A combined experimental and theoretical study on a single, unsupported oxo-bridged Mn(iii,iii) dimer coordinated to two iminobenzosemiquinone π-radical anions

0543394 - ÚOCHB 2022 RIV GB eng J - Journal Article
Paul, G. C. - Sarkar, P. - Sarmah, Amrit - Shaw, P. - Maity, S. - Mukherjee, C.
A combined experimental and theoretical study on a single, unsupported oxo-bridged Mn(iii,iii) dimer coordinated to two iminobenzosemiquinone π-radical anions.
Dalton Transactions. Roč. 50, č. 25 (2021), s. 8768-8775. ISSN 1477-9226. E-ISSN 1477-9234
R&D Projects: GA ČR(CZ) GBP208/12/G016; GA ČR(CZ) GX19-27454X
Institutional support: RVO:61388963
Keywords : transition-metal-complexes * manganese(iii) complexes * dimanganese complexes
OECD category: Physical chemistry
Impact factor: 4.569, year: 2021
Method of publishing: Limited access
https://doi.org/10.1039/D1DT00489A

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.
Permanent Link: http://hdl.handle.net/11104/0320609