Dinitrate Complex Research Articles

Generation, Characterization and Reactivity of a High-Valent Mononuclear Cobalt(IV)-Diazide Complex.

High-valent Fe(IV)=O intermediates of metalloenzymes have inspired numerous efforts to generate synthetic analogs to mimic and understand their substrate oxidation reactivities. However, high-valent M(IV) complexes of late transition metals are rare. We have recently reported a novel Co(IV)-dinitrate complex (1-NO3) that activates sp3 C-H bonds up to 87 kcal/mol. In this work, we have shown that the nitrate ligands in 1-NO3 can be replaced by azide, a more basic coordinating base, resulting in the formation of a more potent Co(IV)-diazide species (1-N3) that reacts with substrates (hydrocarbons and phenols) at faster rate constants and activates stronger C-H bonds than the parent complex 1-NO3. We have characterized 1-N3 employing a combination of spectroscopic and computational approaches. Our results clearly show that the coordination of azide leads to the modulation of the Co(IV) electronic structure and the Co(IV/III) redox potential. Together with the higher basicity of azide, these thermodynamic parameters contribute to the higher driving forces of 1-N3 than 1-NO3 for C-H bond activation. Our discoveries are thus insightful for designing more reactive bio-inspired high-valent late transition metal complexes for activating inert aliphatic hydrocarbons.

Assembly of Sn(IV)-Porphyrin Cation Exhibiting Supramolecular Interactions of Anion···Anion and Anion···π Systems

Trans-diaqua[meso-tetrakis(4-pyridyl)porphyrinato]Sn(IV) dinitrate complexes were assembled in a two-dimensional manner via hydrogen bonding between aqua ligands and pyridyl substituents. Interestingly, this supramolecular assembly was accompanied by unconventional noncovalent interactions, such as anion···anion and anion···π interactions, which were confirmed by X-ray crystallographic analysis. Two nitrate anions close to 2.070 Å were constrained in a confined space surrounded by four hydrogen-bonded Sn(IV)-porphyrin cations. The nitrate anion was also 3.433 Å away from the adjacent pyrrole ring, and the dihedral angle between the two mean planes was estimated to be 7.39°. The preference of the anion···π interaction was related to the electron-deficient π-system owing to the high-valent Sn(IV) center and cationic nature of the porphyrin complex. These two unconventional noncovalent interactions played an important role in the formation of a one-dimensional array with pairs of Sn(IV)-porphyrin cation and nitrate anion.

Crystal Structure and Hirshfeld Surface Analysis of Bis(Triethanolamine)Nickel(II) Dinitrate Complex and a Revelation of Its Characteristics via Spectroscopic, Electrochemical and DFT Studies Towards a Promising Precursor for Metal Oxides Synthesis

Metal complexes with chelating ligands are known as promising precursors for the synthesis of targeted metal oxides via thermal decomposition pathways. Triethanolamine (TEA) is a versatile ligand possessing a variety of coordination modes to metal ions. Understanding the crystal structure is beneficial for the rational design of the metal complex precursors. Herein, a bis(triethanolamine)nickel (II) dinitrate (named as Ni-TEA) crystal was synthesized and thoroughly investigated. X-ray crystallography revealed that Ni(II) ions adopt a distorted octahedral geometry surrounded by two neutral TEA ligands via two N and four O coordinates. Hirshfeld surface analysis indicated the major contribution of the intermolecular hydrogen-bonding between —OH groups of TEA in the crystal packing. Moreover, several O–H stretching peaks in Fourier transformed infrared spectroscopy (FTIR) spectra emphasizes the various chemical environments of —OH groups due to the formation of the hydrogen-bonding framework. The Density-functional theory (DFT) calculation revealed the electronic properties of the crystal. Furthermore, the Ni-TEA complex is presumably useful for metal oxide synthesis via thermal decomposition at a moderate temperature (380 °C). Cyclic voltammetry indicated the possible oxidative reaction of the Ni-TEA complex at a lower potential than nickel(II) nitrate and TEA ligand, highlighting its promising utility for the synthesis of mixed valence oxides such as spinel structures.

