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Please use this identifier to cite or link to this item: https://hdl.handle.net/2445/164927
Kinetico-mechanistic studies on substitution reactions on cross-bridged cyclen CoIII complexes with nucleosides and nucleotides
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Kinetico-mechanistic studies on the substitution reactivity of the [Co{(μ-ET)cyclen}(H2O)2] 3+ complex cation at pH values within the 6.0-7.0 range with biologically significant ligands have been carried out. The substitution processes have been found to occur exclusively on the mono-hydroxobridged [(Co{(μ-ET)cyclen}(H2O))2(μ-OH)]5+ species formed after equilibration of the cobalt complex in the relevant medium. The studies conducted on the substitution of the aqua/hydroxo ligands of this dinuclear species are indicative of a dominant role of outer-sphere complexation, involving hydrogen-bonding interactions. The values of the outer-sphere complex formation equilibrium constant are in line with the intervention of both the exiting aqua ligands and the NH groups at the encapsulating {(μ-ET)cyclen} ligand. These complexes result in the preferential formation of O- or N-bonded nucleotides depending on the structure of the base moiety of the ligand. Even the entry of the different donor bonded nucleotides is hampered by the hydrogen-bonding interaction with the dangling moiety of an already coordinated ligand. In general the overall substitution processes occur at a faster rate than those published for the fully alkylated encapsulating {(Me)2(μ-ET)cyclen} ligand derivative, as expected for the still available base-catalysing NH groups in the {(μ-ET)cyclen} ligand.
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VÁZQUEZ VALERO, Marta, FONT BARDIA, Ma. Mercedes and MARTÍNEZ LÓPEZ, Manuel. Kinetico-mechanistic studies on substitution reactions on cross-bridged cyclen CoIII complexes with nucleosides and nucleotides. Dalton Transactions. 2015. Vol. 44, num. 42, pags. 18643-18655. ISSN 1477-9226. [consulted: 12 of August of 2026]. Available at: https://hdl.handle.net/2445/164927