title: Synthesis, characterization, and reactivity of iron(III) complexes supported by a trianionic ONO(3-) pincer ligand.
abstract: Synthetic and characterization results of a new family of Fe(III) compounds stabilized by a trianionic [CF3-ONO](3-) pincer-type ligand are reported. The ligand possesses three negatively charged donors constrained to the meridional positions that provide sufficient electron density to stabilize high-valent metal complexes. Using the redox-insulated [CF3-ONO](3-), pentacoordinated square-pyramidal {[CF3-ONO]FeCl2}{LiTHF2}2 (3), dimeric μ-DME{[CF3-ONO]FeDME}2 (4), trigonal bipyramidal [CF3-ONO]Fe(bpy) (5), and octahedral [CF3-ONO]Fe(bpy)H2O (5·H2O) complexes are synthesized. An interesting feature of the [CF3-ONO](3-) pincer-type ligand is its ability to coordinate the metal center in both the more common meridional positions or occupying a face of a trigonal bipyramidal complex. The molecular structure of 3 contains structural features similar to those of a rare square-planar high-spin Fe(II) complex, and the important role of the counterions in stabilizing a square-plane is emphasized. SQUID magnetometry measurements of 3 reveal its high-spin character, and cyclic voltammetry measurements indicate high oxidation state species are unstable. However, all compounds can be reduced, and in particular 5 displays a reversible reduction event at -2255 mV versus ferrocene (Fc(+)/Fc) that can be assigned to either the Fe(I)/Fe(0) couple or 2,2'-bipyridine reduction.
authors.affiliation: Department of Chemistry, ‡Center for Catalysis, and §Department of Physics and National High Magnetic Field Laboratory, University of Florida , Gainesville, Florida 32611, United States.
authors.forename: Matias E
authors.initials: ME
authors.lastname: Pascualini
authors.forename: Natali V
authors.initials: NV
authors.lastname: Di Russo
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Quintero
authors.forename: Annaliese E
authors.initials: AE
authors.lastname: Thuijs
authors.forename: Dawid
authors.initials: D
authors.lastname: Pinkowicz
authors.forename: Khalil A
authors.initials: KA
authors.lastname: Abboud
authors.forename: Kim R
authors.initials: KR
authors.lastname: Dunbar
authors.forename: George
authors.initials: G
authors.lastname: Christou
authors.forename: Mark W
authors.initials: MW
authors.lastname: Meisel
authors.forename: Adam S
authors.initials: AS
authors.lastname: Veige
mesh_terms: D015082:2,2'-Dipyridyl / Q000737:chemistry; D000838:Anions / Q000737:chemistry*; D002614:Chelating Agents / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D005296:Ferrous Compounds / Q000737:chemistry; D054879:Halogenation; D008024:Ligands; D000075163:Metallocenes; D010084:Oxidation-Reduction
chemical_list: D000838:Anions; D002614:Chelating Agents; D005290:Ferric Compounds; D005296:Ferrous Compounds; D008024:Ligands; D000075163:Metallocenes; D015082:2,2'-Dipyridyl; C004998:ferrocene