The Role of the Pyrazolate Ligand in Building Polynuclear Transition Metal Systems. In: Karlin KD, editor. Progress in Inorganic Chemistry. Hoboken: John Wiley & Sons, Inc.; 1997. pp. 151-238. [DOI: 10.1002/9780470166475.ch3]

The use of DOSY experiments to determine the solution structures of coinage metal pyrazolates: The case of {[3,5-(CF3 )2 Pz]Ag}3

A series of DOSY experiments have been carried out to determine the solution stoichiometry of silver(I) 3,5-bis (trifluoromethyl)pyrazolate species. This compound exists as a trimer in the solid state (n = 3) but in solutions of chlorinated solvents, the DOSY data suggest the presence of a mixture of solvent stabilized monomer (n = 1) and dimer (n = 2) in equilibrium. Different approximations have been used including the Stokes-Einstein and the Stokes-Einstein-Gierer-Wirtz equations. Some methodological problems are discussed.

Hexameric Silver(I) Pyrazolate: Synthesis, Structure, and Isomerization

The first binary hexameric silver(I) pyrazolate (Ag₆pz₆) has been prepared, and X-ray analysis demonstrated that it takes a rare figure-eight shape (pz^- = deprotonated tert-butyl 3,5-diphenyl-1H-pyrazole-4-carboxylate). The hexamer can be easily converted to its tetrameric isomer (Ag₄pz₄) by recrystallization from ether. On the basis of the ¹H NMR and mass spectrometry measurements, it is conjectured that the hexamer, after dissolving in CHCl₃, quickly achieves equilibrium with Ag₄pz₄ and Ag₃pz₃, with the equilibrium lying far to the side of smaller rings.

Coinage Metal Pyrazolates [(3,5-(CF3)2Pz)M]3 (M = Au, Ag, Cu) as Buckycatchers

The synthesis and characterization of supramolecular assemblies {C60[M3]4}∞ consisting of C60 and coinage metal pyrazolates [M3] (i.e., [(3,5-(CF3)2Pz)M]3, where Pz = pyrazolate and M = Au, Ag, and Cu) are reported. {C60[Cu3]4}∞, {C60[Ag3]4}∞ and {C60[Au3]4}∞ form isomorphous crystals. The [M3] moieties adopt a concave conformation to complement the convex C60 surface. They exist as dimers of trimers (i.e., hexanuclear [M3]2 units) that are held together by three close M···M metallophilic interactions at 3.1580(17), 3.2046(7), and 3.2631(7) Å for copper, silver, and gold systems, respectively. The [M3]2 moieties surround each C60 in a tetrahedral fashion, while each [M3]2 is sandwiched by two C60 molecules to form a supramolecular 3D assembly.

Effect of configuration of 2-vinyldiazocarbonyl compounds on their reactivity: experimental and computational study

Non-fluorinated vinyldiazo compounds with trans-configuration irrespective of the nature of 3-R(1)-substituent (R(1) = H, Me, TBSO) even under ambient conditions easily cyclize to produce pyrazoles, while cis-stereoisomers undergo similar ring closure only at elevated temperatures or decompose to produce vinyloxocarbene reaction products. The 3-CF3-substituted analogues with cis- or trans-configuration do not produce pyrazoles at all, but on heating furnish only vinylcarbene derived products. DFT calculations of theoretical energy barriers adequately explain the different experimental reactivity found for stereoisomeric vinyldiazocarbonyl compounds, and a new model for their interconversion through the corresponding pyrazoles has been suggested.

Synthesis, spectral characterization and biological evaluation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes with thiosemicarbazone ending by pyrazole and pyridyl rings

Here we present the synthesis of the new Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes with chelating ligand (Z)-(2-((1,3-diphenyl-1H-pyrazol-4-yl)methylene) hydrazinyl)(pyridin-2-ylamino)methanethiol. All the complexes were characterized by elemental analysis, IR, (1)H NMR, UV-vis, magnetic susceptibility measurements and EPR spectral studies. IR spectra of complexes showed that the ligand behaves as NN neutral bidentate, NSN mononegative tridentate and NSNN mononegative tetradentate. The electronic spectra and the magnetic measurements suggested the octahedral geometry for all complexes as well as the EPR confirmed the tetragonal distorted octahedral for Cu(II) complex. Cd(II) complex showed the highest inhibitory antioxidant activity either using ABTS method. The SOD-like activity exhibited those Cd(II) and Zn(II) complexes have strong antioxidative properties. We tested the synthesized compounds for antitumor activity and showed that the ability to kill liver (HePG2) and breast (MCF-7) cancer cells definitely.

Self-assembly of tri-pyrazolate linked cages with di-palladium coordination motifs

A series of novel tripyrazolate linked metallomacrocycles and cages possessing different shapes were constructed by dimetal-coordination motifs in aqueous solution.

Trigonal prismatic Cu(I) and Ag(I) pyrazolato nanocage hosts: encapsulation of S8 and hydrocarbon guests

Two neutral hexanuclear trigonal prismatic cage molecules have been synthesized by coupling two planar triangular M3pz3-panels, M = Cu(I) and Ag(I), in eclipsed geometry. The ~230 Å(3) cage volume can be either vacant or occupied by neutral guests. The crystal structures of the M6-cyclohexane and Ag6-S8 host-guest species have been determined.

Chloridotris(3,5-dimethyl-1H-pyrazole-κN)(formato-κO)copper(II)-dichlorido-bis(3,5-dimethyl-1H-pyrazole-κN)copper(II) (2/1)

The asymmetric unit of the title compound, [Cu(CHO(2))Cl(C(5)H(8)N(2))(3)](2)·[CuCl(2)(C(5)H(8)N(2))(2)] or 2[A]·[B], contains one A mol-ecule and one half-molecule of B, located on a centre of inversion. The Cu(II) environments in A and B are different. In A, the Cu(II) atom is coordinated by three N atoms from three 3,5-dimethyl-1H-pyrazole (L) ligands, one O atom from a formate ligand and a chloride anion in an axial position [Cu-Cl = 2.4275 (7) Å] in a distorted tetra-gonal-pyramidal geometry. The Cu(II) atom in B is coordinated by two N atoms from two L ligands and two chloride anions [Cu-Cl = 2.2524 (6) Å] in a distorted square-planar geometry. In the crystal, inter-molecular N-H⋯O hydrogen bonds link mol-ecules A into centrosymmetric dimers. Inter-molecular N-H⋯Cl hydrogen bonds further link these dimers with the B mol-ecules, forming chains propagating in [101].