Mixed-valent {M3(�3-O)}-carboxylates (M = FeII/III, RuII/III) have been intensively studied as intriguing models in the field of electron transfer. We are proposing analogous triangular motifs with 4-nitropyrazolates (4-NO2-pz-) bridges, containing the same planar triangular Fe3(�3-O) motif, but with different extend of electronic and magnetic communication among the three metal centers. Complexes [Fe3(�3-O)(4-NO2-pz)6X3]2- with X- = Cl-(1  ), Br-(2  ), NCS-(3  ; Figure 1) and CN-(4  ), show a systematic anodic shift of their one-electron reversible reduction: E1/2 = -0.70, -0.55, -0.36 and +0.10 V, respectively. Chemical reduction of compounds 1   - 4  by Bu4NBH4 leads to the mixed-valent analogues 1red   - 4red  , correspondingly. Spectroscopic studies (electronic, vibrational, 57Fe-M�ssbauer, EPR) of the mixed-valent complexes, in situ or after isolation, indentified high-spin (1   - 3  , 1red  , 2red  ) and low-spin (4  , 3red  , 4red  ) systems, as well as charge-localization (1red  , 2red  ) and delocalization (3red  , 4red  ) in mixed-valent trimers.   Figure 1. Ball-and-stick diagram of 3  .

Tuning of charge localization/delocalization and spin-state in mixed-valent triangular {Fe<sub>3</sub>(�<sub>3</sub>-O)}-pyrazolates

247th National Meeting (2014)

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Tuning of charge localization/delocalization and spin-state in mixed-valent triangular {Fe3(�3-O)}-pyrazolates

Tuning of charge localization/delocalization and spin-state in mixed-valent triangular {Fe₃(�₃-O)}-pyrazolates