Metallonitrosyl fragment as electron acceptor: Intramolecular charge transfer, long range electronic coupling, and electrophilic reactivity in the trans-[NCRu(py)4(CN)Ru(py)4NO]3+ Ion
The new complex trans-[NCRu(py)4(CN)Ru(py)4NO] (PF6)3 (I) was synthesized. In acetonitrile solution, I shows an intense visible band (555 nm, ε = 5800 M-1 cm-1) and other absorptions below 350 nm, associated with dπ → π*py and πpy → π*py transitions. The visible band is presently assigned as a donor...
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todo:paper_00201669_v41_n7_p1930_Roncaroli2023-10-03T14:16:53Z Metallonitrosyl fragment as electron acceptor: Intramolecular charge transfer, long range electronic coupling, and electrophilic reactivity in the trans-[NCRu(py)4(CN)Ru(py)4NO]3+ Ion Roncaroli, F. Baraldo, L.M. Slep, L.D. Olabe, J.A. acetonitrile ion metal nitric oxide nitrite ruthenium derivative solvent aqueous solution article chemical reaction chromatophore complex formation electron electron spin resonance electronics energy equilibrium constant infrared spectroscopy irradiation light absorption model oxidation reduction potential pH reduction surface charge synthesis ultraviolet radiation The new complex trans-[NCRu(py)4(CN)Ru(py)4NO] (PF6)3 (I) was synthesized. In acetonitrile solution, I shows an intense visible band (555 nm, ε = 5800 M-1 cm-1) and other absorptions below 350 nm, associated with dπ → π*py and πpy → π*py transitions. The visible band is presently assigned as a donor-acceptor charge transfer (DACT) transition from the remote Ru(II) to the delocalized {RuII-NO+} moiety. Photoinduced release of NO is observed upon irradiation at the DACT band. Application of the Hush model reveals strong electronic coupling, with HDA = ∼2000 cm-1. The difference between the optical absorption energy and redox potentials for the donor and acceptor sites (RuIII,II, 1.40 V, and NO+/NO, 0.50 V, vs Ag/AgCl, 3 M KCl, respectively) (hν - ΔEred) is 1.33 eV, a large value which probably relates to the significant changes in distances and angles for the Ru-N-O moiety upon reduction. UV-vis absorptions, IR frequencies, and redox potentials are solvent-dependent. Controlled potential reduction (of NO+) and oxidation (of Ru(II) associated with the dicyano-chromophore) of I afford stable species, [NCRuII(py)4(CN)Ru(py)4NO]2+ (Ired) and [NCRuIII(py)4(CN)Ru(py)4NO]4+ (Iox), respectively, which are characterized by UV-vis and IR spectroscopies. Ired shows an EPR spectrum characteristic of {Ru(II)-NO•} complexes. Compound I is electrophilically reactive in aqueous solution above pH 5: values of the equilibrium constant for the reaction [NCRu(py)4(CN)Ru(py)4NO]3++ 2 OH- ⇄ [NCRu(py)4(CN)Ru(py)4NO2]+ + H2O, K = 3.2 ± 1.4 × 1015 M-2, and of the rate constant for the nucleophilic addition of OH-, k = 9.2 ± 0.2 × 103 M-1 s-1(25 °C, I = 1 M), are obtained, with ΔΗ‡ = 90.7 ± 3.8 kJ mol-1 and ΔS‡ = 135 ± 13 J K-1 mol-1. The oxidized complex, Iox, shows an enhanced electrophilic reactivity toward OH-. This addition reaction is followed by irreversible processes, which most probably lead to disproportionation of bound nitrite and other products. Fil:Roncaroli, F. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Baraldo, L.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Slep, L.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Olabe, J.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00201669_v41_n7_p1930_Roncaroli |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
acetonitrile ion metal nitric oxide nitrite ruthenium derivative solvent aqueous solution article chemical reaction chromatophore complex formation electron electron spin resonance electronics energy equilibrium constant infrared spectroscopy irradiation light absorption model oxidation reduction potential pH reduction surface charge synthesis ultraviolet radiation |
| spellingShingle |
acetonitrile ion metal nitric oxide nitrite ruthenium derivative solvent aqueous solution article chemical reaction chromatophore complex formation electron electron spin resonance electronics energy equilibrium constant infrared spectroscopy irradiation light absorption model oxidation reduction potential pH reduction surface charge synthesis ultraviolet radiation Roncaroli, F. Baraldo, L.M. Slep, L.D. Olabe, J.A. Metallonitrosyl fragment as electron acceptor: Intramolecular charge transfer, long range electronic coupling, and electrophilic reactivity in the trans-[NCRu(py)4(CN)Ru(py)4NO]3+ Ion |
