests 1,6-hexanedipyridinium dication (Hdipy²⁺) and the HCl salt of N,N′-bis(3-pyridylmethyl)-diaminoethane (Ediamp). The interactions and binding modes of each guest with TMeQ[6] are discussed using solution results (¹H NMR spectroscopy) and solid-state findings (single-crystal X-ray diffraction), to evaluate interactions in common. Supramolecular structures are formed that rely on a combination of the now typical driving forces associated with Q[n] as a molecular host, which are dipole–ion, hydrophobic, H-bonding and in the present examples include π…π and C–H…π interactions.     

Thermodynamics of the Extraction of U(VI) by N,N′-Didecanoylpiperazine

A novel extractant, N, N-didecanoylpiperazine (DDPEZ), was synthesized for the first time. The extraction of U(VI) by DDPEZ from aqueous nitric acid media in carbon tetrachloride has been studied. The dependence of extraction distribution ratio on concentration of aqueous nitric acid, extractant, salting-out agent and temperature was investigated and the enthalpy of the extraction was calculated.     

N,N′-Bis(trimethylsilyl)dicyandiamide

N,N-Bis(trimethylsilyl)dicyandiamide was prepared for the first time by the reaction of dicyandiamide with hexamethyldisilazane in boiling tetrahydrofuran. Thermal transformations of this compound were studied by DTA. The novel compound may be used in the synthesis of bis(trimethylsilyl)carbodiimide.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 498–500, March, 1994.     

Kristallstruktur von N,N,N′,N′-Tetraisopropyl-p-phenylen-diammonium-dichlorid und-bis(tetrachloroaluminat)

Summary Protonation of the sterically overcrowded N,N,N,N-tetraisopropyl-p-phenylenediamine leads to a significant shortening of the C-N bond lengths of 7 pm as well as to a widening of the phenyl ipso-angle to 122°. All structural changes can be attributed to the twisted diisopropylammonium substituents and their electron acceptor properties.

     

Structure of the Mo(CN)8 4− ion

Summary The question of the hybridization of the atomic orbitals of Mo in the Mo(CN)₈ ^4– ion is examined, and it is shown that the dodecahedral structure can exist without the participation off electrons.     

N,N′-Bis(silylmethyl)azodicarboxamides

Russian Journal of General Chemistry - The first representatives of silicon-containing azocarboxamides, N,N′-bis(silylmethyl) azodicarboxamides, were synthesized by the reaction of...     

Synthesis and Biological Evaluation of N,N′-di(thiopheneacetyl)diamines Series as Antitubercular Agents

The series of new N,N′-di(thiopheneacetyl)diamines derivatives, 8–17, were synthesized and evaluated for their in vitro antibacterial activity against Mycobacterium tuberculosis(TB), and the activity expressed as the minimum inhibitory concentration (MIC) in μ g/mL. Compound 13 was the only one determined to be active and exhibited a MIC 50 μg/mL, indicating that the alkyl chain-length of the diamines is critical for biological activity. This class of compound has not been evaluated before, and it could be a good starting point to find new lead compounds in the fight against multi-drug resistant TB.     

Kinetics and mechanism of the reduction of μ-adi-di[N,N′-bis{salicylideneethylenediaminatoiron(III)}] by dithionate ion

The kinetics and mechanism of the reduction of the μ-adi-di[N,N′-bis{salicylideneethylenediaminatoiron(III)}] complex, [Fe₂adi], by dithionate ion, S₂O₆ ^2?, have been investigated in aqueous perchloric acid at 29 °C, I = 0.05 mol dm^?3 (NaClO₄) and [H⁺] = 5.0 × 10^?3 mol dm^?3. Spectrophotometric titrations indicated that one mole of the reductant was oxidized per mole of oxidant. Kinetic profiles indicated first-order rate with respect to [Fe₂adi] but zeroth-order dependence on [S₂O₆ ^2?]. The rate of reaction increased with increase in [H⁺], decreased with increased dielectric constant, but was invariant to changes in ionic strength of the medium. Addition of small amounts of AcO^? and Mg²⁺ ions did not catalyse the reaction. A least-squares fit of rate against [H⁺]² was linear (r ² = 0.984) without intercept. The reaction was analysed on the basis of a proton-coupled outer-sphere electron transfer mechanism.     

Five coordinate complexes of N,N,N′,N′-tetraethylpyridine-2,6-dicarboxamide with copper Crystal and molecular structures of dichloro(N,N,N′,N′-tetraethylpyridine-2,6-dicarboxamido)copper(II) and chloro(perchlorato)(N,N,N′,N′-tetraethylpyridine-2,6-dicarboxamido)copper(II)

The title compound N,N,N′,N′-tetraethylpyridine-2,6-dicarboxamide (DEAP) forms a 1:1 complex with anhydrous CuCl₂, [Cu(DEAP)Cl₂], (1) which was crystallized from EtOH solution in the monoclinic space group P2_{1/ n} with cell constant, a = 10.024(1); b = 13.122(1); c = 14.404(1) Å β = 101.31(1)° V = 1857.8(3) ų and Z = 4. The chloro-perchlorato complex, [Cu(DEAP)Cl(ClO₄)], (2) obtained in near quantitative yield by reacting (1) with an excess of NaClO₄ in EtOH, crystallized in the monoclinic space group P2_{1/ n} with cell constants, a = 7.965(1); b = 25.827(2); c = 10.046(1) Å β = 98.81(1)° V = 2042.2(4) ų and Z = 4. Both (1) and (2) contain 5-coordinated copper linked to DEAP through O～N～O donor set of atoms with covalently bonded chlorine atoms in (1) and chlorine and perchlorate groups in (2). The coordination geometry is intermediate between square pyramidal and trigonal bipyramidal, and is probably best described as a trigonally distorted rectangular pyramid.