title: Stable eight-coordinate iron(III/II) complexes.
abstract: The chemistry of unusual coordination numbers of transition-metal complexes has been of interest because of their presence in biology and catalytic systems. Herein we describe a systematic and predictable approach toward isolation of stable eight-coordinate (8C) iron(III/II) systems. The 8C (S = 2; high-spin, HS) complex [Fe(L(N4))(2)](BF(4))(2) (1) has been synthesized and characterized, displaying a distorted square-antiprism structure. Complex 1 is a unique 8C iron complex that exhibits remarkable stability in solution under various unfavorable conditions. The E(1/2) value of 1 (0.430 V vs Ag/AgCl, MeCN) supports the Fe(II) oxidation state; however, the corresponding HS (S = 5/2) 8C Fe(III) analogue [Fe(L(N4))(2)](NO(3))(3) (3) has also been synthesized via the chemical oxidation of 1. The structural, spectroscopic, and theoretical descriptions of these 8C iron complexes are reported in this work.
authors.affiliation: Department of Chemistry, The University of Georgia, Athens, Georgia 30602, USA.
authors.forename: Ashis K
authors.initials: AK
authors.lastname: Patra
authors.forename: Koustubh S
authors.initials: KS
authors.lastname: Dube
authors.forename: Georgia C
authors.initials: GC
authors.lastname: Papaefthymiou
authors.forename: Jeanet
authors.initials: J
authors.lastname: Conradie
authors.forename: Abhik
authors.initials: A
authors.lastname: Ghosh
authors.forename: Todd C
authors.initials: TC
authors.lastname: Harrop