Stabilization of High‐Valent FeIVS6‐Cores by Dithiocarbamate(1−) and 1,2‐Dithiolate(2−) Ligands in Octahedral [FeIV(Et2dtc)3−n(mnt)n](n−1)− Complexes (n=0, 1, 2, 3): A Spectroscopic and Density Functional Theory Computational Study

Milsmann, Carsten; Sproules, Stephen; Bill, Eckhard; Weyhermüller, Thomas; DeBeer, Serena; Wieghardt, Karl

doi:10.1002/chem.200903381

Cited by 21 publications

(11 citation statements)

References 67 publications

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“…81 The electron-withdrawing effect of the cyano substituents in [PPh 4 ] 2 [W IV (mnt) 3 ] shifts the peak to an energy higher than for other dithiolene types, as has been observed repeatedly in S K-edge spectra. 11,14,16,80 …”

Section: Resultsmentioning

confidence: 99%

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X-ray Absorption Spectroscopy Systematics at the Tungsten L-Edge

et al. 2014

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A series of mononuclear six-coordinate tungsten compounds spanning formal oxidation states from 0 to +VI, largely in a ligand environment of inert chloride and/or phosphine, was interrogated by tungsten L-edge X-ray absorption spectroscopy. The L-edge spectra of this compound set, comprised of [W0(PMe3)6], [WIICl2(PMePh2)4], [WIIICl2(dppe)2][PF6] (dppe = 1,2-bis(diphenylphosphino)ethane), [WIVCl4(PMePh2)2], [WV(NPh)Cl3(PMe3)2], and [WVICl6], correlate with formal oxidation state and have usefulness as references for the interpretation of the L-edge spectra of tungsten compounds with redox-active ligands and ambiguous electronic structure descriptions. The utility of these spectra arises from the combined correlation of the estimated branching ratio of the L3,2-edges and the L1 rising-edge energy with metal Zeff, thereby permitting an assessment of effective metal oxidation state. An application of these reference spectra is illustrated by their use as backdrop for the L-edge X-ray absorption spectra of [WIV(mdt)2(CO)2] and [WIV(mdt)2(CN)2]2– (mdt2– = 1,2-dimethylethene-1,2-dithiolate), which shows that both compounds are effectively WIV species even though the mdt ligands exist at different redox levels in the two compounds. Use of metal L-edge XAS to assess a compound of uncertain formulation requires: (1) Placement of that data within the context of spectra offered by unambiguous calibrant compounds, preferably with the same coordination number and similar metal ligand distances. Such spectra assist in defining upper and/or lower limits for metal Zeff in the species of interest. (2) Evaluation of that data in conjunction with information from other physical methods, especially ligand K-edge XAS. (3) Increased care in interpretation if strong π-acceptor ligands, particularly CO, or π-donor ligands are present. The electron-withdrawing/donating nature of these ligand types, combined with relatively short metal–ligand distances, exaggerate the difference between formal oxidation state and metal Zeff or, as in the case of [WIV(mdt)2(CO)2], exert the subtle effect of modulating the redox level of other ligands in the coordination sphere.

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Section: Resultsmentioning

confidence: 99%

“…13 At this high resolution (1–1.5 eV), the pre-edge transition is the preferred metric for Z eff . 14−17 The corresponding K-edge for third row metals occurs at prohibitively high energies (>60 keV). Consequently, attaining detail about the local electronic structure is confined to L-edge XAS.…”

Section: Introductionmentioning

confidence: 99%

X-ray Absorption Spectroscopy Systematics at the Tungsten L-Edge

et al. 2014

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“…Although many reports dedicated to bioinspired oxo (Fe IV,V =O), nitrido (Fe IV,V ≡N) and imido (Fe IV =N–R) iron compounds have been published since 2000 (refs 8, 12, 13, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33), new examples of non-biomimetic high-valent iron complexes are rare and remain much less explored343536. The most recent examples of such compounds are astonishing iron(IV) salts of the decamethylferrocene dication reported by Malischewski et al 37.…”

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Indefinitely stable iron(IV) cage complexes formed in water by air oxidation

et al. 2017

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In nature, iron, the fourth most abundant element of the Earth's crust, occurs in its stable forms either as the native metal or in its compounds in the +2 or +3 (low-valent) oxidation states. High-valent iron (+4, +5, +6) compounds are not formed spontaneously at ambient conditions, and the ones obtained synthetically appear to be unstable in polar organic solvents, especially aqueous solutions, and this is what limits their studies and use. Here we describe unprecedented iron(IV) hexahydrazide clathrochelate complexes that are assembled in alkaline aqueous media from iron(III) salts, oxalodihydrazide and formaldehyde in the course of a metal-templated reaction accompanied by air oxidation. The complexes can exist indefinitely at ambient conditions without any sign of decomposition in water, nonaqueous solutions and in the solid state. We anticipate that our findings may open a way to aqueous solution and polynuclear high-valent iron chemistry that remains underexplored and presents an important challenge.

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“…33 The structure of a putative Fe IV complex, [AsPh 4 ] 2 [Fe(mnt) 3 ], was reported as early as in 1973, 34 and since then other Fe IV and Fe III complexes have been structurally examined. 35 [Fe(mnt) 3 ] 2À/3À complexes are low spin due to the strong ligand eld of mnt and exhibit a distorted octahedral geometry. 32,36 More recently, Milsmann et al explored the electronic structure of both [Fe(mnt) 3 ] 2À and [Fe(mnt) 3 ] 3À complexes, demonstrating that the oxidation of Fe III to Fe IV was purely metal based.…”

Section: Introductionmentioning

confidence: 99%

“…32,36 More recently, Milsmann et al explored the electronic structure of both [Fe(mnt) 3 ] 2À and [Fe(mnt) 3 ] 3À complexes, demonstrating that the oxidation of Fe III to Fe IV was purely metal based. 35 For a more complete understanding of Fe dithiolene chemistry; the properties of Fe complexes with fully oxidized Dt 0 ligands must be thoroughly characterized. The only reported tris chelate [ 37 In this case, N,N 0 -dimethyl piperazine-2,3-dithione (Me 2 Dt 0 ) supported a low-spin conguration.…”

Section: Introductionmentioning

confidence: 99%