Hydrogen atom transfer (HAT) reactions of metal–oxygen intermediates such as metal-oxo, -hydroxo and -superoxo species have so far been studied extensively. However, HAT reactions of metal-aqua complexes are yet to b...Hydrogen atom transfer (HAT) reactions of metal–oxygen intermediates such as metal-oxo, -hydroxo and -superoxo species have so far been studied extensively. However, HAT reactions of metal-aqua complexes are yet to be studied in comparison with those of the corresponding metal-hydroxo complexes. In this study, a series of Mn(Ⅲ)-aqua complexes, [(dpaq^(5R))Mn^(Ⅲ)(OH_(2))]^(2+) (dpaq^(5R) = 2-[bis(pyridin-2-ylmethyl)]amino-N-quinolin-8-yl-acetamidate with a substituent at the 5-position;R = NO_(2), Cl, H, Me and OMe) were synthesized by protonating the corresponding Mn(Ⅲ)-hydroxo complexes, [(dpaq^(5R))Mn^(Ⅲ)(OH)]^(+), with trifluoromethanesulfonic acid (HOTf). X-ray crystal structures of both [(dpaq^(5R))Mn^(Ⅲ)(OH)]^(+) and [(dpaq^(5R))Mn^(Ⅲ)(OH_(2))]^(2+) complexes showed a mononuclear Mn^(Ⅲ) center in a distorted octahedral environment. The electronic substitution effect of the dpaq ligand on the HAT reactions of [(dpaq^(5R))Mn^(Ⅲ)(OH)]^(+) and [(dpaq^(5R))Mn^(Ⅲ)(OH_(2))]^(2+) was then examined by determining the rate constants (k2) of the HAT reactions from 4-methoxy-2,6-di-tert-butylphenol to the Mn(Ⅲ)-hydroxo and -aqua complexes. Hammett plots indicate that HAT from 4-methoxy-2,6-di-tert-butylphenol to [(dpaq^(5R))Mn^(Ⅲ)(OH)]^(+) proceeds via an oxidative asynchronous coupled proton–electron transfer (CPET), whereas HAT from 4-methoxy-2,6-di-tert-butylphenol to [(dpaq^(5R))Mn^(Ⅲ)(OH_(2))]^(2+) proceeds mainly via a basic asynchronous CPET. The contribution of a stepwise electron transfer (ET)/proton transfer (PT) pathway is discussed by comparing the electronic substitution effect on the rate constants of outer-sphere electron transfer and HAT reactions. This study has provided valuable insights into the asynchronous CPET mechanisms of HAT reactions in which the oxidative vs. basic pathways are determined to exhibit reversed electronic substitution effects on HAT reactions of Mn(Ⅲ)-hydroxo and Mn(Ⅲ)-aqua complexes.展开更多
In the work [1] is shown the possibility of the use the phenomena of the electrical-induced selective drift of cationic aquacomplexes in the water solution of the salts for creating of the new, non-electrode, power-sa...In the work [1] is shown the possibility of the use the phenomena of the electrical-induced selective drift of cationic aquacomplexes in the water solution of the salts for creating of the new, non-electrode, power-saving technology of the solution enrichment by desired element. The development of the naturally-scientific basis of this technology has showed that inertial properties of formed in the solution over-molecular structural units—clusters depends from that’s dimensions. Dimensions of these clusters are in limits from scores of angstrom to fractions of micron, at the same time liquid mediums are the base of functioning both biological and technological systems. Thus, water solution of salt contains nanoparticles and biological and many technological systems are functioning with the assistance of nanoparticles. For example, the ordinary blood circulatory system or many of chemical processing. The casual or intentional action of aperiodic electric field on systems containing salts solutions produces some positive or negative effects. This work shows new approach for theoretical describing of salts solution in dielectric liquids and contains some data on the realized experiments.展开更多
基金supported by the NRF of Korea through CRI(NRF-2021R1A3B1076539 to W.N.)the Basic Science Research Program(NRF-2020R1I1A1A01074630 to Y.-M.L.and NRF-2019R1I1A1A01055822 to M.S.S.)+1 种基金supported by Grants-in-Aid(no.16H02268 to S.F.)from the Ministry of Education,Culture,Sports,Science and Technology(MEXT)Japan.
文摘Hydrogen atom transfer (HAT) reactions of metal–oxygen intermediates such as metal-oxo, -hydroxo and -superoxo species have so far been studied extensively. However, HAT reactions of metal-aqua complexes are yet to be studied in comparison with those of the corresponding metal-hydroxo complexes. In this study, a series of Mn(Ⅲ)-aqua complexes, [(dpaq^(5R))Mn^(Ⅲ)(OH_(2))]^(2+) (dpaq^(5R) = 2-[bis(pyridin-2-ylmethyl)]amino-N-quinolin-8-yl-acetamidate with a substituent at the 5-position;R = NO_(2), Cl, H, Me and OMe) were synthesized by protonating the corresponding Mn(Ⅲ)-hydroxo complexes, [(dpaq^(5R))Mn^(Ⅲ)(OH)]^(+), with trifluoromethanesulfonic acid (HOTf). X-ray crystal structures of both [(dpaq^(5R))Mn^(Ⅲ)(OH)]^(+) and [(dpaq^(5R))Mn^(Ⅲ)(OH_(2))]^(2+) complexes showed a mononuclear Mn^(Ⅲ) center in a distorted octahedral environment. The electronic substitution effect of the dpaq ligand on the HAT reactions of [(dpaq^(5R))Mn^(Ⅲ)(OH)]^(+) and [(dpaq^(5R))Mn^(Ⅲ)(OH_(2))]^(2+) was then examined by determining the rate constants (k2) of the HAT reactions from 4-methoxy-2,6-di-tert-butylphenol to the Mn(Ⅲ)-hydroxo and -aqua complexes. Hammett plots indicate that HAT from 4-methoxy-2,6-di-tert-butylphenol to [(dpaq^(5R))Mn^(Ⅲ)(OH)]^(+) proceeds via an oxidative asynchronous coupled proton–electron transfer (CPET), whereas HAT from 4-methoxy-2,6-di-tert-butylphenol to [(dpaq^(5R))Mn^(Ⅲ)(OH_(2))]^(2+) proceeds mainly via a basic asynchronous CPET. The contribution of a stepwise electron transfer (ET)/proton transfer (PT) pathway is discussed by comparing the electronic substitution effect on the rate constants of outer-sphere electron transfer and HAT reactions. This study has provided valuable insights into the asynchronous CPET mechanisms of HAT reactions in which the oxidative vs. basic pathways are determined to exhibit reversed electronic substitution effects on HAT reactions of Mn(Ⅲ)-hydroxo and Mn(Ⅲ)-aqua complexes.
文摘In the work [1] is shown the possibility of the use the phenomena of the electrical-induced selective drift of cationic aquacomplexes in the water solution of the salts for creating of the new, non-electrode, power-saving technology of the solution enrichment by desired element. The development of the naturally-scientific basis of this technology has showed that inertial properties of formed in the solution over-molecular structural units—clusters depends from that’s dimensions. Dimensions of these clusters are in limits from scores of angstrom to fractions of micron, at the same time liquid mediums are the base of functioning both biological and technological systems. Thus, water solution of salt contains nanoparticles and biological and many technological systems are functioning with the assistance of nanoparticles. For example, the ordinary blood circulatory system or many of chemical processing. The casual or intentional action of aperiodic electric field on systems containing salts solutions produces some positive or negative effects. This work shows new approach for theoretical describing of salts solution in dielectric liquids and contains some data on the realized experiments.
