Properties of a dinuclear Mn(III, III) complex with a tri-phenolate ligand [N₄O₃]^3- and a new complex containing a ligand covalently linked to ruthenium tris-bipyridine

A new high valent complex [Mn₂(III, III)L(μ-OAc) ₂]·PF₆(2a) was prepared, where L was the trianion of 2, 6-bis {[(2-hydroxy-5-tert-butylbenzyl) (pyridyl-2-methyl)-amino]-methyl}- 4-methylphenol, which contains two additional phenolate groups and two tert-butyl groups compared to its parent [Mn₂(II, II) (bpmp) (μ-OAc)₂]·ClO₄ (1). These improvements narrowed the disparity between the new model and (Mn)₄ cluster (OEC in nature). Moreover, L was modified to be covalently linked with Ru(II) tris-bipyridine through an amide bond to construct a complex 2b for the study of photoinduced electron transfer (PET). UV-vis, IR, emission spectra and electrochemistry were used to investigate their photochemistry properties. The results showed that 2b has good photochemistry properties and the E _1/2 of Ru³⁺/Ru²⁺ was higher than those of phenol⁺/phenol and Mn (III, IV)/Mn (III, III). After coordination of manganese ions, the electron transfer process in the model complex conforms to the basic principles of electron donor side of photosystem II (PS II) in nature.