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Low-Coordinate Iron Complexes Stabilized by N -( tert -Hydrocarbyl)anilide Ligation: Adduct Formation, Chemical Oxidation, and Nitric Oxide Complexation

1996; American Chemical Society; Volume: 15; Issue: 21 Linguagem: Inglês

10.1021/om960455q

1520-6041

Sheree Lynell Stokes, William M. Davis, Aaron L. Odom, Christopher C. Cummins,

Organometallic Complex Synthesis and Catalysis

Monomeric iron complexes supported by the new, sterically-demanding NRArF (R = C(CD3)2CH3, ArF = 2,5-C6H3FMe) and NR'ArF (R' = C(CD3)2Ph) ligands are described. Four-coordinate Fe(Cl)(TMEDA)(NRArF) (1) was isolated in 87% yield as a colorless solid. The bis(amide) complexes Fe(L)(NRArF)2 (L = pyridine-d5, 2; L = PEt3, 3) were isolated in 91% and 80% yields as orange-red and yellow solids, respectively. The related complex Fe(py-d5)(NR'ArF)2 (4) was prepared in 79% yield, characterized structurally by X-ray diffraction, and found to display chelation of the ArF residue via dative Fe···F interactions. The iodo complex Fe(I)(py-d5)(NRArF)2 (5) was obtained in 91% yield as a purple solid upon treatment of 2 with 1/2 equiv of iodine; according to an X-ray diffraction study 5 is a pseudotetrahedral monomer. The nitric oxide complexes Fe(NO)(L)(NRArF)2 (L = py-d5, 6; L = PEt3, 7) were obtained as wine red crystalline solids in 92% and 89% yields, respectively, upon treatment of 2 or 3 with a slight excess of gaseous nitric oxide. Nitric oxide abstraction from 6 was accomplished quantitatively upon treatment with Mo(NRAr)3 (Ar = 3,5-C6H3Me2) or with Cr(NiPr2)3, regenerating 2 and generating Mo(NO)(NRAr)3 or Cr(NO)(NiPr2)3. The homoleptic iron(II) amide [Fe(NRAr)(μ-NRAr)]2 (8) was obtained in 88% yield as a red-orange solid upon treatment of ethereal ferrous chloride with 2 equiv of Li(NRAr)(OEt2). "Ate" complex (ArRN)Fe(μ-NRAr)2Li(OEt2) (9) was obtained similarly through treatment of ferrous chloride with 3 equiv of Li(NRAr)(OEt2). Ferrocenium triflate oxidation of 9 gave the homoleptic iron(III) amide Fe(NRAr)3 (10) in 85% yield. All paramagnetic complexes studied here were characterized by magnetic susceptibility studies, by 2H NMR spectroscopy, and by elemental analysis.