Formation of Unusual Iridabenzene and Metallanaphthalene Containing Electron-Withdrawing Substituents

Paneque, Margarita; Posadas, Cristina M.; Poveda, Manuel L.; Rendón, Nuria; Salazar, Verónica; Oñate, Enrique; Mereiter, Kurt

doi:10.1021/ja035655p

Cited by 169 publications

(107 citation statements)

References 16 publications

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“…26 Jia, Lin, and co-workers synthesized the first metallanaphthalyne in 2007 (Scheme 18, right). 43 We discovered the synthesis of osmanaphthalene and osmanaphthalyne unexpectedly in 2009, when we studied the thermal and air stability of osmium hydride alkenylcarbyne 36.…”

Section: Osmanaphthalene and Osmanaphthalynementioning

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: Osmanaphthalene and Osmanaphthalynementioning

confidence: 99%

The Chemistry of Aromatic Osmacycles

et al. 2013

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“…Although the existence of higher homologues of metallabenzenes had only been inferred from their decomposition products and the comparable reactivity of the metallabenzene analogues, one of the most exciting developments in recent years is the isolation and characterization of iridanaphthalene 107 by Paneque et al [80] Synthesis of 107 begins by treating 108 with dimethyl acetylenedicarboxylate (DMAD), which yields isomeric iridacycloheptatrienes 109 and 110 (Scheme 28). [81] Even though no intermediates could be detected, these products are likely produced by initial insertion of one molecule of DMAD into one of the IrÀC aryl bonds.…”

Section: Iridanaphthalenementioning

confidence: 99%

“…If excess tBuOOH is added, then iridanaphthalene 107 is produced. [80] Conversion of 111 into 107 likely starts as a simple Baeyer-Villiger oxidation of the oxoacetyl group. The newly generated OÀC aliphatic bond in 112 can then be cleaved irreversibly to form 107.…”

Section: Iridanaphthalenementioning

confidence: 99%

“…Column chromatography of 107 on silica gel results in the destruction of its aromaticity and affords 113 (Scheme 28), [80] thus reminiscent of an internal "neutral" Jackson-Meisenheimer complex. [82] Hydrolysis of the carboxylate ligand in 107 would result in an intermediate hydroxyl complex, which likely undergoes intramolecular nucleophilic attack at the g-carbon atom to furnish 113.…”

Section: Iridanaphthalenementioning

confidence: 99%

“…[80] When Thorn and Hoffman first predicted the stability of metallabenzenes, it was suggested that because of the low-lying LUMO of the C 5 R 5 À fragment, p donors, especially those ortho and para to the metal, would be most suited for stabilizing the metallabenzene. [11] Although a number of metallabenzenes have been synthesized with p donors ortho to the metal fragment, [23,31] iridanaphthalene 107 and iridabenzenes 99, 105, and 115 are the first examples of metalla-aromatic species substituted with electron-withdrawing groups, namely CO 2 Me.…”

Section: Iridanaphthalenementioning

confidence: 99%

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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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