Jahn-Teller distortion, ferromagnetic coupling, and electron delocalization in a high-spin Fe–Fe bonded dimer

Timmer, George H.; Berry, John F.

doi:10.1016/j.crci.2011.09.001

Cited by 20 publications

(13 citation statements)

References 86 publications

(52 reference statements)

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“…This can be rationalized by the fact that the Cl − is donating far less electron density than the apical phosphinoamide in 4. The Fe−Fe distance in the symmetrically bridged tetragonal lantern complex Fe 2 (DPhF) 4 (2.462(2) Å 44,45 ) is significantly shorter than those in 4 or 6. This phenomenon can be tentatively attributed to the two disparate coordination environments of the two Fe centers in 4 and 6 and the resulting differences in orbital energies, leading to poorer overlap between the metal d orbitals.…”

Section: ■ Results and Discussionmentioning

confidence: 93%

“…43 The electronic structure of a similar 4-fold symmetric formamidinate complex Fe 2 (DPhF) 4 44 has also been investigated computationally by Berry and coworkers. 45 In contrast to iron systems, high spin polynuclear manganese complexes tend to exhibit antiferromagnetic coupling and weaker metal−metal interactions. 2,46−50 To date, all of the reported non-organometallic metal−metal bonded first row transition metal complexes in the literature are supported by symmetric ligand sets that present identical donors to both Fe centers, providing a high degree of delocalization.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Cotton and co-workers provided a preliminary explanation for the nature of the metal–metal bonding in Fe 2 (DPhF) 3 , and Lu and co-workers recently revisited this rare example of a ferromagnetically coupled metal–metal bonded compound using advanced computational and spectroscopic methods . The electronic structure of a similar 4-fold symmetric formamidinate complex Fe 2 (DPhF) 4 has also been investigated computationally by Berry and co-workers . In contrast to iron systems, high spin polynuclear manganese complexes tend to exhibit antiferromagnetic coupling and weaker metal–metal interactions. ,− …”

Section: Introductionmentioning

confidence: 99%

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Utilization of Phosphinoamide Ligands in Homobimetallic Fe and Mn Complexes: The Effect of Disparate Coordination Environments on Metal–Metal Interactions and Magnetic and Redox Properties

et al. 2012

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A series of homobimetallic phosphinoamide-bridged diiron and dimanganese complexes in which the two metals maintain different coordination environments have been synthesized. Systematic variation of the steric and electronic properties of the phosphinoamide phosphorus and nitrogen substituents leads to structurally different complexes. Reaction of [(i)PrNKPPh(2)] (1) with MCl(2) (M = Mn, Fe) affords the phosphinoamide-bridged bimetallic complexes [Mn((i)PrNPPh(2))(3)Mn((i)PrNPPh(2))] (3) and [Fe((i)PrNPPh(2))(3)Fe((i)PrNPPh(2))] (4). Complexes 3 and 4 are iso-structural, with one metal center preferentially binding to the three amide ligands in a trigonal planar arrangement while the second metal center is ligated by three phosphine donors. A fourth phosphinoamide ligand caps the tetrahedral coordination sphere of the phosphine-ligated metal center. Mössbauer spectroscopy of complex 4 suggests that the metals in these complexes are best described as Fe(II) centers. In contrast, treatment of MnCl(2) or FeI(2) with [MesNKP(i)Pr(2)] (2) leads to the formation of the halide-bridged species [(THF)Mn(μ-Cl)(MesNP(i)Pr(2))(2)Mn(MesNP(i)Pr(2))] (5) and [(THF)Fe(μ-I)(MesNP(i)Pr(2))(2)FeI (7), respectively. Utilization of FeCl(2) in place of FeI(2), however, leads exclusively to the C(3)-symmetric complex [Fe(MesNP(i)Pr(2))(3)FeCl] (6), structurally similar to 4 but with a halide bound to the phosphine-ligated Fe center. The Mössbauer spectrum of 6 is also consistent with high spin Fe(II) centers. Thus, in the case of the [(i)PrNPPh(2)](-) and [MesNP(i)Pr(2)](-) ligands, zwitterionic complexes with the two metals in disparate coordination environments are preferentially formed. In the case of the more electron-rich ligand [(i)PrNP(i)Pr(2)](-), complexes with a 2:1 mixed donor ligand arrangement, in which one of the ligand arms has reversed orientation relative to the previous examples, are formed exclusively when [(i)PrNLiP(i)Pr(2)] (generated in situ) is treated with MCl(2) (M = Mn, Fe): (THF)(3)LiCl[Mn(N(i)PrP(i)Pr(2))(2)(P(i)Pr(2)N(i)Pr)MnCl] (8) and [Fe(N(i)PrP(i)Pr(2))(2)(P(i)Pr(2)N(i)Pr)FeCl] (9). Bimetallic complexes 3-9 have been structurally characterized using X-ray crystallography, revealing Fe-Fe interatomic distances indicative of metal-metal bonding in complexes 6 and 9 (and perhaps 4, to a lesser extent). All of the complexes appear to adopt high spin electron configurations, and magnetic measurements indicate significant antiferromagnetic interactions in Mn(2) complexes 5 and 8 and no discernible magnetic superexchange in Fe(2) complex 4. The redox behavior of complexes 3-9 has also been investigated using cyclic voltammetry, and theoretical investigations (DFT) were performed to gain insight into the metal-metal interactions in these unique asymmetric complexes.

