Electron transfer and CO addition to polynitrido cobalt carbonyl clusters: Parallel pathways for conversion of the [Co10N2(CO)(19)](4-) anion to the novel [Co11N2(CO)(21)](3-) anion

The redox aptitude of the dinitrido anion [Co10N2(CO)19]4- has been tested from both chemical and electrochemical points of view, together with its reactivity toward CO that induces disproportionation. In any case, through a remarkable overlapping of intermediate steps, the new anion [Co11N2(CO)21]3- (4) is eventually obtained. A detailed study of the pathways to 4 allowed the identification of three labile intermediates by their characteristic IR spectra as well as their electrochemical and paramagnetic properties. The unprecedented structure of trianion 4 has been studied in details in two different crystalline salts

Competitive binding of amino-acids and nucleic acid constituents towards the nitrosyliron paramagnetic probe

The competitive binding of amino-acids and nucleic acid constituents with the FeI(NO)2 group has been studied. The Fermi contact interaction between the metal ion and the ligand nuclei has been investigated by means of isotopic substitution and computer simulation. Comparable binding powers have been shown by amino-acid and nucleic acids site, depending on pH. The availability of an ionized mercapto group in amino-acid side chains strongly modifies the co-ordination behaviour

Effectiveness and limits of magnetic resonance techniques in the identification of different coordination pathways of the Mn(II) in the presence of biomacromolecules

Magnetic resonance techniques yield important information on different coordination behaviour of Mn(II) in the presence of biomacromolecules. A preliminary study on model systems is necessary to have a deeper insight on dynamics and structural aspects. The EPR technique is not able to identify a binding interaction between Trp and manganous ion when the metal is bonded to the Imidazole. Proton shift NMR studies on the Mn(II)-5ATP-Imid complex evidenziate a ternary system formation and a stacking interaction between the imidazole-ring and the nucleotide purine-moiety. An EPR and NMR combined analysis on the Mn(II)-5ATP-Trp system points out a stacking interaction and the simultaneous presence of a covalent binding between the metal ion and the biomolecules. The role of the metal ion to favour this coordination is suggested

Competitive binding of amino-acids and nucleic acid constituents toward the nitrosyliron paramagnetic probe

The competitive binding of amino-acids and nucleic acid constituents with the FeI(NO)2 group has been studied. The Fermi contact interaction between the metal ion and the ligand nuclei has been investigated by means of isotopic substitution and computer simulation. Comparable binding powers have been shown by amino-acid and nucleic acids site, depending on pH. The availability of an ionized mercapto group in amino-acid side chains strongly modifies the co-ordination behaviour

Electron spin relaxation and frequency dependent lineshape analysis of the 5'-ATP-Mn(II)-Trp system

A frequency-dependent lineshape analysis of the ESR spectra of ternary systems in solution has been carried out. The 5′-ATP—Mn(II)—Trp complex has been chosen as a model system. The analysis points out the presence of inverted spectra at both X- and Q-bands. The lineshape is described by a distribution of configurational sites, Yl(ω) = ΣkPkYk(H). The temperature dependence of the ESR linewidth has also been investigated and is discussed in terms of chemical equilibria and correlation times