Making Oxidation Potentials Predictable: Coordination of Additives Applied to the Electronic Fine Tuning of an Iron(II) Complex

Haslinger, Stefan; Kück, Jens W.; Hahn, Eva M.; Cokoja, Mirza; Pöthig, Alexander; Basset, Jean‐Marie; Kühn, Fritz E.

doi:10.1021/ic501613a

Cited by 30 publications

(37 citation statements)

References 76 publications

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“…In order to inhibit interconversion, an irreversible exchange of the acetonitrile ligands by PMe 3 was attempted. 47 Upon addition of excess PMe 3 to an acetonitrile solution of 13, di(PMe 3 ) substituted iron(II) complex 14 can be isolated (Scheme 5). Compared to complex 13, 1 H NMR recorded at room temperature exhibits sharp signals of only one species with a plane of symmetry as indicated by a single singlet signal for the terminal methyl groups and a single triplet signal for the methyl groups of the phosphine ligands.…”

Section: Transmetalation To Metals Of the Nickel Groupmentioning

confidence: 99%

Structural diversity of late transition metal complexes with flexible tetra-NHC ligands

et al. 2015

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The synthesis of copper, gold, nickel, palladium, platinum, and iron complexes with open chain tetra-N-heterocyclic carbene (NHC) ligands via transmetalation using silver NHC complexes is presented. The obtained complexes show differing coordination geometries depending on both ligand structure and metal. While the complexes of the coinage metals form di- or tetranuclear structures, the group 10 metal complexes exhibit a distorted square planar coordination geometry at the metal centers. In the case of iron an enhanced flexibility of the ligand - caused by a longer alkyl bridge - leads to octahedral complexes with a sawhorse-type coordination by the tetracarbene ligand and two cis acetonitrile ligands. To the best of our knowledge, this is the first known example of a tetracarbene ligand in sawhorse-type coordination within an octahedral coordination sphere. The remaining cis-labile sites are prone to exchange reactions as shown by addition of trimethylphosphine.

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Section: Transmetalation To Metals Of the Nickel Groupmentioning

confidence: 99%

Structural diversity of late transition metal complexes with flexible tetra-NHC ligands

et al. 2015

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“…With chemical shis of 8.75 ppm and 8.33 ppm both signals of the ortho protons of the pyridyl moieties are shied upeld compared to 9.26 ppm for 2a and 9.57 ppm for 1. 26,30 An additional conrmation of the trisubstitution pattern is given by ESI-MS data, showing a distinct signal at m/z 751.82.…”

Section: Syntheses Of Tri(isocyanide)-substituted Complexesmentioning

confidence: 99%

“…No exchange of the coordinating isocyanides by acetonitrile is observed, which stands in contrast to the observations reported for phosphine-based ligands. 30 …”

Section: Time-dependent Analysis Of Ligand Exchange Reactionmentioning

confidence: 99%

“…30 This was investigated both theoretically by DFT calculations and experimentally by determination of the half-cell potentials with cyclic voltammetry. While the half-cell potential of 1 was determined to be 423 mV (versus Fc/Fc + ), an exchange of only one acetonitrile ligand with PMe 3 reduced the half-cell potential to 325 mV.…”

Section: Electrochemical Investigationsmentioning

confidence: 99%

“…Finally, the impact of isocyanide ligands of the electronic structure of the obtained Fe(II) complexes is studied by cyclic voltammetry and the results are discussed in the context of previously reported ndings on the electronic tuning of Fe(II) complexes. 30 …”

Section: Introductionmentioning

confidence: 99%

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Isocyanide substitution reactions at the trans labile sites of an iron(ii) N-heterocyclic carbene complex

et al. 2015

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A variety of isocyanide-substituted Fe(II) N-heterocyclic carbene (NHC) complexes has been synthesized, starting from an Fe(II) NHC complex with an equatorial, tetradentate bis(pyridyl-NHC) ligand (NCCN).Depending on the relative amount of isocyanide used for the reaction either mono(isocyanide)-substituted or tri(isocyanide)-substituted Fe(II) complexes are obtained. In the case of the tri-substituted complexes single crystal X-ray diffraction reveals the dissociation of one of the pyridyl moieties of the tetradentate NCCN ligand, inducing a meridional, tridentate NCC coordination. As an intermediate for the formation of the tri-substituted complexes a cis di(CN t Bu)-substituted Fe(II) complex was identified by NMR spectroscopy. The impact of the isocyanide ligands on the electronic structure of the iron complexes was investigated by cyclic voltammetry, showing an increase in the required potential for the oxidation of Fe(II) to Fe(III) from 423 mV to up to 1092 mV.

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Predictable Electronic Tuning By Choice of Azine Substituent in Five Iron(II) Triazoles: Redox Properties and DFT Calculations

Rodríguez‐Jiménez

Bondì

Yang

et al. 2018

Chemistry An Asian Journal

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Five new mononuclear iron(II) tris‐ligand complexes, and four solvatomorphs, have been made from the azine‐substituted 1,2,4‐triazole ligands (Lazine): [FeII(Lpyridazine)3](BF4)2 (1), [FeII(Lpyrazine)3](BF4)2 (2), [FeII(Lpyridine)3](BF4)2 (3), [FeII(L2pyrimidine)3](BF4)2 (4), and [FeII(L4pyrimidine)3](BF4)2 (5). Single‐crystal XRD and solid‐state magnetometry reveal that all of them are low‐spin (LS) iron(II), except for solvatomorph 5⋅4 H2O. Evans method NMR studies in CD2Cl2, (CD3)2CO and CD3CN show that all are LS in these solvents, except 5 in CD2Cl2 (consistent with L4pyrimidine imposing the weakest field). Cyclic voltammetry in CH3CN vs. Ag/0.01 m AgNO3 reveals an, at best quasi‐reversible, FeIII/II redox process, with Epa increasing from 0.69 to 0.99 V as the azine changes: pyridine< pyridazine<2‐pyrimidine<4‐pyrimidine< pyrazine. The observed Epa values correlate linearly with the DFT calculated HOMO energies for the LS complexes.

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Making Oxidation Potentials Predictable: Coordination of Additives Applied to the Electronic Fine Tuning of an Iron(II) Complex

Cited by 30 publications

References 76 publications

Structural diversity of late transition metal complexes with flexible tetra-NHC ligands

Structural diversity of late transition metal complexes with flexible tetra-NHC ligands

Isocyanide substitution reactions at the trans labile sites of an iron(ii) N-heterocyclic carbene complex

Predictable Electronic Tuning By Choice of Azine Substituent in Five Iron(II) Triazoles: Redox Properties and DFT Calculations

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