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Section: ■ Results and Discussionmentioning

confidence: 93%

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Utilization of Phosphinoamide Ligands in Homobimetallic Fe and Mn Complexes: The Effect of Disparate Coordination Environments on Metal–Metal Interactions and Magnetic and Redox Properties

et al. 2012

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“…However, these kind of methods are not amenable for so big systems. Thus, we have used the spin-unrestricted approximation and the broken-symmetry solution (BS) within the DFT framework, that showed to provide a good description of weakly bonded metal-metal interactions [6,24].…”

Section: Introductionmentioning

confidence: 99%

Second-Row Transition-Metal Doping of (ZniSi), i = 12, 16 Nanoclusters: Structural and Magnetic Properties

et al. 2013

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TM@Zn i S i nanoclusters have been characterized by means of the Density Functional Theory, in which Transition Metal (TM) stands from Y to Cd, and i = 12 and 16. These two nanoclusters have been chosen owing to their highly spheroidal shape which allow for favored endohedral structures as compared to other nanoclusters. Doping with TM is chosen due to their magnetic properties. In similar cluster-assembled materials, these magnetic properties are related to the Transition Metal-Transition Metal (TM-TM) distances. At this point, endohedral doping presents a clear advantage over substitutional or exohedral doping, since in the cluster-assembled materials, these TM would occupy the well-fixed center of the cluster, providing in this way a better TM-TM distance control to experimentalists. In addition to endohedral compounds, surface structures and the TS's connecting both isomers have been characterized. In this way the kinetic and thermal stability of endohedral nanoclusters is predicted. We anticipate that silver and cadmium endohedrally doped nanoclusters have the longest lifetimes. This is due to the weak interaction of these metals with the cage, in contrast to the remaining cases where the TM covalently bond to a region of the cage. The open-shell electronic structure of Ag provides magnetic properties to Ag@Zn i S i clusters. Therefore, we have further characterized (Ag@Zn 12 S 12) 2 and (Ag@Zn 16 S 16) 2 dimers both in the ferromagnetic and antiferromagnetic state, in order to calculate the corresponding magnetic exchange coupling constant, J.

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“…In an effort to try and rationalize the molecular spin observed for Fe 3 L 3 , one can consider a qualitative frontier orbital analysis derived from the results of computational methods for tetragonal diferrous 32 and M 3 (dpa) 4 Cl 2 7 complexes (adjusting for the lack of axial ligands) and modified to account for the local trigonal coordination geometry akin to the methodology employed by Krogman and Thomas 31 for bimetallic complexes (Figure S11). Assuming D 3 symmetry and a spin-only system, the generation of symmetry-adapted linear combinations from the 15 iron-based 3d orbitals leads to 5 bonding, 5 nonbonding, and 5 antibonding molecular orbitals.…”

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confidence: 99%

Synthesis and Characterization of a Linear Triiron(II) Extended Metal Atom Chain Complex with Fe–Fe Bonds

et al. 2020

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Extended metal atom chain (EMAC) complexes of first-row transition metals with metal−metal bonds have the potential to elicit unique magnetic properties and reactivities. Until now, the library of EMAC complexes with late-first-row transition metals was incomplete because of the omission of a triiron species with Fe−Fe bonding. Herein we report the synthesis and preliminary investigation of the first linear, triiron(II) complex containing close Fe−Fe interactions. The complex is supported by three dianionic 2,6-bis[(trimethylsilyl)amido]pyridine ligands (L), with an overall composition of Fe 3 L 3 , and pseudohelical ligand coordination stabilizing the local trigonal-planar geometry at each iron. Fe 3 L 3 was characterized by X-ray diffraction, 1 H NMR, cyclic voltammetry, electronic absorption, and Mossbauer spectroscopies. Evans method analysis indicated a large uncompensated spin and an S = 6 ground state, suggesting ferromagnetic coupling in the triiron chain, likely due to direct exchange.

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Jahn-Teller distortion, ferromagnetic coupling, and electron delocalization in a high-spin Fe–Fe bonded dimer

Cited by 20 publications

References 86 publications

Utilization of Phosphinoamide Ligands in Homobimetallic Fe and Mn Complexes: The Effect of Disparate Coordination Environments on Metal–Metal Interactions and Magnetic and Redox Properties

Utilization of Phosphinoamide Ligands in Homobimetallic Fe and Mn Complexes: The Effect of Disparate Coordination Environments on Metal–Metal Interactions and Magnetic and Redox Properties

Second-Row Transition-Metal Doping of (ZniSi), i = 12, 16 Nanoclusters: Structural and Magnetic Properties

Synthesis and Characterization of a Linear Triiron(II) Extended Metal Atom Chain Complex with Fe–Fe Bonds

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