Rosalba Pinna

Complexes of copper(II), nickel(II) and cobalt(II) with 2-fluoro,5-nitroaniline and 4-fluoro,2-nitroaniline

Abstract Preparation of new complexes of 2 - fluoro,5 - nitroaniline (2-F,5-NA) and 4 - fluoro,2 - nitroaniline (4-F,2-NA) of the type ML n X 2 · m H 2 O (where M = Cu(II), Ni(II), Co(II); L = 2-F,5-NA; 4-F,2-NA; n = 2,4,6; X = Cl − , Br − , SCN − , ClO 4 − ; m = 0–2) are described and their i.r., electronic spectra, and magnetic moments are reported. The ligands act always as monodentate O-bonded. The compounds are generally high spin, non electrolytes, and present square planar, tetrahedral and hexacoordinate structures.

Cobalt(II) and copper(II) complexes of 3-amino-5-methylisoxazole

SummaryCobalt(II) and copper(II) halide, nitrate, thiocyanate and perchlorate complexes of 3-amino-5-methylisoxazole (3-AMI) have been prepared and characterized by means of magnetic, spectroscopic and molar conductivity measurements. In Cu(3-AMI)2X2 compounds (X = Cl, Br, N02) the 3-AMI ligand is bridging and bidentate [N (ring), O(bonded)]. In the other derivatives it is monodentate [N(ring) bonded]. All cobalt(II) complexes have an octahedral stereochemistry, if the Co(3-AMI)2X2 derivatives (X = Cl, Br), which are tetrahedral, are excluded. Copper(II) complexes have generally a distorted square pyramidal stereochemistry in the solid state and in solution.

Complexes of cobalt(II), nickel(II) and copper(II) with 4-amino-3,5-dimethylisoxazole

SummaryComplexes of the type M(4-ADI)nX2 · mH2O (where 4-ADI = 4-amino-3,5-dimethylisoxazole; n = 1–4; X = Cl, Br, I, SCN, ClO4; m = 1–4) have been studied by i.r. and electronic spectroscopy, magnetic and conductivity measurements. The ligand behaves as a monodentate -NH2 bonded species in monomeric complexes, but as a bridging ligand-NH2 and -N(ring) bonded species in polymeric complexes. All the compounds have an octahedral stereochemistry, except Co(4-ADI)2X2 (X = Cl, Br, I) complexes, which are tetrahedral.

Spectroscopic and biological characterization of the palladium(II) and platinum(II) complexes with benzoxazole and 2-methylbenzoxazole

Abstract Complexes of the type ML 2 X 2 (where M = Pd(II), Pt(II); L = benzoxazole (BO), 2-methylbenzoxazole (MeBO); X = Cl, Br, I, NO 3 , SCN) have been prepared and characterized by spectroscopic methods and conductivity measurements. The two ligands act as monodentate; the benzoxazole behaves as N-bonded, the 2-methylbenzoxazole as O-bonded. The compounds are non electrolytes and generally trans -square planar with exception of cis -square planar Pt(BO) 2 X 2 (X = Cl, Br), Pt(MeBO) 2 Cl 2 and Pd(MeBO) 2 X 2 (X = Cl, Br, NO 3 ). The biological activity of some compounds was also investigated.

Spectrophotometric and potentiometric study on platinum(II) chelates of mercapto carboxylic acids

Abstract The coordination of Pt(II) with different mercapto and dimercapto compounds has been studied using both potentiometric titration at 25°C in KCl 0.1 M and UV–Vis spectroscopy. The slow complex formation kinetics has been followed spectrophotometrically for several days on samples with different ligand molar fractions ranging from 0.1 to 1, keeping the ligand and metal concentration below 8×10−4 M. For the potentiometric titration, the ligand concentrations were kept constant at 10−3 M, and the 0.25, 0.5, 0.75 and 1.00 metal/ligand ratios were titrated in the pH range 2.5–11 for each ligand. The solutions were kept in a thermostatted bath at 25°C for 2 days before titration. The stabilization of the absorbance values under these conditions after 2 days, and the back titration with hydrochloric acid 0.1 M, led us to conclude that the proper equilibrium complex formation is reached under these conditions. Using KCl 0.1 M as an ionic strength medium, the reported formation constants are referred to the complexation reaction starting from [PtCl4]2−. Some models are proposed on the basis of the estimated stoichiometries.

