Actinide 2-metallabiphenylenes that satisfy Hückel’s rule

Pagano, Justin K.; Xie, Jing; Erickson, Karla A.; Cope, Stephen K.; Scott, Brian L.; Wu, Ruilian; Waterman, Rory; Morris, David E.; Yang, Ping; Gagliardi, Laura; Kiplinger, Jaqueline L.

doi:10.1038/s41586-020-2004-7

Cited by 52 publications

(45 citation statements)

References 57 publications

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“…As well‐known in Hückel theory and aromaticity, the side‐by‐side overlap between several p orbitals (π‐type orbital overlap, Scheme a‐Type I) makes phenyl rings or other similar conjugated organic cyclic compounds tend to exhibit planar structures. In addition to p orbitals, other types of orbitals, such as d orbitals in common transition metallacycles and f orbitals in U and Th metallacycles, may also overlap with p orbitals to realize electron delocalization. However, because d orbitals have different shapes and orientations, when they participate in a cyclic conjugated system and overlap with p orbitals, these orbitals may adopt disparate space positions (π‐type, Scheme a‐Type II; σ‐type, Scheme a‐Type III and Type IV) in order to maximize the degree of orbital overlap and achieve the utmost electron delocalization .…”

Section: Methodsmentioning

confidence: 99%

Butadienyl Diiron Complexes: Nonplanar Metalla‐Aromatics Involving σ‐Type Orbital Overlap

Zhong

Zhang

et al. 2020

Angew Chem Int Ed

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A new class of nonplanar metalla-aromatics, diiron complexes bridged by a 1,3-butadienyl dianionic ligand, were synthesized in high yields from dilithio reagents and two equivalents of FeBr 2. The complexes consist of two antiferromagnetically coupled high-spin Fe II centers, as revealed by magnetometry, Mçssbauer spectroscopy, and DFT calculations. Furthermore, experimental (X-ray structural analysis) and theoretical analyses (NICS, ICSS, AICD, MOs) suggest that the complexes are aromatic. Remarkably, this nonplanar metalla-aromaticity is achieved by an uncommon s-type overlap between the ligand p and metal d orbitals, in sharp contrast to the intensively studied planar aromatic systems featuring delocalized p-type bonding. Specifically, the s-type interaction between the two Fe 3d xz orbitals and the butadienyl p orbital results in the formation of a six-electron conjugated system and hence enables the aromatic character.

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Section: Methodsmentioning

confidence: 99%

Butadienyl Diiron Complexes: Nonplanar Metalla‐Aromatics Involving σ‐Type Orbital Overlap

Zhong

Zhang

et al. 2020

Angew Chem Int Ed

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“…[17] At the same time, the metallacyclopentadienes tabilization in the aromatic environment of ap orphyrin, is relevantt om etallacycle chemistry,g aining interest in context of unconventional aromaticity,i ncluding Mçbiusa romaticity,a nd the question of metal orbitals participation in delocalization of electrons. [18][19][20] The related keyword meso-metallaporphyrin,d escribes ad ifferent typeo fm acrocycles, nonaromatic structures based on four 1,2,3-triazole rings fixed with four meso-metal ions, forming ap orphyrin-like geometry. [21,22]…”

Section: Introductionmentioning

confidence: 99%

“…At the same time, the metallacyclopentadiene stabilization in the aromatic environment of a porphyrin, is relevant to metallacycle chemistry, gaining interest in context of unconventional aromaticity, including Möbius aromaticity, and the question of metal orbitals participation in delocalization of electrons [18–20] …”

Section: Introductionmentioning

confidence: 99%

Chemistry inside a Porphyrin Skeleton: Platinacyclopentadiene from Tellurophene

Pacholska‐Dudziak

Vetter

Góratowska

et al. 2020

Chemistry A European J

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Platinum(II) binds to 21,23-ditelluraporphyrinforming as ide-on complex,w hich can be easily transformed into an aromatic metallaporphyrin,t hat is, 21-platina-23-telluraporphyrin, with ap latinacyclopentadiene unit built in the porphyrin skeleton in place of one pyrrole ring. The central platinum(II) ion with aC CNTes quare-planarc oordination sphere can be oxidized to platinum(IV) by chlorine, bromine, methyl iodideora llyl chloridet oy ield octahedral complexes. All platinatelluraporphyrins show dynamic behaviori nvolving the platinum ion coordination sphere fluxionality and the porphyrin skeleton deformation, both in-plane and outof-plane, as demonstrated by 1 HNMR spectroscopy.

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“…Aromaticity is one of the most fundamental and interesting topics in organic chemistry. 1,2 Traditional π-aromaticity is characterized by π-electron delocalization in closed circuits of unsaturated compounds 3 and σ-aromaticity is characterized by the delocalization contributed by σ-electrons, which was first proposed by Dewar to explain the abnormal magnetic behavior of cyclopropane. 4 Subsequently, other systems, such as hydrogen clusters, 5 inorganic rings, 6 metal clusters [7][8][9][10] and metallacyclopropenes, [11][12][13][14] featuring delocalized σ-conjugation, were suggested to have σ-aromatic character.…”

Section: Introductionmentioning

confidence: 99%

Ring Contraction of Metallacyclobutadiene to Metallacyclopropene Driven by π- and σ-Aromaticity Relay

Zhuo

Liu

Ruan

et al. 2022

Preprint

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π-Aromaticity is an important driving force in directing the synthesis of aromatic compounds; in contrast, reactions induced by σ-aromaticity are uncommon. Herein, we report a strategy based on π- and σ-aromaticity relays to realize the first structurally defined ring contraction of metallacyclobutadiene to metallacyclopropene. This reaction involves the release of the π-antiaromaticity of metallacyclobutadiene in 2a to afford a π-aromatic intermediate (4A), followed by ring reclosure to generate σ-aromatic metallacyclopropene in 3a. The ring-opening-reclosing mechanism and versatile switching of the aromaticity of the metallacyclic species are supported by experimental results and theoretical calculations. This work demonstrates the importance of the synergistic effects of π- and σ-aromaticity as driving forces in reactions and sheds light on possible applications in other challenging transformations.

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Actinide 2-metallabiphenylenes that satisfy Hückel’s rule

Cited by 52 publications

References 57 publications

Butadienyl Diiron Complexes: Nonplanar Metalla‐Aromatics Involving σ‐Type Orbital Overlap

Butadienyl Diiron Complexes: Nonplanar Metalla‐Aromatics Involving σ‐Type Orbital Overlap

Chemistry inside a Porphyrin Skeleton: Platinacyclopentadiene from Tellurophene

Ring Contraction of Metallacyclobutadiene to Metallacyclopropene Driven by π- and σ-Aromaticity Relay

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