Mononuclear, oligonuclear and polynuclear metal coordination compounds with 1,2,4-triazole derivatives as ligands

Complexes of heterocyclic thione donors

The secular determinants obtained in the previous paper are solved for the energy levels which are important in the absorption spectra of the normal complex ions, leaving the crystalline field strength as a parameter. The values of B and C (Racah's parameters) there needed are determined from the observed spectra of free ions or in some cases by extrapolation. The f -values of the transitions which connect the energy levels calculated are estimated and compared with the observed intensities. The difference of the spectral width among absorption bands and lines is also considered using the energy diagram obtained. Following the assignments determined by the above considerations, the calculated positions of lines and bands are rather in good agreement with the experimental data in divalent ions [MX 6 ] 2+ (M=Cr, Mn, Fe, Co, Ni), when we adjust the crystalline field parameter D q suitably. In trivalent ions [MX 6 ] 3+ (M=Ti, V, Cr, Mn, Fe), it is necessary besides the adjustment of D q to use smaller values ...

On the absorption spectra of complex ions. II

Coordination compounds of copper, nickel and iron with Schiff bases derived from hydroxynaphthaldehydes and salicylaldehydes

At present, cisplatin (cis-diamminodichloroplatinum(II)) is one of the most largely employed anticancer drugs as it is effective in the treatment of 70-90% of testicular and, in combination with other drugs, of ovarian, small cell lung, bladder, brain, and breast tumors. Anyway, despite its high effectiveness, it exhibits some clinical problems related to its use in the curative therapy, such as a severe normal tissue toxicity (in particular, nephrotoxicity) and the frequent occurrence of initial and acquired resistance to the treatment. To obtain compounds with superior chemotherapeutic index in terms of increased bioavailability, higher cytotoxicity, and lower side effects than cisplatin, we report here on some gold(I) and gold(III) complexes with dithiocarbamate ligands (DMDT = N,N-dimethyldithiocarbamate; DMDTM = S-methyl-N,N-dimethyldithiocarbamate; ESDT = ethylsarcosinedithiocarbamate), which have been synthesized, purified, and characterized by means of elemental analyses, conductivity measurements, mono- and bidimensional NMR, FT-IR, and UV-vis spectroscopy, and thermal analyses. Moreover, the electrochemical properties of the designed compounds have been studied through cyclic voltammetry. All the synthesized gold complexes have been tested for their in vitro cytotoxic activity. Remarkably, most of them, in particular gold(III) derivatives of N,N-dimethyldithiocarbamate and ethylsarcosinedithiocarbamate, have been proved to be much more cytotoxic in vitro than cisplatin, with IC50 values about 1- to 4-fold lower than that of the reference drug, even toward human tumor cell lines intrinsically resistant to cisplatin itself. Moreover, they appeared to be much more cytotoxic also on the cisplatin-resistant cell lines, with activity levels comparable to those on the corresponding cisplatin-sensitive cell lines, ruling out the occurrence of cross-resistance phenomena and supporting the hypothesis of a different antitumor activity mechanism of action.

Gold dithiocarbamate derivatives as potential antineoplastic agents: design, spectroscopic properties, and in vitro antitumor activity.

Density (p), kinematic viscosity (), and absolute viscosity (η) are presented for mixtures of ethane-1,2-diol and N,N-dimethylformamide form -10 to +80 o C. The above properties were fitted by empirical equations stating their dependence on temperature and mole fraction of the mixture. Furthermore, some considerations regarding the meaning of the obtained adjustment parameters are made. The excess functions, such as molar volumes V E , have been derived

The N,N-dimethylformamide/ethane-1,2-diol solvent system. Density, viscosity, and excess molar volume at various temperatures

The complexes of deprotonated thiazolidine-2-thione (ttz) with many transition metals have been prepared. Probable structures have been proposed for the complexes on the basis of chemical analysis,...

Tautomeric equilibrium study of thiazolidine-2-thione. Transition metal complexes of the deprotonated ligand

Synthetic and characterization studies of manganese(11) complexes with tetrahydro-l,4-thiazin-3-one (tht) and thiazolidine-2-thione (ttz) are reported. The methods used for the characterization of the compounds include elementary analyses, molar conductances, magnetic moments and electronic and infrared spectroscopy. Assignments for the metal-ligand modes have also been made; the tht derivatives are coordinated through the oxygen atom, while the ttz derivatives are nitrogen-bonded in all the complexes. By use of infrared spectroscopy it has been possible distinguish whether or not the polyanions present in these derivatives are coordinated to the metal ion or are present as free ions.The wavelengths of the principal absorption peaks have been accounted for quantitatively in terms of the crystal field theory. The values of B and C obtained are significantly lower than the corresponding value for the free gaseous ion.

Carlo Preti

Papers

The N,N-dimethylformamide/ethane-1,2-diol solvent system. Density, viscosity, and excess molar volume at various temperatures

Tautomeric equilibrium study of thiazolidine-2-thione. Transition metal complexes of the deprotonated ligand

Coordination compounds of manganese(II) with Tetrahydro-1,4-thiazin-3-one and Thiazolidine-2-thione

The syntheses and properties of cobalt(II), nickel(II) and copper(II) complexes with some heterocyclic dithiocarbamates

Coordinating ability of methylpiperidine dithiocarbamates towards platinum group metals