| topic_facet |
acetonitrile ion metal nitric oxide nitrite ruthenium derivative solvent aqueous solution article chemical reaction chromatophore complex formation electron electron spin resonance electronics energy equilibrium constant infrared spectroscopy irradiation light absorption model oxidation reduction potential pH reduction surface charge synthesis ultraviolet radiation |
| description |
The new complex trans-[NCRu(py)4(CN)Ru(py)4NO] (PF6)3 (I) was synthesized. In acetonitrile solution, I shows an intense visible band (555 nm, ε = 5800 M-1 cm-1) and other absorptions below 350 nm, associated with dπ → π*py and πpy → π*py transitions. The visible band is presently assigned as a donor-acceptor charge transfer (DACT) transition from the remote Ru(II) to the delocalized {RuII-NO+} moiety. Photoinduced release of NO is observed upon irradiation at the DACT band. Application of the Hush model reveals strong electronic coupling, with HDA = ∼2000 cm-1. The difference between the optical absorption energy and redox potentials for the donor and acceptor sites (RuIII,II, 1.40 V, and NO+/NO, 0.50 V, vs Ag/AgCl, 3 M KCl, respectively) (hν - ΔEred) is 1.33 eV, a large value which probably relates to the significant changes in distances and angles for the Ru-N-O moiety upon reduction. UV-vis absorptions, IR frequencies, and redox potentials are solvent-dependent. Controlled potential reduction (of NO+) and oxidation (of Ru(II) associated with the dicyano-chromophore) of I afford stable species, [NCRuII(py)4(CN)Ru(py)4NO]2+ (Ired) and [NCRuIII(py)4(CN)Ru(py)4NO]4+ (Iox), respectively, which are characterized by UV-vis and IR spectroscopies. Ired shows an EPR spectrum characteristic of {Ru(II)-NO•} complexes. Compound I is electrophilically reactive in aqueous solution above pH 5: values of the equilibrium constant for the reaction [NCRu(py)4(CN)Ru(py)4NO]3++ 2 OH- ⇄ [NCRu(py)4(CN)Ru(py)4NO2]+ + H2O, K = 3.2 ± 1.4 × 1015 M-2, and of the rate constant for the nucleophilic addition of OH-, k = 9.2 ± 0.2 × 103 M-1 s-1(25 °C, I = 1 M), are obtained, with ΔΗ‡ = 90.7 ± 3.8 kJ mol-1 and ΔS‡ = 135 ± 13 J K-1 mol-1. The oxidized complex, Iox, shows an enhanced electrophilic reactivity toward OH-. This addition reaction is followed by irreversible processes, which most probably lead to disproportionation of bound nitrite and other products. |
| format |
JOUR |
| author |
Roncaroli, F. Baraldo, L.M. Slep, L.D. Olabe, J.A. |
| author_facet |
Roncaroli, F. Baraldo, L.M. Slep, L.D. Olabe, J.A. |
| author_sort |
Roncaroli, F. |
| title |
Metallonitrosyl fragment as electron acceptor: Intramolecular charge transfer, long range electronic coupling, and electrophilic reactivity in the trans-[NCRu(py)4(CN)Ru(py)4NO]3+ Ion |
| title_short |
Metallonitrosyl fragment as electron acceptor: Intramolecular charge transfer, long range electronic coupling, and electrophilic reactivity in the trans-[NCRu(py)4(CN)Ru(py)4NO]3+ Ion |
| title_full |
Metallonitrosyl fragment as electron acceptor: Intramolecular charge transfer, long range electronic coupling, and electrophilic reactivity in the trans-[NCRu(py)4(CN)Ru(py)4NO]3+ Ion |
| title_fullStr |
Metallonitrosyl fragment as electron acceptor: Intramolecular charge transfer, long range electronic coupling, and electrophilic reactivity in the trans-[NCRu(py)4(CN)Ru(py)4NO]3+ Ion |
| title_full_unstemmed |
Metallonitrosyl fragment as electron acceptor: Intramolecular charge transfer, long range electronic coupling, and electrophilic reactivity in the trans-[NCRu(py)4(CN)Ru(py)4NO]3+ Ion |
| title_sort |
metallonitrosyl fragment as electron acceptor: intramolecular charge transfer, long range electronic coupling, and electrophilic reactivity in the trans-[ncru(py)4(cn)ru(py)4no]3+ ion |
| url |
http://hdl.handle.net/20.500.12110/paper_00201669_v41_n7_p1930_Roncaroli |
| work_keys_str_mv |
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1782030372007051264 |