Magnesium hexakis(methanol)-dinitrate complex electrolyte for use in rechargeable magnesium batteries

Functional compatible electrolyte with Mg2+ intercalation cathodes represents one of the largest obstacles in the development of practical Mg batteries MBs. In current work, we report for the first time magnesium hexakis(methanol)-dinitrate complex (MHMD) electrolyte product reaction of 2,2-dimethoxypropane with magnesium nitrate hexahydrate via ‘Solvent-in-Salt’ method. 2,2-Dimethoxypropane as a water scavenger can capture reducible molecules like H2O and dehydrate Mg(NO3)2.6H2O to form magnesium hexakis(methanol)-dinitrate complex. Meanwhile, Mg cloud bonds will become weak—something which frees up the mobility of Mg2+. This electrolyte exhibits high ionic conductivity with low activation energy ~ 0.18 eV. The general aim of the investigation was to demonstrate a potential application of MHMD electrolyte in Mg-ion cell. Mg cells were analyzed with the use of cyclic voltammetry (CV), galvanostatic charging/discharging tests, and electrochemical impedance spectroscopy. A comparative study between different cathodes like V2O5, GeO2, TiO2, and S using MHMD electrolyte was performed. The S cathode has an initial discharge capacity of 370 mAh g−1 and retained a reversible capacity at 60 mAh g−1 after 20 cycles exhibiting better electrochemical performances than those of V2O5, GeO2, and TiO2 cathodes. This work opens up a new pathway to explore new electrolytic materials for MBs with high performance.

Structural and spectral characteristics of neptunyl nitrates NpO2(NO3)nq (n = 1–3, q = +1, 0, −1) and the hydrated complexes NpO2(NO3)2(H2O)m (m = 1–4)

The equilibrium structures and spectral properties of neptunyl nitrate complexes NpO2(NO3)nq (n=1–3, q=+1, 0, −1) and hydrated dinitrate complexes NpO2(NO3)2(H2O)m (m=1–4) have been studied systematically by carrying out DFT calculations. It is found that the neptunyl ion tends to bind to the nitrate ion in a bidentate fashion, and the 6 coordinate dinitrate in the m=2 complex is dominant in these hydrated neptunyl dinitrate complexes. This conclusion is strengthen by the good agreement between the calculated structural parameters, IR spectra of NpO2(NO3)2(H2O)2 and the latest experimental data.

Structure and Vibrational Spectra of Uranyl Dinitrate Complexes with Water and DMSO

Structural models were designed and spectral characteristics were computed based on DFT calculations for uranyl dinitrate complexes with H2O and DMSO [UO2(NO3)2·2DMSO, UO2(NO3)2·2H2O·2DMSO, UO2(NO3)2·2H2O·4DMSO]. Vibrational IR and Raman spectra of UO2(NO3)2·2DMSO were interpreted using models for bidentate and monodentate coordination of nitrate ions to uranyl. Several spectral signatures that characterized DMSO complexation in the second coordination sphere were identified and had analytical significance.

Synthesis and crystal structure of nickel(II) dinitrate molecular complex with 3,5-lutidine

Complex [Ni(NO3)2(3,5-lutidine)3] (3,5-lutidine, 3,5-Lut-C7H9N) was synthesized, and its crystal structure was determined. Complex crystals are monoclinic: space group Cc, a = 14.445(1) A, b = 10.024(1) A, c = 17.607(1) A, β = 108.96(1)°, V = 2411(1) A3, ρcalcd = 2.389 g/cm3, Z = 4. The structure is built of discrete neutral complexes [Ni(3,5-Lut)3(NO3)2]. The coordination sphere of Ni2+ ions is a disordered octahedron, which consists of three crystallographically nonequivalent lutidine ligands (Ni-N, 2.059–2.124 A) and two oxygen ions of the two nitrate ions (Ni-O, 2.047–2.258 A).

Structural and Spectroscopic Characterization of Plutonyl(VI) Nitrate under Acidic Conditions

The plutonyl(VI) dinitrate complex [PuO(2)(NO(3))(2)(H(2)O)(2)]·H(2)O (1) has been structurally characterized by single-crystal X-ray diffraction and spectroscopically characterized by solid-state vis-NIR and Raman spectroscopies. Aqueous solution spectroscopic studies indicate only weak plutonyl(VI) nitrate complexation, with the mononitrate complex dominating and negligible dinitrate formation, even in concentrated nitric acid.

