Synthesis and Characterization of Two Intensely Colored Tris(benzoylcyanoxime)iron(II) Anionic Complexes
Two intensely blue-colored complexes, P(C6H5) 4[Fe(BCO)3] (1) and Na[Fe(BCO)3] (2), where BCO- is the benzoylcyanoxime anion, have been prepared and characterized in solution and in the solid state. The crystal structure of 1 has been determined at several temperatures (100, 155, 225, and 293 K) and consists of layers of P(C6H5)4+ cations and [Fe(BCO)3]- anions. The latter exist as a pair of fac-Δ and Λ enantiomers in a monoclinic unit cell in the P2(1)/n space group. Iron(II) has a trigonal-prismatic N3O3 coordination environment with average Fe-N and Fe-O bond distances of 1.866 and 1.956 Å, respectively, bonds that are unusually short and indicate a 1A1g low-spin ground state for iron(II). A sample of 1 prepared with iron-57 has been studied by Mössbauer spectroscopy between 4.2 and 430 K and found to be low-spin iron(II) in studied temperature range. The stepwise formation constants for 1 in aqueous solution at 296 K and pH of 7 are log ß1 = 0.85 ± 0.1, log ß2 = 3.55 ± 0.15, and log ß3 = 6.36 ± 0.15. Both 1 and 2 exhibit irreversible oxidation of iron(II) at ~1.0 V, indicating a significant degree of the ligand-to-iron charge transfer. Thus, 1 and 2 are rare examples of highly colored iron(II) anionic complexes that do not contain aromatic heterocyclic amine ligands, such as bipyridine or phenanthroline.
T. M. Owen et al., "Synthesis and Characterization of Two Intensely Colored Tris(benzoylcyanoxime)iron(II) Anionic Complexes," Inorganic Chemistry, vol. 47, no. 19, pp. 8704-8713, American Chemical Society (ACS), Oct 2008.
The definitive version is available at http://dx.doi.org/10.1021/ic8004322
Keywords and Phrases
Ferrous Ion; Organometallic Compound; Oxime; Chemistry; Color; Electrochemistry; Mössbauer Spectroscopy; Nuclear Magnetic Resonance Spectroscopy; Synthesis; Ultraviolet Spectrophotometry; X Ray Crystallography; Color; Crystallography; X-Ray; Electrochemistry; Ferrous Compounds; Magnetic Resonance Spectroscopy; Organometallic Compounds; Oximes; Spectrophotometry; Ultraviolet; Spectroscopy; Mössbauer
International Standard Serial Number (ISSN)
Article - Journal
© 2008 American Chemical Society (ACS), All rights reserved.