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Proton-ligand association constants of 1-benzoyl(1,2,4-triazol-3-yl)thiourea (BTTU) and its complex formation constants with some bivalent metal ions Ni(II), Co(II), Mn(II), Zn(II), and Cu(II), have been determined potentiometrically in 50% EtOH–H2O and 0.1 M NaNO3. The complexes formed in solution have a stoichiometry of 1:1 and 1:2 [M:L], where M represents the metal ion and L the BTTU ligand. The corresponding thermodynamic parameters are derived and discussed. The complexes are stabilized by enthalpy changes and the results suggest that complexation is an enthalpy-driven process. The effects of metal ion, ionic radius, electronegativity, and nature of ligand on the formation constants are discussed. The formation constants of the complexes with 3d transition metals follow the order Mn2+ < Co2+ < Ni2+ < Cu2+ > Zn2+. The metal complexes were synthesized and characterized by elemental analyses, conductance, IR,1H NMR, and magnetic measurements. The low magnetic moment of 0.11 BM for the Cu(II) complex is suggestive of dimerization through Cu–Cu interaction. The concentration distribution diagrams of the complexes were evaluated. The ligands and their metal complexes have been screenedin vitroagainst some bacteria and fungi. [ABSTRACT FROM AUTHOR]

[Pd(BHEP)Cl2] (BHEp = 1,4-bis(2-hydroxyethyl)piperazine) was synthesized and characterized. The palladium center has a typical square-planar geometry with a tetrahedral distortion. The alcohol groups of the ligand do not participate in binding to Pd(II). The DFT/B3LYP method was used for geometric optimization of the ligand and the complex using the Gaussian 09 program and compared with experimental results. The stoichiometry and stability constants of the complexes formed between [Pd(BHEP)(H2O)2]2+and some selected amino acids, peptides, and DNA constituents were investigated at 25 °C and 0.1 M ionic strength. The binuclear complex [(H2O)(BHEP)Pd(Bip)Pd(BHEP)(H2O)]4+was detected, where Bip = 4,4′-bipiperidine. Inosine, uracil, and thymine interact with the binuclear complex via substitution of both coordinated water molecules. The potentiometric results were complimented by spectroscopic measurements. The concentration distribution diagrams of the various species formed were evaluated. [ABSTRACT FROM AUTHOR]

The interaction of dimethyltin(IV) dichloride (DMT) with 1,4-piperazine (PIP) was investigated. The complex formation equilibria of the complexes formed in solution were investigated. The stoichiometry and stability constants of the complexes formed in solution phase were determined at different temperatures and in solutions of dioxane–water mixtures of different dielectric constants. The equilibrium constant for the displacement of piperazine coordinated to dimethyltin(IV) by inosine as a representative of DNA was calculated. (DMT)(PIP)·3H2O was synthesized and characterized by elemental analysis, spectral, and thermal techniques. The antitumor activity of the complex was screened. [ABSTRACT FROM PUBLISHER]