TRLFS study on the complexation of Cm(III) with nitrate in the temperature range from 5 to 200 °C

The formation of aqueous Cm(III) nitrate complexes is studied in the temperature range from 5 to 200 °C by time resolved laser fluorescence spectroscopy (TRLFS). The experiments are performed in a custom build high pressure and high temperature fluorescence cell. The complex formation is measured at nitrate concentrations ranging from 0.10 to 4.61 mol/kg H2O. The mono- and dinitrate complexes are quantified by peak deconvolution of the fluorescence spectra and the complexation constants are determined as a function of the temperature. The conditional equilibrium constants are extrapolated to zero ionic strength using the specific ion interaction theory (SIT) and the thermodynamic standard state data (ΔrH°m, ΔrS°m, ΔrG°m, ΔrC°p,m) are determined from the temperature dependence of the equilibrium constants at I=0. The equilibrium constants up to 75 °C are well described by the Van´t Hoff equation (ΔrH°m independent of T and ΔrC°p,m=0). Modelling of the data at higher temperatures requires an extended equation including a term for the heat capacity changes (ΔrC°p,m).

Topological Features of Both Electron Density and Electrostatic Potential in the Bis(thiosemicarbazide)zinc(II) Dinitrate Complex

The experimental electron density of the bis(thiosemicarbazide)zinc(II) dinitrate complex, [Zn(CH5N3S)2](NO3)2,was studied. The Hansen-Coppens multipole model was used to extract the electron density from high-resolution X-ray diffraction data collected at 100 K. Careful strategies were designed for the electron density refinements regarding the charge transfer between the anionic and the cationic parts of the complex. Particular attention was also paid to the treatment of the electron density of the zinc atom interacting with two thiosemicarbazide ligands in a tetrahedral coordination. Nevertheless, the filled 3d valence shell of Zn was found unperturbed, and only the 4s shell was engaged in the metal-ligand interaction. Topological properties of both electron density and electrostatic potential, including kinetic and potential energy densities, and atomic charges were reported to quantify a metal-ligand complex with particular Zn-S and Zn-N bonds and hydrogen-bonding features. Chemical activities were screened through the molecular surface on which the three-dimensional electrostatic potential function was projected. The experimental results were compared to those obtained from gas-phase quantum calculations, and a good agreement was reached between these two approaches. Finally, among other electrostatic potential critical points, the values at the maxima corresponding to the nuclear sites were used as indices of the hydrogen-bonding capacity of the thiosemicarbazide ligand.

A New Water-soluble and Acid-stable Dinuclear Organoiridium Dinitrate Complex

Abstract A new water-soluble and acid-stable dinuclear organoiridium(III) dinitrate complex [{Cp∗Ir(NO3)}2(μ-Cl)2] (1, Cp∗ = η5-C5Me5) was synthesized by the reaction of a water-insoluble organoiridium(III) complex [(Cp∗IrCl)2(μ-Cl)2] (2) with two equivalents of AgBF4 in aqueous nitric acid (1 M HNO3/H2O) at 23 °C for 12 h. The structure of 1 with two monodentate NO3− ligands is discussed in comparison with structure of a mononuclear organoiridium(III) complex with one monodentate and one bidentate NO3− ligands, [Cp∗Ir(NO3)2] (3).

Synthesis and X-Ray Structure of [N,N-Bis(3,5-dimethylpyrazol-1-ylmethyl)-1-hydroxy-2-aminoethane](3,5-dimethylpyrazole) copper(II) dinitrate

The tridentate ligand N,N-Bis(3,5-dimethylpyrazol-1-ylmethyl)-1-hydroxy-2-aminoethane (L) has been prepared in one step by condensation of two equivalents of 1-hydroxymethyl-3,5-dimethylpyrazole with one equivalent of 2-aminoethanol. This reaction is carried out under microwave irradiation (60 W) in the absence of solvent for 20 min [1]. Using this ligand L a new Cu(II) dinitrate complex has been prepared. The single-crystal X-ray structure of the title compound, [N,N-bis(3,5-dimethylpyrazol-1-ylmethyl)-1-hydroxy-2-aminoethane] (3,5-dimethylpyrazole)copper(II) dinitrate, revels that the copper (II) ion is coordinated to two pyrazole nitrogens, one tertiary amine nitrogen of the ligand L and 3,5-dimethylpyrazole, and in the apical position by an alcohol O atom.

