Structural and 1H NMR spectroscopic characterization of bis(N-isopropylsalicylaldiminato)iron(II)

Michele A. Torzilli, Shalton Colquhoun, Jin Montclare, Robert H. Beer

Research output: Contribution to journalArticle

Abstract

Coordinatively unsaturated iron(II) species form reactive organometallic and coordination complexes and are integral to the reactivity of non-heme iron proteins and their synthetic analogues. Iron(II) Schiff base complexes have proven to be easily prepared and useful starting materials for such compounds. Here we report a detailed preparative procedure and the solid-state structure of the iron(II) complex of N-isopropylsalicylaldimine (LiprH) based on the compounds first synthesized by Larkworthy (J. Chem. Soc., A (1968) 1048). The title compound is prepared by adding 2 equiv. of salicylaldehyde (sa1H) to Fe(O2CCH3)2 in KOH-CH3OH to produce a precursor formulated as Fe(sal)2 which is reacted subsequently with isopropylamine in THF to form Fe(Lipr)2 in 34% isolated yield. A single crystal X-ray crystallographic study of Fe(Lipr)2 reveals a mononuclear complex with two bidentate salicylaldiminate ligands bound to an iron(II) atom in a tetrahedral coordination geometry. The 1H NMR spectrum of Fe(Lipr)2 in benzene-d6 exhibits six paramagnetically shifted ligand resonances ranging from +195 to -31 ppm that are consistent with a mononuclear high spin (S = 2) iron(II) complex in solution. Upon exposure to air, Fe(Lipr)2 forms the oxo-bridged dinuclear iron(III) complex [(Lipr)2Fe]2O as shown by 1H NMR spectroscopy.

Original languageEnglish (US)
Pages (from-to)705-713
Number of pages9
JournalPolyhedron
Volume21
Issue number7
DOIs
StatePublished - Apr 1 2002

Fingerprint

Iron
Nuclear magnetic resonance
iron
nuclear magnetic resonance
Nonheme Iron Proteins
Proton Magnetic Resonance Spectroscopy
Ligands
Schiff Bases
ligands
Coordination Complexes
Organometallics
Benzene
Nuclear magnetic resonance spectroscopy
imines
Magnetic Resonance Spectroscopy
Air
X-Rays
Single crystals
reactivity
benzene

Keywords

  • H NMR spectroscopy
  • Dioxygen reactivity
  • Iron(II)
  • Schiff base
  • X-ray crystal structures
  • Zinc(II)

ASJC Scopus subject areas

  • Biochemistry
  • Inorganic Chemistry
  • Physical and Theoretical Chemistry
  • Materials Chemistry

Cite this

Structural and 1H NMR spectroscopic characterization of bis(N-isopropylsalicylaldiminato)iron(II). / Torzilli, Michele A.; Colquhoun, Shalton; Montclare, Jin; Beer, Robert H.

In: Polyhedron, Vol. 21, No. 7, 01.04.2002, p. 705-713.

Research output: Contribution to journalArticle

Torzilli, Michele A. ; Colquhoun, Shalton ; Montclare, Jin ; Beer, Robert H. / Structural and 1H NMR spectroscopic characterization of bis(N-isopropylsalicylaldiminato)iron(II). In: Polyhedron. 2002 ; Vol. 21, No. 7. pp. 705-713.
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AB - Coordinatively unsaturated iron(II) species form reactive organometallic and coordination complexes and are integral to the reactivity of non-heme iron proteins and their synthetic analogues. Iron(II) Schiff base complexes have proven to be easily prepared and useful starting materials for such compounds. Here we report a detailed preparative procedure and the solid-state structure of the iron(II) complex of N-isopropylsalicylaldimine (LiprH) based on the compounds first synthesized by Larkworthy (J. Chem. Soc., A (1968) 1048). The title compound is prepared by adding 2 equiv. of salicylaldehyde (sa1H) to Fe(O2CCH3)2 in KOH-CH3OH to produce a precursor formulated as Fe(sal)2 which is reacted subsequently with isopropylamine in THF to form Fe(Lipr)2 in 34% isolated yield. A single crystal X-ray crystallographic study of Fe(Lipr)2 reveals a mononuclear complex with two bidentate salicylaldiminate ligands bound to an iron(II) atom in a tetrahedral coordination geometry. The 1H NMR spectrum of Fe(Lipr)2 in benzene-d6 exhibits six paramagnetically shifted ligand resonances ranging from +195 to -31 ppm that are consistent with a mononuclear high spin (S = 2) iron(II) complex in solution. Upon exposure to air, Fe(Lipr)2 forms the oxo-bridged dinuclear iron(III) complex [(Lipr)2Fe]2O as shown by 1H NMR spectroscopy.

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