Photochemical Alkyne Insertions into the Iron–Thiocarbonyl Bond of [Fe2(CS)(CO)3(Cp)2]

Marchetti, Fabio; Zacchini, Stefano; Zanotti, Valerio

doi:10.1021/acs.organomet.6b00349

Cited by 17 publications

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“…The reaction requires photolytic activation in order to remove one CO, and the insertion of monosubstituted alkynes into the Fe-C bond is regioselective, with the less hindered alkyne carbon bound to the imine carbon (as shown in Scheme 5). The alkyne insertion described above is consistent with analogous reactions observed in diiron complexes of the type [Fe 2 (Cp) 2 (CO) 3 (L)] in which alkynes insert into the Fe-bridging L ligands (L = CO [67,68], CS [69]). Isocyanide insertion into iron bridging hydride bond is observed in the dinuclear complex [Fe2(μ-H)(μ-PCy2)(CO)4(μ-CO)(dppm)] (8), leading to the formation of the bridging formimidoyl complex 9 (Scheme 4) [61].…”

Section: Insertion Reactions Involving Isocyanides In Diiron Complexessupporting

confidence: 81%

Bond Forming Reactions Involving Isocyanides at Diiron Complexes

et al. 2019

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The versatility of isocyanides (CNR) in organic chemistry has been tremendously enhanced by continuous advancement in transition metal catalysis. On the other hand, the urgent need for new and more sustainable synthetic strategies based on abundant and environmental-friendly metals are shifting the focus towards iron-assisted or iron-catalyzed reactions. Diiron complexes, taking advantage of peculiar activation modes and reaction profiles associated with multisite coordination, have the potential to compensate the lower activity of Fe compared to other transition metals, in order to activate CNR ligands. A number of reactions reported in the literature shows that diiron organometallic complexes can effectively assist and promote most of the “classic” isocyanide transformations, including CNR conversion into carbyne and carbene ligands, CNR insertion, and coupling reactions with other active molecular fragments in a cascade sequence. The aim is to evidence the potential offered by diiron coordination of isocyanides for the development of new and more sustainable synthetic strategies for the construction of complex molecular architectures.

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Section: Insertion Reactions Involving Isocyanides In Diiron Complexessupporting

confidence: 81%

Bond Forming Reactions Involving Isocyanides at Diiron Complexes

et al. 2019

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“…Accordingly, diiron systems [Fe 2 Cp 2 (CO) 3 (L)] undergo alkyne insertion into the bond between one iron and a bridging ligand (L) isolobal to CO, i.e. thiocarbonyl or isocyanide, the reaction being initiated by photolytic displacement of one carbonyl. These reactions may require long times, give low yields and not be regioselective.…”

Section: Reactivity Of Aminoalkylidyne Complexesmentioning

confidence: 99%

Constructing Organometallic Architectures from Aminoalkylidyne Diiron Complexes

Marchetti

2018

Eur J Inorg Chem

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The chemistry of diiron complexes has seen a recent renaissance, due to the prominent role played by the element iron in the development of sustainable synthetic processes and the cooperative effects provided by two metal centers working in concert, that is a concept amazingly exploited by Nature. Aminoalkylidyne derivatives of [Fe 2 Cp 2 (CO) 4 ] are a convenient scaffold to grow organic fragments; in particular, the facile re-[a] received his PhD degree in Chemistry from the University of Bologna in 2003, then he moved to the University of Pisa in 2006, where he is currently Professor of Inorganic Chemistry. He has co-authored over 150 papers in international journals, dealing with several aspects of the coordination chemistry of transition metal compounds. He was awarded the Nasini Prize by the Italian Chemical Society in 2014, for his contribution to the chemistry of group 5 and 6 metal compounds and to the exploration of unconventional modes of metal mediated C-C bond formation. 3990 Scheme 7. Coupling of isocyanide ligands promoted by acetylide addition to aminoalkylidyne complexes. (a) R = Xyl, R′ = Ph; R = Xyl, R′ = 4-C 6 H 4 Me; R = Me, R′ = Ph. (b) γ-Al 2 O 3 , R′ = SiMe 3 . [51]Eur. 3991Scheme 8. Base-assisted coupling of aminoalkylidyne ligand (R = Me, Xyl or 4-C 6 H 4 OMe) with (a) alkenes (R′ = H, R′′ = CN, CO 2 Me, Ph; R′ = R′′ = CO 2 Et) [53] and (b) allenes (R′ = R′′ = Me; R′ = Me, CO 2 Et, R′′ = H). [54] Scheme 9. Synthesis of vinyliminium complexes via alkyne insertion into Fe-μ-carbyne bond. Inset: possible forms of isomerism. [61][62][63] Eur.