Influence of water molecule coordination on the magnetic properties of polyamine copper dinitrate complexes

The magnetic properties of two biogenic polyamine copper complexes were investigated by dc magnetization and electron paramagnetic resonance (EPR) measurements. The variation in temperature of the low field magnetization reveals that the absence or presence of water molecules in the copper coordination sphere results, respectively, in the enhancement or suppression of antiferromagnetic interactions between Cu2+ ions. Analysis of the EPR spectra shows considerable temperature dependence of both the g values and EPR linewidths that persist in the paramagnetic regime for both complexes. Such variation of EPR parameters is attributed to the interplay of demagnetizing field effects, pertinent to the purely paramagnetic compound, and to the presence of short-range magnetic order that applies to the antiferromagnetic polyamine complex.

Physicochemical studies on uranium(VI) complexes of N ,N-dialkylamides

Uranyl dinitrate complexes UO 2 (NO 3 ) 2 .2L with two N,N-dialkylamides, viz. N,N-dihexyloctanamide (L 1 ) and N,N-dihexyldecanamide (L 2 ) have been synthesized. IR spectra reveal that the amide molecules are O-bonded to U and both the nitrate ions act as bidentate groups. Visible spectra indicate the formation of a monedeatate inner-sphere metal-amide complex. PMR spectra of the complexes indicate the pressace of restricted rotation around the C-N bond. The variable temperature PMR studies suggest a dynamic equilibrium beteen the coordinated and free amide melecules Thermal investigations reveal that decomposition proceeds in three TG stages with four exothermic DTA steps correspending to the release of two molecules of amides and two mitrato groups, finally leading to U 3 O 8 .

Electronic structure of polycrystalline polyamine copper dinitrate complexes investigated by photoacoustic and electron paramagnetic resonance spectroscopy

Photoacoustic and electron paramagnetic resonance (EPR) spectroscopies have been applied to resolve the electronic structure in powder polycrystalline samples of three biogenic polyamine copper complexes, spermine copper dinitrate, aqua norspermine copper dinitrate, and homospermine copper dinitrate. The fine structure of the intense absorption band in the photoacoustic spectra is assigned to the d–d transitions between the crystal field split levels of copper ions, that cannot be discriminated in the UV/vis solution absorption spectra. Combination with the EPR results allows one to probe the variation of the electronic properties and bonding interaction at the copper site, consistent with the structural data for the crystalline complexes and further supports the reliability of the photoacoustic method to resolve the d–d transition band. A dominant contribution of the in-plane ligand field due to equatorial nitrogen atoms is deduced for the complexes of polyamines with copper salts.

Dipyrimidine-copper(II) dinitrate complexes showing magnetic interactions.

Crystals of Cu(II)(NO(3))(2)(pm)(3) (1), and two crystalline forms of Cu(II)(NO(3))(2)(H(2)O)(2)(pm)(2), (2) and (3), showed ferromagnetic, antiferromagnetic and paramagnetic interactions at extremely low temperatures, respectively. Crystal structure analyses revealed that the complexes were catena-dinitrato[mu-pyrimidine-kappaN(1):kappaN(3)]-(pyrimidine-N(1))copper(II), [Cu(NO(3))(2)(pm)(2)](n), catena-diaquadinitrato[mu-pyrimidine-kappaN(1):kappaN(3)]copper(II), [Cu(NO(3))(2)(H(2)O)(2)(pm)](n), and diaquadinitratodipyrimidinecopper(II), Cu(NO(3))(2)(H(2)O)(2)(pm)(2) for (1), (2) and (3), respectively. In (1) the Cu atom is coordinated by the two nitrates and N atoms of the non-bridging pyrimidine and bridging pyrimidine to form a one-dimensional coordination polymer. The complex is a five-coordinated square pyramid and can be regarded as a pseudo-seven-coordinated complex, since other short non-bonding Cu.O contacts are observed. In the crystals of (2) the pyrimidine bridges the Cu atoms to form a one-dimensional coordination chain. On the other hand, complex (3) is not a coordination polymer. It is important to form a coordination polymer for the appearance of the magnetic interactions. Types of coordination of the bridging organic moieties should also play an important role in magnetic properties. Magnetic measurements of (1) and (2) show that they are good examples of uniform S = 1/2 ferro- and antiferromagnetic Heisenberg chains with exchange parameters 2J/kB = +1.8 and -36 K, respectively.

