Effect of non-covalent self-dimerization on the spectroscopic and electrochemical properties of mixed Cu(i) complexes.

Autor:	Cáceres-Vásquez J; Laboratorio de Compuestos de Coordinación y Química Supramolecular, Facultad de Química y Biología, Universidad de Santiago de Chile Av. Libertador Bernardo O'Higgins 3363, Estación Central, Casilla 40, Correo 33 Santiago Chile juan.guerrero@usach.cl cristian.veraoy@usach.cl., Jara DH; Facultad de Ingenieria y Ciencias, Universidad Adolfo Ibáñez Av. Padre Hurtado 750 Viña del Mar Chile., Costamagna J; Laboratorio de Compuestos de Coordinación y Química Supramolecular, Facultad de Química y Biología, Universidad de Santiago de Chile Av. Libertador Bernardo O'Higgins 3363, Estación Central, Casilla 40, Correo 33 Santiago Chile juan.guerrero@usach.cl cristian.veraoy@usach.cl.; Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Libertador Bernardo O'Higgins 3363, Estación Central, Casilla 40, Correo 33 Santiago Chile., Martínez-Gómez F; Laboratorio de Compuestos de Coordinación y Química Supramolecular, Facultad de Química y Biología, Universidad de Santiago de Chile Av. Libertador Bernardo O'Higgins 3363, Estación Central, Casilla 40, Correo 33 Santiago Chile juan.guerrero@usach.cl cristian.veraoy@usach.cl.; Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Libertador Bernardo O'Higgins 3363, Estación Central, Casilla 40, Correo 33 Santiago Chile., Silva CP; Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Libertador Bernardo O'Higgins 3363, Estación Central, Casilla 40, Correo 33 Santiago Chile., Lemus L; Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Libertador Bernardo O'Higgins 3363, Estación Central, Casilla 40, Correo 33 Santiago Chile., Freire E; Gerencia de Investigación y Aplicaciones, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica Avenida Gral. Paz 1499, 1650, San Martín Buenos Aires Argentina baggio@tandar.cnea.gov.ar.; Escuela de Ciencia y Tecnología, Universidad Nacional de San Martín, Argentina and Gerencia de Investigación y Aplicaciones, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica Buenos Aires Argentina.; Member of CONICET Argentina., Baggio R; Gerencia de Investigación y Aplicaciones, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica Avenida Gral. Paz 1499, 1650, San Martín Buenos Aires Argentina baggio@tandar.cnea.gov.ar., Vera C; Laboratorio de Compuestos de Coordinación y Química Supramolecular, Facultad de Química y Biología, Universidad de Santiago de Chile Av. Libertador Bernardo O'Higgins 3363, Estación Central, Casilla 40, Correo 33 Santiago Chile juan.guerrero@usach.cl cristian.veraoy@usach.cl., Guerrero J; Laboratorio de Compuestos de Coordinación y Química Supramolecular, Facultad de Química y Biología, Universidad de Santiago de Chile Av. Libertador Bernardo O'Higgins 3363, Estación Central, Casilla 40, Correo 33 Santiago Chile juan.guerrero@usach.cl cristian.veraoy@usach.cl.
Jazyk:	angličtina
Zdroj:	RSC advances [RSC Adv] 2023 Jan 03; Vol. 13 (2), pp. 825-838. Date of Electronic Publication: 2023 Jan 03 (Print Publication: 2023).
DOI:	10.1039/d2ra05341a
Abstrakt:	A series of six new Cu(i) complexes with ([Cu( N -{4- R }pyridine-2-yl-methanimine)(PPh 3 )Br]) formulation, where R corresponds to a donor or acceptor p -substituent, have been synthesized and were used to study self-association effects on their structural and electrochemical properties. X-ray diffraction results showed that in all complexes the packing is organized from a dimer generated by supramolecular π stacking and hydrogen bonding. 1 H-NMR experiments at several concentrations showed that all complexes undergo a fast-self-association monomer-dimer equilibrium in solution, while changes in resonance frequency towards the high or low field in specific protons of the imine ligand allow establishing that dimers have similar structures to those found in the crystal. The thermodynamic parameters for this self-association process were calculated from dimerization constants determined by VT- 1 H-NMR experiments for several concentrations at different temperatures. The values for K D (4.0 to 70.0 M -1 range), Δ H (-1.4 to -2.6 kcal mol -1 range), Δ S (-0.2 to 2.1 cal mol -1 K -1 range), and Δ G 298 (-0.8 to -2.0 kcal mol -1 range) are of the same order and indicate that the self-dimerization process is enthalpically driven for all complexes. The electrochemical profile of the complexes shows two redox Cu(ii)/Cu(i) processes whose relative intensities are sensitive to concentration changes, indicating that both species are in chemical equilibrium, with the monomer and the dimer having different electrochemical characteristics. We associate this behaviour with the structural lability of the Cu(i) centre that allows the monomeric molecules to reorder conformationally to achieve a more adequate assembly in the non-covalent dimer. As expected, structural properties in the solid and in solution, as well as their electrochemical properties, are not correlated with the electronic parameters usually used to evaluate R substituent effects. This confirms that the properties of the Cu(i) complexes are usually more influenced by steric effects than by the inductive effects of substituents of the ligands. In fact, the results obtained showed the importance of non-covalent intermolecular interactions in the structuring of the coordination geometry around the Cu centre and in the coordinative stability to avoid dissociative equilibria. Competing Interests: There are no conflicts to declare. (This journal is © The Royal Society of Chemistry.)
Databáze:	MEDLINE
Externí odkaz:	Zobrazit plný text záznamu