Synthesis, spectroscopic, and biological characterization of the palladium(II) oxalato complexes with heterocyclic ligands

Abstract Palladium(II) oxalato complexes with heterocyclic ligands have been prepared and characterized by spectroscopic and biological studies. The compounds are of the general formula Pd(ox)(L) n where ox = oxalato For n = 1, the ligand is isoxazole, 3,5-dimethylisoxazole, 2-methyl-benzoxazole, 2,5-dimethylbenzoxazole, and ethylenediamine, for n = 2, the ligand is N methylimidazole, N -ethylimidazole, N -propylimidazole, 3-amino, 5-methylisoxazole, and 5-amino 3,4 dimethylisoxazole. The Pd(ox)(L) 2 soluble in water are monomeric square-planar; the Pd(ox)(L) that are little soluble in water are dimeric square-planar with the ligand bridging bidentate except to the chelate ethylenediamine. All the compounds exhibit a certain inhibitorial effect with the exception of the Pd(ox)(en) derivative.

Platinum(IV) chloride complexes with heterocydic ligands

Platinum(IV) chloride complexes with heterocyclic ligands have been prepared and characterized by infrared and electronic spectra. The compounds are of general formula Pt(L)nCl4, where L = N-ethylimidazole, N-propylimidazole, isoxazole, 3,5-dimethylisoxazole, benzoxazole, 2-methylbenzoxazole, 2,5-dimethylbenzoxazole, ethylenediamine, n = 2, 4, and also Pt(enEt2)3Cl4 X 2H2O, where enEt2 = N,N-diethylethylenediamine. These complexes are hexacoordinate with cis or trans configuration. The antitumoral activity of some complexes in mice inoculated with leukemia L1210 is reported.

Metal ion uptake from aqueous solution by olive stones: A carbon-13 solid-state nuclear magnetic resonance and potentiometric study

The use of biomasses that result from the agriculture and food industries in removing heavy metals from wastewaters is attracting increasing interest. We present a joined potentiometric and cross polarization magic angle spinning (CP-MAS) carbon-13 (13C) nuclear magnetic resonance (NMR) study on the interaction of olive stones with copper(II), nickel(II), and cadmium(II). The potentiometric measurements allow both to distinguish two kind of basic sites in the olive stones and to postulate the coordination models for the three studied metals. The NMR spectral analysis allows the attribution of the different signals to the components of the olive stone matrix. A comparison of CP-MAS 13C NMR spectra of the samples after metal treatment suggests a specific complexation between metal ions and hydroxyl groups on guaiacyl and syringyl moieties.

Equilibrium study on Pd(II) chelates of mercapto carboxylic acids

Abstract The coordination of Pd(II) with a set of different mercapto and dimercapto compounds has been investigated by potentiometric titration at 25°C in KCl 0.1 M. The ligand concentration ranged from 10−4 M to 10−3 M, and for each ligand concentration the 0.25, 0.50, 0.75 and 1.00 Metal/Ligand ratios were examined in the 2.5–11 pH range. Using KCl 0.1 M as an ionic strength medium the reported formation constants are implicitly referred to the complexation reaction starting from [PdCl4]2− as is generally done for the aquo ion. On the bases of the estimated complexation stoichiometries some coordination models are proposed. The influence of -SH basicity, total charge of complexes and steric factors on the coordination properties of the various ligands is discussed.

Infrared studies of group IIB metal complexes with some imidazole derivatives

Abstract The complexes formed by zinc(II), cadmium(II) and mercury(II) halides and perchlorates with N-ethylimidazole and N-propylimidazole have been prepared and characterized by molecular conductance and i.r. spectral data down to 100 cm −1 . On the basis of the assignments of the metal—halogen and the metal—ligand vibrations, the stereochemistry of the compounds was inferred.