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“…5 The construction of organometallic motifs supported on the [Fe2Cp2(CO)x] skeleton has witnessed a renewed interest, 6 in view of the current huge effort to develop sustainable synthetic routes based on earth abundant metals, 7 and the awareness that Nature uses diiron organometallic units to perform amazingly-efficient enzymatic processes. 8 Diiron compounds [Fe2Cp2(CO) 3(L)] are known to undergo alkyne insertion between one Fe atom and the bridging L ligand, the latter being CO 9 or a fragment isolobal to CO (i.e., thiocarbonyl 10 or isocyanide 11 ), see Scheme 1. This general reaction requires the preliminary photolytic displacement of one terminal carbonyl ligand, in order to generate a vacant site available to the entrance of the alkyne.…”

Section: Introductionmentioning

confidence: 99%

DFT Mechanistic Insights into the Alkyne Insertion Reaction Affording Diiron μ-Vinyliminium Complexes and New Functionalization Pathways

et al. 2018

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Insertion of propyne or 2-butyne into the Fe-carbyne bond belonging to the fragment [Fe2Cp2(CO)(µ-CO){µ-CNMe(R)}] + (R = Me or Xyl = 2,6-C6H3Me2) was DFT investigated, and plausible intermediates were identified along the formation of the vinyliminium complexes [Fe2Cp2(CO)(µ-CO){µ-η 1 :η 3 -C(Me)C(R′′)CN(Me)(R)}]SO3CF3, [2a-d] + , thus allowing to explain regio-and stereochemical features. The X-ray structure of [2a]SO3CF3 (R = Me, R′′ = H) was determined by single crystal X-ray diffraction. Novel C-C and C-S bond forming pathways involving the vinyliminium ligand were then explored. Thus, [2b]SO3CF3 (R = Xyl, R′′ = H) reacted with cyclopentadiene (or cyclopentene), triphenylphosphonium methylide and benzyl bromide, in tetrahydrofuran in the presence of sodium hydride, to give respectively [Fe2Cp2(CO)(µ-CO){µ-η 1 :η 2 -C(Me)C{C(CH)4}CN(Me)(Xyl)}], 3, [Fe2Cp2(CO)(µ-CO){µ-η 1 :η 2 -C(Me)C(CH2)CN(Me)(Xyl)}], 4, and [Fe2Cp2(CO)(µ-CO){µ-η 1 :η 3 -C(Me)C(CH2Ph)CN(Me)(Xyl)}]Br, [5]Br, in good yields. The unstable complex 4 (detected by IR spectroscopy) readily converted into [2c]SO3CF3 (R = Xyl, R′′ = Me) upon HSO3CF3 protonation of the methylide function. [5]Br was obtained as E/Z isomeric mixture, which was then quantitatively converted into the most stable Z form, by heating in methanol solution at 50 °C. The reactions of [2cd]SO3CF3 (R = Me, Xyl, R′′ = Me) with PhSSPh/NaH selectively yielded the aminoalkylidyne species [Fe2Cp2(SPh)(CO)(µ-CO){µ-CN(Me)(Xyl)}], 6, and the bis-alkylidene [Fe2Cp2(CO)(µ-CO){µ-η 1 :η 2 -C(Me)C(Me)(SPh)CN(Me)2}], 7, respectively, probably via the intermediacy of the radical compounds 2c-d. The structures of 3-7 and 2c-d were elucidated by DFT calculations, and the isolated products were characterized by analytical and spectroscopic methods.

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Photochemical Alkyne Insertions into the Iron–Thiocarbonyl Bond of [Fe₂(CS)(CO)₃(Cp)₂]

Cited by 17 publications

References 70 publications

Bond Forming Reactions Involving Isocyanides at Diiron Complexes

Bond Forming Reactions Involving Isocyanides at Diiron Complexes

Constructing Organometallic Architectures from Aminoalkylidyne Diiron Complexes

DFT Mechanistic Insights into the Alkyne Insertion Reaction Affording Diiron μ-Vinyliminium Complexes and New Functionalization Pathways

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