Synthesis and characterization of a binuclear rhenium nitropyrazole complex [Re2O3Cl2(PPh3)2(C3H2N3O2)2]

Tuning the structure and solubility of nanojars by peripheral ligand substitution, leading to unprecedented liquid-liquid extraction of the carbonate ion from water into aliphatic solvents

Nanojars, a novel class of neutral anion-incarcerating agents of the general formula [Cu(II)(OH)(pz)]n (Cun; n = 27-31, pz = pyrazolate anion), efficiently sequester various oxoanions with large hydration energies from water. In this work, we explore whether substituents on the pyrazole ligand interfere with nanojar formation, and whether appropriate substituents could be employed to tune the solubility of nanojars in solvents of interest, such as long-chain aliphatic hydrocarbons (solvent of choice for large-scale liquid-liquid extraction processes) and water. To this end, we conducted a comprehensive study using 40 different pyrazole ligands, with one, two or three substituents in their 3-, 4- and 5-positions. The corresponding nanojars are characterized by single-crystal X-ray diffraction and/or electrospray-ionization mass spectrometry (ESI-MS). The results show that Cun-nanojars with various substituents in the pyrazole 4-position, including long chains, phenyl and CF3 groups, can be obtained. Straight chains are also tolerated at the pyrazole 3-position, and favor the Cu30-nanojar. Homoleptic nanojars, however, could not be obtained with phenyl or CF3 groups. Nevertheless, if used in mixture with the parent non-substituted pyrazole, sterically hindered pyrazoles do form heteroleptic nanojars. With 3,5-disubstituted pyrazoles, only heteroleptic nanojars are accessible. The crystal structure of novel nanojars (Bu4N)2[CO3⊂{Cu30(OH)30(3,5-Me2pz)y(pz)30-y}] (y = 14 and 15) is presented. We find that in contrast to the parent nanojar, which is insoluble in aliphatic solvents and water, nanojars with alkyl substituents are soluble in saturated hydrocarbon solvents, whereas nanojars based on novel pyrazoles, functionalized with oligoether chains, are readily soluble in water. Liquid-liquid extraction of carbonate from water under basic pH is presented for the first time.

A [Cu3(μ3-O)]-pyrazolate metallacycle with terminal nitrate ligands exhibiting point group symmetry 3

The trinuclear triangular cuprate anion of the title compound, tris-[bis-(tri-phenyl-phospho-ranyl-idene)ammonium] tris-(μ2-4-chloro-pyrazolato-κ(2) N:N')-μ3-oxido-tris-[(nitrato-κ(2) O,O')cuprate(II)] nitrate monohydrate, (C36H30P2N)[Cu3(C3H2ClN2)3(NO3)3O]NO3·H2O, has point group symmetry 3., with the μ3-O atom located on the threefold rotation axis. The distorted square-pyramidal coordination sphere of the Cu(II) atom is completed by two N atoms of trans-bridging pyrazolate groups and a chelating nitrate anion. The complex anion is slightly bent, with the nitrate and pyrazolate groups occupying positions above and below the Cu3 plane, respectively. In the crystal, weak O-H⋯O and C-H⋯O hydrogen bonds, as well as π-π inter-actions, are present.

3,5-Bis(2,4-dinitrophenyl)-4-nitro-1H-pyrazole acetone monosolvate

The title structure, C₁₅H₇N₇O₁₀·C₃H₆O, was prepared by penta­nitration of 3,5-diphenyl-1H-pyrazole. The proton attached to a pyrazole N atom forms a hydrogen bond with the O atom of the acetone solvent mol­ecule, owing to the NO₂ enhanced acidity of the proton. The NO₂ group on the phenyl C atom is twisted by 33.9 (2)° from coplanarity with the ring in order to avoid a short intra­molecular O⋯O contact with an O atom of an adjacent pyrazole-bonded NO₂ group.

A pyrazolate-supported Fe(3)(mu(3)-O) core: structural, spectroscopic, electrochemical, and magnetic study

A comparison is made between the structural, spectroscopic, electrochemical, and magnetic properties of pyrazolate versus carboxylate complexes [Fe3(mu3(mu3O)(mu-LL)6Cl3]2- containing the Fe3(mu3-O)-motif. While the Fe3(mu3-O)-cores are structurally indistinguishable in the two types of complexes, their magnetic properties deviate from the expected values as a result of a through-pyrazole contribution to the overall antiferromagnetic exchange with J1/hc = -80.1 cm(-1) and J2/hc = -72.4 cm(-1), or J1/hc = 70.6 cm(-1) and J2/hc = -80.8 cm(-1), (Hex = -J1(S1S2 + S2S3) - J2S1S3). The magnetic properties of the pyrazolate complexes are further tuned by an antisymmetric exchange interaction term.

Inhibitive properties and surface morphology of a group of heterocyclic diazoles as inhibitors for acidic iron corrosion

The heterocyclic diazoles 3-amino-1H-isoindole, indazole, imidazole, 4-bromoimidazole, 4-methylimidazole, pyrazole, 4-nitropyrazole, and 4-sulfopyrazole were investigated as corrosion inhibitors of iron in 1 M HCl using ac and dc techniques. The polarization curves showed a decrease in corrosion current for the inhibitor-containing solution. Impedance spectra demonstrate that the charge-transfer resistance in the presence of these inhibitors was greater than in inhibitor-free solution, except for 4-nitropyrazole. The resistance increased with inhibitor concentration and with immersion time. The structural and electronic parameters of these diazoles were calculated using computational methodologies. The elemental composition and the speciation of the treated surfaces were investigated via XPS measurements, and morphological changes were monitored by vertical scanning interferometery.