Plutonium(IV) mononitrate and dinitrate complex formation in acid solutions as a function of ionic strength

Titrations of Pu(IV) with HNO3 in a series of aqueous HClO4 solutions ranging in ionic strength from 2 to 19 molal were followed using visible and near-infrared absorption spectrophotometry. The Pu 5f-5f spectra in the visible and near IR range change with complex formation. At each ionic strength, a series of spectra were obtained by varying nitrate concentration. Each series was deconvoluted into spectra of Pu4+ (aq), Pu(NO3)3− and Pu(NO3)22+ complexes, and simultaneously their formation constants were determined. When corrected for the incomplete dissociation of nitric acid, the ionic strength dependence of each formation constant can be described by two parameters, β0 and Δe using the formulae of specific ion interaction theory.

Synthesis of polymer-supported triphenylphosphine oxide complexes of divalent copper and cobalt. A study on their reactivity with sulfur dioxide

Polymer-supported triphenylphosphine oxide dihalide and dinitrate complexes of copper(II) and cobalt(II), ML n X 2· xH 2O (L = polystyryl diphenylphosphine oxide; n =2–4; x = 0–7; X = Cl −, Br − and NO 3 −) have been synthesised and characterised. Their reactions with sulfur dioxide have been investigated in the solid state and in toluene slurries at room temperature. The absorption of SO 2 by these complexes and the free polymeric ligand was also studied by thermogravimetrical analysis (TGA) in the 230-30°C temperature range. All the copper and some cobalt complexes form SO 2 adducts on exposure to sulfur dioxide in the solid state at room temperature. When the complexes were exposed to SO 2 as toluene slurries, the initial stoichiometry of some complexes was found to be modified by the loss of one or two equivalents of neutral polymeric ligand. TGA studies show that SO 2 adducts can only be formed from initial complexes. For all nitrate complexes studied, at room temperature (solid state or toluene slurries) and high temperature, it was found that nitrate ions were displaced and replaced by sulfate groups. These reactions have been found to be dependent on the medium of the reaction, on the temperature and on the nature of metal, anionic and neutral ligand. Some air scale stable SO 2 adducts of accurate formulae could be isolated and their infrared spectra have been recorded. Sulfur dioxide desorption of some SO 2 adducts has also been studied by heating at 160°C and reduced pressure for 1 h.

1H NMR Spectroscopic Study of Paramagnetic Lanthanide(III) Texaphyrins. Effect of Axial Ligation

Paramagnetic Ce(III), Pr(m), Nd(III), Sm(III), Eu(III), Tb(III), Dy(III), Ho(III), Er(III), Tm(III), and Yb(III) texaphyrins were studied in solution using [sup 1]H NMR spectroscopic techniques. Key spectroscopic features for the dinitrate complexes LnTx(NO[sub 3])[sub 2] were assigned on the basis of 1D NOE, COSY, and ROESY experiments as well as line width and isotropic shift analysis. The observed isotropic shifts can be fit to theoretical models, assuming dipolar contributions are dominant for all but the imino protons. The resulting calculated values are consistent with highly rhombic magnetic susceptibility tensors for those paramagnetic lanthanide texaphyrins in which one of the molecular magnetic axes is roughly perpendicular to the macrocycle plane. For the dinitrate complexes, a change in the magnetic anisotropy was observed between the Ho(ITI) and Er(III) texaphyrin complexes, a phenomenon that is considered reflective of the changes in metal-centered axial ligation that occur as the lanthanide series is transversed. Conformation of phosphate coordination in the solid state came from a single crystal X-ray diffraction analysis of the bis(diphenyl phosphate) adduct of Dy(III) texaphyrin. The Dy(III) ion is seven-coordinate with five donor atoms being provided by the texaphyrin ligand and two by monodentate diphenyl phosphate ions. The Dy(III) ion is only 0.073more » A from the plane through the five nitrogen atoms of the macrocycle. 35 refs., 7 figs., 5 tabs.« less

Crystal and molecular structure of nitrato-1,4,10-trioxa-7,13-diazacyclopentadecanecopper(II) nitrate, C10H22N2O3·Cu(NO3)2

The copper(II) dinitrate complex of the title heteromacrocycle has been investigated by X-ray diffraction. The structure was solved by direct methods and refined by a full-matrix least-squares, givingR=0.0318 with 1778 unique reflections. The Cu(II) cation is coordinated inside the N(7), N(13)-folded macrocycle. The coordination sphere of Cu(II) is a distorted square pyramid with N(7), O(10), N(13) of the macrocycle and O(1a) of the nitrate anion atoms occupying the corners of the base of the pyramid and the O(1) macrocycle atom in the apical position. The other nitrate group was found in a remote position with respect to the Cu(II) cation.