Preparation and Characterization of an Isometallabenzene with the Structure of a 1,2,4-Cyclohexatriene

Barrio, Pilar; Esteruelas, Miguel A.; Oñate, Enrique

doi:10.1021/ja039633e

Cited by 110 publications

(62 citation statements)

References 35 publications

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“…5,8,9 Esteruelas et al prepared the first isometallabenzene (Scheme 12, right). 32 In 2011, we capitalized on an unprecedented formal [3 þ 3] cycloaddition reaction between osmium hydride vinylidene 31 and alkynols to prepare stable isoosmabenzenes 31aÀc (Scheme 12). 33 We then further expanded the organic substrate to HCt CCH(OEt) 2 and obtained an osmabenzyne 33 unexpectedly (Scheme 12).…”

Section: Osmabenzenementioning

confidence: 99%

The Chemistry of Aromatic Osmacycles

et al. 2013

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A romatic compounds, such as benzene and its derivatives, porphyrins, fullerenes, carbon nanotubes, and graphene, have numerous applications in biomedicine, materials science, energy science, and environmental science. Metalla-aromatics are analogues of conventional organic aromatic molecules in which one of the (hydro)carbon segments is formally replaced by an isolobal transition-metal fragment. Researchers have studied these transition-metalcontaining aromatic molecules for the past three decades, particularly the synthesis and reactivity of metallabenzenes. Another focus has been the preparation and characterization of other metalla-aromatics such as metallafurans, metallapyridines, metallabenzynes, and more. Despite significant advances, remaining challenges in this field include the limited number of convenient and versatile synthetic methods to construct stable and fully characterized metalla-aromatics, and the relative shortage of new topologies.To address these challenges, we have developed new methods for preparing metalla-aromatics, especially those possessing new topologies. Our synthetic efforts have led to a large family of closely related metalla-aromatics known as aromatic osmacycles. This Account summarizes the synthesis and reactivity of these compounds, with a focus on features that are different from those of compounds developed by other groups. These osmacycles can be synthesized from simple precursors under mild conditions. Using these efficient methods, we have synthesized aromatic osmacycles such as osmabenzene, osmabenzyne, isoosmabenzene, osmafuran, and osmanaphthalene. Furthermore, these methods have also created a series of new topologies, such as osmabenzothiazole and osmapyridyne. Our studies of the reactivity of these osma-aromatics revealed unprecedented reaction patterns, and we demonstrated the interconversion of several osmacycles.Like other metalla-aromatics, osma-aromatics have spectroscopic features of aromaticity, such as ring planarity and the characteristic bond lengths between a single and double bond, but the osma-aromatics we have prepared also exhibit good stability towards air, water, and heat. Indeed, some seemingly unstable species proved stable, and their stability made it possible to study their optical, electrochemical, and magnetic properties. The stability of these compouds results from their aromaticity and the phosphonium substituents on the aromatic plane: most of our osma-aromatics carry at least one phosphonium group. The phosphonium group offers stability via both electronic and steric mechanisms. The phosphonium acts as an electron reservoir, allowing the circulation of electron pairs along metallacycles and lowering the electron density of the aromatic rings. Meanwhile, the bulky phosphonium groups surrounding the aromatic metallacycle prevent most reactions that could decompose the skeleton.

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Section: Osmabenzenementioning

confidence: 99%

The Chemistry of Aromatic Osmacycles

et al. 2013

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“…In the presence of excess NaCl, the decomposition process is controlled and produces isoosmabenzene 40 in 64 % yield. [48] The mechanism involved in producing 40 probably starts with migration of the a-alkenyl carbon atom to the a-carbyne carbon atom. Next, the b-alkynyl carbon atom couples with the b-alkenyl carbon atom.…”

Section: Isoosmabenzenementioning

confidence: 99%

Recent Advances in Metallabenzene Chemistry

2006

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Research into aromatic metallacycles, though discussed in the literature over the last quarter century, has undergone a major expansion since 2000. A wide variety of new metallabenzenes, encompassing new synthetic methods and new metal centers, is now available. New aromatic metallacycle topologies (iridanaphthalene, osmabenzynes) have been isolated and characterized. The first metallabenzene valence isomers (iridabenzvalenes, rhodabenzvalenes) and constitutional isomers (isoosmabenzenes) are now known. This review discusses the synthesis, chemistry, and physical properties of these intriguing aromatic compounds.

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“…However, the linear geometry of vinylidene–metal structures makes incorporation of the units into small‐ring systems particularly difficult. The first reported cyclic vinylidene–metal complexes ( I , Scheme ) were prepared by Esteruelas and co‐workers in 2004, and were described as iso‐metallabenzenes in the literature. Other examples of iso‐metallabenzenes have been synthesized by formal [3+3] cycloaddition reactions .…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Cyclic Vinylidene Complexes and Azavinylidene Complexes by Formal [4+2] Cyclization Reactions

Chen

Huang

Lü

et al. 2016

Chemistry A European J

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Reactions of the hydrido-butenylcarbyne complex [OsHCl2(≡CC(PPh3)=CHEt)(PPh3)2]BF4 (1) with nitriles RC≡N (R=2-cyclopropyl-2-oxopropyl, 3-amino-2-oxobutyl) lead to six-membered cyclic vinylidene complexes 3 and azavinylidene complexes 4, that is, iso-osmapyridiniums. Treatment of 1 with excess 2-formylbenzonitrile at reflux temperature in CHCl3 in the presence of air produces a fused osmapyridinium 8, which is first oxidized to the tricyclic iso-osmapyridinium derivative 7, then to iso-osmapyridinium 9, which contains a fused naphthalenone fragment. The conversion of iso-osmapyridinium 9 (with a vinylidene segment) to the iso-osmapyridinium compounds 10 and 11 (with azavinylidene segments) was achieved in the presence of a hydrogen halide, such as HCl or HI. The molecular structures of the complexes synthesized were confirmed by X-ray studies. Moreover, the aromatic stabilization energy and nucleus-independent chemical-shift values of the osmapyridiniums and the strain in the iso-osmapyridinium rings were investigated by DFT calculations.

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Preparation and Characterization of an Isometallabenzene with the Structure of a 1,2,4-Cyclohexatriene

Cited by 110 publications

References 35 publications

The Chemistry of Aromatic Osmacycles

The Chemistry of Aromatic Osmacycles

Recent Advances in Metallabenzene Chemistry

Synthesis of Cyclic Vinylidene Complexes and Azavinylidene Complexes by Formal [4+2] Cyclization Reactions

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