Discrete Tetrairon(III) Cluster Exhibiting a Square-Planar Fe₄(μ₄-O) Core: Structural and Magnetic Properties

Abstract

The aerobic reaction of the Schiff-base ligand N-(benzimidazol-2-yl)salicylaldimine (Hbisi) with iron(II) perchlorate in methanol leads to the formation of the remarkable coordination compound [Fe(4)(mu(4)-O)(mu-MeO)(4)(bisi)(4)](ClO(4))(2) x 4 MeOH (1), whose single-crystal X-ray structure reveals the presence of a discrete Fe(III)(4)(mu(4)-O) core. Magnetic and Mossbauer studies both show that the exchange interaction within the square tetranuclear iron(III) unit is dominated by the central bridging mu(4)-oxido ligand, the involvement of the mu-methoxido bridges being negligible.

Nitric Oxide Activation by Distal Redox Modulation in Tetranuclear Iron Nitrosyl Complexes

“…18 Oxidation of 6 to 8 results in an increase in the Lewis acidity of the triiron core, which in turn leads to a decrease in the Fe1|Fe2|Fe3 centroid–O1 distance from 1.057 Å ( 6 ) to 0.921 Å ( 8 ). Furthermore, oxidation also results in contraction of the Fe1– N13, Fe2–N23, and Fe3–N33 bond distances (Table 1).…”

Remote Ligand Modifications Tune Electronic Distribution and Reactivity in Site-Differentiated, High-Spin Iron Clusters: Flipping Scaling Relationships

“…52 Overall, the observed Mössbauer parameters for the irons in the trimetallic core are in-line with those of other six-coordinate Fe II /Fe III centers bearing N-and Odonor atoms. 35,[53][54][55][56][57] Simulation Details for [LFe3O( pCF3 ArIm)3Fe][OTf]2 (1 CF3 ): The zero-field Mössbauer spectrum (80 K) of 1 CF3 is nearly identical to that reported for 1 H , indicating a common electronic structure in both clusters. Based on their characteristic Mössbauer parameters, the asymmetric Lorentzian feature near 3 mm/s suggests the presence of at least high spin, six-coordinate ferrous centers.…”

“…Depending on how the resonances near 0.25 and 0.70 mm/s are modelled, the isomer shift of one of the subsites (δ = 0.36-0.50 mm/s, 25% total iron) is consistent with the presence of one sixcoordinate, high spin Fe III center in an O/N rich ligand environment. 35,[53][54][55][56][57] The quadrupole doublet of the remaining subsite has a significantly lower isomer shift (δ = 0.03-0.25 mm/s). Sixcoordinate ferric iron complexes are not known to exhibit isomer shifts in this range, suggesting either a low-spin assignment for the remaining Fe III center or a lower coordinate, highly covalent ligand field.…”

Syntheses, Crystal Structures, and Magnetic Properties of μ‐O/μ‐Cl Bridged Dinuclear Manganese(II) and Copper(II) Complexes with Schiff base Ligand HL [HL = 2‐(benzothiazol‐2‐yl‐hydrazonomethyl)‐6‐methoxyphenol]

“…Many Schiff‐base‐containing coordination compounds have shown attractive properties. For example, Schiff‐base coordination compounds exhibit interesting magnetic properties 4–9. Many Schiff‐base complexes have also found interesting applications in nonlinear optical,10–16 fluorescence properties,17 catalysis,18–22 DNA‐hydrolytic characters,23–25 and antibacterial behavior 26,27…”