Current Design of Mixed-Ligand Complexes of Magnesium(II): Synthesis, Crystal Structure, Thermal Properties and Biological Activity against <i>Mycolicibacterium Smegmatis</i> and <i>Bacillus Kochii</i>

The interaction of Mg2+ with 2-furoic acid (HFur) and oligopyridines, depending on the synthesis conditions, leads to the formation of mixed-ligand complexes [Mg(H2O)4(phen)]·2HFur·phen·H2O (1), [Mg(NO3)2(phen)2] (2) and [Mg3(Fur)6(bpy)2]·3CH3CN (3); these structures were determined with an SC X-ray analysis. According to the X-ray diffraction data, in complex 1, obtained in ambient conditions, the magnesium cation coordinated four water molecules and one phenanthroline fragment, while in complexes 2 and 3 (synthesized in an inert atmosphere), the ligand environment of the complexing agent was represented by neutral oligopyridine molecules and acid anions. The thermal behavior of 1 and 2 was studied using a simultaneous thermal analysis (STA). The in vitro biological activity of complexes 1–3 was studied in relation to the non-pathogenic Mycolicibacterium smegmatis and the virulent strain Mycobacterium tuberculosis H37Rv

Ytterbium and Europium Complexes of Redox-Active Ligands: Searching for Redox Isomerism

The reaction of (dpp-Bian)­Eu^II(dme)₂ (<b>3</b>) (dpp-Bian is dianion of 1,2-bis­[(2,6-diisopropylphenyl)­imino]­acenaphthene; dme is 1,2-dimethoxyethane) with 2,2′-bipyridine (bipy) in toluene proceeds with replacement of the coordinated solvent molecules with neutral bipy ligands and affords europium­(II) complex (dpp-Bian)­Eu^II(bipy)₂ (<b>9</b>). In contrast the reaction of related ytterbium complex (dpp-Bian)­Yb^II(dme)₂ (<b>4</b>) with bipy in dme proceeds with the electron transfer from the metal to bipy and results in (dpp-Bian)­Yb^III(bipy)­(bipy^–̇) (<b>10</b>) – ytterbium­(III) derivative containing both neutral and radical-anionic bipy ligands. Noteworthy, in both cases dianionic dpp-Bian ligands retain its reduction state. The ligand-centered redox-process occurs when complex <b>3</b> reacts with <i>N</i>,<i>N</i>′-bis­[2,4,6-trimethylphenyl]-1,4-diaza-1,3-butadiene (mes-dad). The reaction product (dpp-Bian)­Eu^II­(mes-dad)­(dme) (<b>11</b>) consists of two different redox-active ligands both in the radical-anionic state. The reduction of 3,6-di-<i>tert</i>-butyl-4-(3,6-di-<i>tert</i>-butyl-2-ethoxyphenoxy)-2-ethoxycyclohexa-2,5-dienone (the dimer of 2-ethoxy-3,6-di-<i>tert</i>-butylphenoxy radical) with (dpp-Bian)­Eu^II(dme)₂ (<b>3</b>) caused oxidation of the dpp-Bian ligand to radical-anion to afford (dpp-Bian)­(ArO)­Eu^II(dme) (ArO = OC₆H₂-3,6-<i>t</i>Bu₂-2-OEt) (<b>12</b>). The molecular structures of complexes <b>9</b>–<b>12</b> have been established by the single crystal X-ray analysis. The magnetic behavior of newly prepared compounds has been investigated by the SQUID technique in the range 2–310 K. The isotropic exchange model has been adopted to describe quantitatively the magnetic properties of the exchange-coupled europium­(II) complexes (<b>11</b> and <b>12</b>). The best-fit isotropic exchange parameters are in good agreement with their density functional theory-computed counterparts

&alpha;-Diimine Cisplatin Derivatives: Synthesis, Structure, Cyclic Voltammetry and Cytotoxicity

Three new Pt(II) complexes [(dpp-DAD)PtCl2] (I), [(Mes-DAD(Me)2)PtCl2] (II) and [(dpp-DAD(Me)2)PtCl2] (III) were synthesized by the direct reaction of [(CH3CN)2PtCl2] and corresponding redox-active 1,4-diaza-1,3-butadienes (DAD). The compounds were isolated in a single crystal form and their molecular structures were determined by X-ray diffraction. The purity of the complexes and their stability in solution was confirmed by NMR analysis. The Pt(II) ions in all compounds are in a square planar environment. The electrochemical reduction of complexes I&ndash;III proceeds in two successive cathodic stages. The first quasi-reversible reduction leads to the relatively stable monoanionic complexes; the second cathodic stage is irreversible. The coordination of 1,4-diaza-1,3-butadienes ligands with PtCl2 increases the reduction potential and the electron acceptor ability of the DAD ligands. The synthesized compounds were tested in relation to an adenocarcinoma of the ovary (SKOV3)