In by admin

Name Miss Jessica Lopez
Organization or Institution Florida International University
Presentation Type Poster
Topic Inorganic Chemistry
Title

Synthesis and characterization of Pyrazolate-Supported Fe33-O) complexes and their redox properties

Author(s)

Jessica M. López Plá and Raphael G. Raptis

Author Institution(s)

Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199

Abstract

Trinuclear complexes with formula [Fe33-O)(μ-4-NO2-pz)6X3]n- (X = Cl, Br, NCS, CN, py and, 4-Me-py; n = 2 and 3) show one reversible redox process, where the potential is fully dependent on the electron donating and/or withdrawing properties of the terminal ligand. One-electron reduction of the H.S. all-ferric thiocyanate complex, [Fe33-O)(μ-4-NO2-pz)6(SCN)3]2-, to its mixed-valent [Fe3]3- trianionic analogue triggers a cascade of H.S. to L.S. electronic reorganization. It is expected that terminal ligands with similar electron donating capacity like SCN (NCO and N3) will exhibit similar behavior. The all-ferric complexes [Fe33-O)(μ-4-NO2-pz)6(NCO)3]2- (A) and [Fe33-O)(μ-4-NO2-pz)6(N3)3]2- (B) have been synthesized by substitution of terminal Cl ligands of the parent compound [Fe33-O)(μ-4-NO2-pz)6Cl3]2- using NaNCO and NaN3. Complexes A and B were characterized by single crystal X-ray diffraction, UV-Vis-NIR, 1H-NMR, 57Fe-Mössbauer and cyclic voltammetry. Expected reversible reduction processes were observed for both complexes at more cathodic potential, -0.70 V,  than the thiocyanate complex (-0.36 V). Additionally, compound 2 shows a unique reversible oxidation process at 0.82 V (vs. Fc+/Fc) to [Fe33-O)(μ-4-NO2-pz)6(N3)3]-, a mixed-valent, formally Fe23+/ Fe4+ species.