A combined experimental and theoretical study on a single, unsupported oxo-bridged Mn(iii ,iii ) dimer coordinated to two iminobenzosemiquinone π-radical anions
| Autor: | Prasenjit Sarkar, Amrit Sarmah, Prantick Shaw, Chandan Mukherjee, Ganesh Chandra Paul, Suvendu Maity |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Dalton Transactions. 50:8768-8775 |
| ISSN: | 1477-9234 1477-9226 |
| Popis: | Ligand H2LAP comprises a non-innocent 2-aminophenol unit and an innocent bis(pyridin-2-ylmethyl)amine unit. The ligand, upon reaction with an equivalent amount of Mn(ClO4)2·6H2O in the presence of Et3N under air in MeOH, provided a mono(oxo)-bridged dinuclear Mn2 complex ({[(LISQ)MnIII-O-MnIII(LISQ)][(ClO4)]2}; 1). X-ray crystal structure analysis of complex 1 revealed that in the dicationic unit, the physical oxidation state of each Mn ion was +III and the 2-aminophenol unit of ligand H2LAP was in its one-electron oxidized iminobenzosemiquinone form. 1H-NMR measurement of complex 1 confirmed that the complex acquired a diamagnetic ground state (St = 0). Thus, antiferromagnetic couplings among the paramagnetic centers were realized. The UV-Vis-NIR spectrum of complex 1 was consisted of ligand-to-metal charge-transfer transitions in the visible region, while ligand-to-metal and metal-to-ligand charge-transfer transitions were noticed in the near-infrared region due to the presence of iminobenzosemiquinone radical units. The cyclic voltammogram of the complex showed three one-electron oxidation waves and two one-electron reduction waves. While the first two oxidation processes were metal-based, the two successive reductions were ligand-centered. DFT-based theoretical studies confirmed the assignment. |
| Databáze: | OpenAIRE |
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