Molecular and Electronic Structure of a Nonheme Iron(II) Model Complex Containing an Iron−Carbon Bond

Abstract

The synthesis and molecular structure of a novel iron(II) complex of an acyclic non-NHC bis(2-pyridylthio)carbene ligand containing a S-N-C facial triad are discussed. The iron carbene complex is formed in situ during the reaction of tris(2-pyridylthio)methane with an iron(II) salt. In the six-coordinate iron(II) complex, a strong Fe-C interaction (1.776 A) is observed crystallographically and the complex exhibits a singlet-spin ground state. Density functional theory calculations that reproduce the geometry as well as the spin ground state indicate that the electronic structure of the complex is best described as an iron(II) carbene. The carbene center is stabilized by extensive back-bonding from iron(II) and delocalization into the adjacent thiopyridine units.

Dioxygen Reactivity of Biomimetic Iron–Catecholate and Iron–o‐Aminophenolate Complexes of a Tris(2‐pyridylthio)methanido Ligand: Aromatic CC Bond Cleavage of Catecholate versus o‐Iminobenzosemiquinonate Radical Formation

“…Recently, the active site structure of [Fe]‐hydrogenase (Hmd) revealed an iron(II) centre with the coordination environment consisting of a pyridine nitrogen, a thiolate sulfur and an acyl carbon 6. 7 This has sparked and fuelled the interest to develop model complexes with the ironcarbon bond 8–15. Complexes with ironcarbon bonds are synthesised either by oxidative addition of the ligand containing the CH bond at a low‐valent iron centre or by coordination of a deprotonated carbanionic ligand at an iron(II) centre.…”

“…Applying the latter strategy, we have recently reported the synthesis, structure and reactivity of iron(II)carbon bonded complexes derived from tris(2‐pyridylthio)methane (HL 1 ) 15, 16 The sulfur‐stabilised anion of HL 1 binds to the iron(II) centre as a tetradentate carbanionic N 3 C donor ligand 16. The N 3 C ligand derived from HL 1 is useful for the synthesis of biomimetic models for oxygen‐activating non‐heme iron enzymes because the iron(II) complexes of this ligand would provide two labile cis coordination sites for exogenous substrates and dioxygen.…”

Fe–N 2 /CO complexes that model a possible role for the interstitial C atom of FeMo-cofactor (FeMoco)

“…Although a number of such ligands featuring a central C atom has been described (17)(18)(19) we reasoned that an alkyl ligand featuring only electropositive substituents adjacent to the C-atom anchor would provide a crude model of the interstitial carbide of the FeMoco and permit a high degree of ionic bonding to a single Fe-N 2 binding site. To achieve this goal, the C-atom anchor of the auxiliary ligand described is surrounded by three electropositive Si centers, in addition to the Fe site.…”

Probing the Reactivity of Redox‐Active 2‐Aminophenolates on Iron Complexes of a Carbanionic N3C Donor Ligand

“…in ethanol. [10] The iron(II)-acetonitrile complex [(L 1 )Fe II (CH 3 CN) 2 ] + (1) was synthesized by mixing a basic solution of HL 1 with iron(II) triflate in dichloromethane followed by the addition of an acetonitrile solution of sodium perchlorate.…”