Advances in the coordination chemistry of nitrogen ligand complexes of coinage metals

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.

A phosphorescent copper(i) coordination polymer with sodium 3,5-dimethyl-4-sulfonate pyrazolate

A phosphorescent copper(i) coordination polymer has been synthesized and characterized via ab initio PXRD.

β-Diketiminate complexes of the first row transition metals: applications in catalysis

Although β-diketiminate complexes have been widely explored in stoichiometric studies, their use as catalysts is largely underdeveloped.

Structure and photoluminescence of silver(i) trinuclear halopyrazolato complexes

Five halogen substituted pyrazolates, 4-chloro-3,5-diisopropylpyrazole (4-Cl-3,5-iPr2pzH), 4-bromo-3,5-diisopropylpyrazole (4-Br-3,5-iPr2pzH), 4-iodo-3,5-diisopropylpyrazole (4-I-3,5-iPr2pzH), 4-chloro-3,5-diphenylpyrazole (4-Cl-3,5-Ph2pzH), and 4-bromo-3,5-diphenylpyrazole (4-Br-3,5-Ph2pzH), were conveniently prepared by halogenation of the appropriate pyrazoles with N-halosuccinimides (NXS) (X = Cl, Br, and I) followed by complexation of the pyrazolate anions with silver(i) nitrate. Single crystal X-ray analysis revealed either dimeric trinuclear {[Ag(μ-4-X-3,5-R2pz)]3}2 (R = iPr, X = Cl, Br, and I) or trinuclear [Ag(μ-4-X 3,5-R2pz)]3 (R = iPr, X = I; R = Ph, X = Cl, R = Ph, X = Br) structures, the latter held together with argentophilic interactions (AgAg interactions) that could also be observed in the Raman spectra. The electronegativity of the halogen substituent could be correlated with the strength of the AgAg interaction and the wavelength of solid-state photoluminescence. All complexes were emissive on UV irradiation at low temperatures, with the colour of emission from the diisopropyl substituted analogues red shifted by the halogens in the order Cl (red) > Br (orange) > I (yellow). Emission from the diphenyl substituted analogues was dominated by the extended aromatic system and was largely invariant to the halogens.

New 15-membered tetraaza (N4) macrocyclic ligand and its transition metal complexes: spectral, magnetic, thermal and anticancer activity

Novel tetraamidemacrocyclic 15-membered ligand [L] i.e. naphthyl-dibenzo[1,5,9,12]tetraazacyclopentadecine-6,10,11,15-tetraoneand its transition metal complexes with Fe(II), Co(II), Ni(II), Cu(II), Ru(III) and Pd(II) have been synthesized and characterized by elemental analysis, spectral, thermal as well as magnetic and molar conductivity measurements. On the basis of analytical, spectral (IR, MS, UV-Vis, (1)H NMR and EPR) and thermal studies distorted octahedral or square planar geometry has been proposed for the complexes. The antitumor activity of the synthesized ligand and some complexes against human breast cancer cell lines (MCF-7) and human hepatocarcinoma cell lines (HepG2) has been studied. The complexes (IC50=2.27-2.7, 8.33-31.1μg/mL, respectively) showed potent antitumor activity, towards the former cell lines comparable with their ligand (IC50=13, 26μg/mL, respectively). The results show that the activity of the ligand towards breast cancer cell line becomes more pronounced and significant when coordinated to the metal ion.

Reactivity of bis(organoamino)phosphanes with magnesium(ii) compounds

The reactivity of bis(organoamino)phosphanes with magnesium(ii) reagents is reported. The outcome of the reactions is influenced by a tautomeric H-shift in ligand backbones.

Vapochromic properties versus metal ion coordination of β-bispyrazolato–copper(ii) coordination polymers: a first-principles investigation

Vapochromic properties of Cu(ii) coordination polymers are explained on the basis of first principles calculations.

Coordination frameworks assembled from CuII ions and H2-1,3-bdpb ligands: X-ray and magneto structural investigations, and catalytic activity in the aerobic oxidation of tetralin

CFA-5, a novel MOF containing Cu(ii) ions and pyrazolate ligands, shows heterogeneous catalytic activity in the liquid-phase aerobic oxidation of tetralin.

Bis{μ4-N-[phen-yl(pyridin-2-yl-aza-nid-yl)meth-yl]pyridin-2-aminido}tetra-kis(tetra-hydro-furan)-tetra-lithium

The title complex, [Li4(C17H14N4)2(C4H8O)4], bears a novel tetra-dentate di-amido ligand. In the tetra-nuclear centrosymmetric complex mol-ecule, the metal atoms exhibit two kinds of coordination modes. The middle two Li(+) cations are coord-inated by four N (ligand) and one O (tetra-hydro-furan, THF) atoms, resulting in a distorted square-pyramidal geometry. The outer two Li(+) cations are in distorted tetra-hedral environments consisting of three N (ligand) and one O (THF) atoms. The Li-N bond lengths vary from 2.020 (7) to 2.441 (6)Å.

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.