Synthesis, characterization, electrochemical properties and theoretical calculations of (BIAN) iron complexes

Larson, Patrick; Wekesa, Francis S.; Singh, Arpita; Smith, Cecilia R.; Rajput, Amit; Unruh, Daniel K.; Cozzolino, Anthony F.; Findlater, Michael

doi:10.1016/j.poly.2018.11.060

Cited by 13 publications

(46 citation statements)

References 61 publications

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“…One reversible and at least one irreversible oxidation is observed. In the case of complex 1 , the chemically reversible process at E 1/2 = −1.98 V vs Fc/Fc + is consistent with previous results by Findlater and co-workers, who prepared the neutral complex [( Dipp BIAN)Fe(η 4 -cod)] by Na/Hg reduction of [( Dipp BIAN)FeCl 2 ] and cod . On the basis of the structural data obtained for the anionic complex 1 -[K([18]c-6)(thf) 0.5 ] (vide supra) and the neutral compound [( Dipp BIAN)Fe(η 4 -cod)] reported by Findlater and co-workers, both species presumably contain an Fe(I) center.…”

Section: Resultssupporting

confidence: 89%

“…As a result, the synthesis of low-valence α-diimine iron complexes bearing an unsaturated hydrocarbon as second ligand has attracted significant interest over the last two decades (Figure ). − In these complexes, the hydrocarbon is supposed to act as a “placeholder”, which is easily replaced by other substrates to initiate the catalytic cycle. These hydrocarbons are typically simple arenes as used for example in net-neutral complexes A – E shown in Figure synthesized by the groups of Zenneck ( A ), Chirik ( B ), Song ( C ), and Findlater ( D and E , all Figure ).…”

Section: Introductionmentioning

confidence: 99%

“…In the same report, the electronic structure of this complex was investigated with various techniques (SQUID magnetization measurements, 57 Fe Mössbauer spectroscopy, and DFT calculations), suggesting the presence of a high-spin Fe(I) ( S = 3/2) center, which is antiferromagnetically coupled to an α-diimine radical anion. Findlater and co-workers introduced the BIAN ligand in this class of complexes, resulting in the formation of complex [( Dipp BIAN)Fe(η 4 -cod)] ( I ) . The group of Chirik further contributed the neutral heteroleptic iron α-diimine complexes J and K .…”

Section: Introductionmentioning

confidence: 99%

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Low-Valence Anionic α-Diimine Iron Complexes: Synthesis, Characterization, and Catalytic Hydroboration Studies

et al. 2020

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The synthesis of rare anionic heteroleptic and homoleptic α-diimine iron complexes is described. Heteroleptic BIAN (bis(aryl)iminoacenaphthene) complexes 1-[K([18]c-6)-(thf) 0.5 ] and 2-[K([18]c-6)(thf) 2 ] were synthesized by reduction of the [(BIAN)FeBr 2 ] precursor complex using stoichiometric amounts of potassium graphite in the presence of the corresponding olefin. The electronic structure of these paramagnetic species was investigated by numerous spectroscopic analyses (NMR, EPR, 57 Fe Mossbauer, UV−vis), magnetic measurements (Evans NMR method, SQUID), and theoretical techniques (DFT, CASSCF). Whereas anion 1 is a low-spin complex, anion 2 consists of an intermediate-spin Fe(III) center. Both complexes are efficient precatalysts for the hydroboration of carbonyl compounds under mild reaction conditions. The reaction of bis(anthracene) ferrate(1−) gave the homoleptic BIAN complex 3-[K([18]c-6)(thf)], which is less catalytically active. The electronic structure was elucidated with the same techniques as described for complexes 1-[K([18]c-6)(thf) 0.5 ] and 2-[K([18]c-6)(thf) 2 ] and revealed an Fe(II) species in a quartet ground state.

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Section: Resultssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Low-Valence Anionic α-Diimine Iron Complexes: Synthesis, Characterization, and Catalytic Hydroboration Studies

et al. 2020

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“…Electronically, it can act as a reservoir, whereby electrons can be transferred with ease between the ligand and the central atom. [74][75][76][77][78][79] For example, in complexes with early transition metals, this ligand system has displayed electronic properties such as delocalization, [80][81] intramolecular electron transfer, 82 and valence tautomerism. 80 The bifunctional BIAN derivative, tetrakis(imino)pyracene (TIP), has been developed by Cowley and coworkers; 83 and similar to its parent, electron transfer between the ligand and a central atom has been observed.…”

Section: Introductionmentioning

confidence: 99%

Unusually Strong Long-range Electronic Coupling Across Redox-Active Bridges in M3+/M4+ Mixed-Valence Complexes of Group 4 Congeners

Bell

DeYonker

Moore

et al. 2021

Preprint

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Section: Introductionmentioning

confidence: 99%

Unusually Strong Long-range Electronic Coupling Across Redox-Active Bridges in M3+/M4+ Mixed-Valence Complexes of Group 4 Congeners

Bell

DeYonker

Moore

et al. 2021

Preprint

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Homobimetallic complexes of Group 4 metals, supported by the redox-active tetrakis(imino)pyracene (TIP) ligand were synthesized and isolated. The formation of these complexes resulted in LUMOs having significantly lower energies than the free ligand and the respective metal salts, MCl4 (M = Ti, Zr, Hf), whereby all three complexes were readily reduced by one electron using the mild reductant, Cp*2Fe (E0 = -0.59 V). Spectroscopic characterization and quantum chemical analyses of the reduced species revealed that the resulting complexes are delocalized, borderline Class II-III (Ti) and Class III (Zr, Hf) mixed valence complexes. All three complexes display surprisingly strong long-range electronic coupling between the metal centers, as M to M distances, rAB, are nearly 12 Å. The coupling strengths of Zr and Hf were significantly stronger than those observed for the Ti complex, suggesting that better orbital overlap between the ligand and 4d or 5d metal centers helps to relieve the instability of the 3+ oxidation state via delocalization.

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Synthesis, characterization, electrochemical properties and theoretical calculations of (BIAN) iron complexes

Cited by 13 publications

References 61 publications

Low-Valence Anionic α-Diimine Iron Complexes: Synthesis, Characterization, and Catalytic Hydroboration Studies

Low-Valence Anionic α-Diimine Iron Complexes: Synthesis, Characterization, and Catalytic Hydroboration Studies

Unusually Strong Long-range Electronic Coupling Across Redox-Active Bridges in M3+/M4+ Mixed-Valence Complexes of Group 4 Congeners

Unusually Strong Long-range Electronic Coupling Across Redox-Active Bridges in M3+/M4+ Mixed-Valence Complexes of Group 4 Congeners

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