Conversions of Osmabenzyne and Isoosmabenzene

Zhao, Qianyi; Zhu, Jun; Huang, Zi‐Ao; Zou, Yingping; Xia, Haiping

doi:10.1002/chem.201201558

Cited by 45 publications

(27 citation statements)

References 91 publications

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“…The structural data indicate that 3 a is the first iso‐metallapyridinium with form IV (Scheme ), which is closely related to the iso‐metallabenzenes. It is worth noting that the Os1‐C1‐C2 angle (150.5(6)°) deviates considerably from linearity and is even smaller than those of reported six‐membered iso‐metallabenzenes (155.1(8)° and 158.5(3)° and iso‐metallabenzenones (152.7(5)° and 151.1(2)°) . This is further support that resonance form 3 A is an important contribution to the overall structure of complex 3 a .…”

Section: Resultssupporting

confidence: 69%

“…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 . We have recently verified the existence of the first five‐membered metallacycles that contain a metal–vinylidene moiety ( III ) and the conversion of these compounds to their analogous six‐membered metallacycles ( II ) .…”

Section: Introductionmentioning

confidence: 83%

See 1 more Smart Citation

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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Section: Resultssupporting

confidence: 69%

Section: Introductionmentioning

confidence: 83%

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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“…[48] In contrast, on treatment of the cationic osmabenzyne 36 with strong nucleophiles, addition to the carbon para to osmium occurs giving the stable isoosmabenzenes, 37. [153] The regioselectivity of these reactions is controlled by both electronic and steric factors.…”

Section: Metallabenzynesmentioning

confidence: 99%

Recent Advances in Metallaaromatic Chemistry

Frogley

Wright

2017

Chemistry A European J

145

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Metallaaromatics can be broadly defined as aromatic compounds in which one of the ring atoms is a transition metal. The metallabenzenes are one important class of these compounds that has undergone extensive study recently. Closely related species such as fused-ring metallabenzenes, heterometallabenzenes, π-coordinated metallabenzenes and metallabenzynes have also attracted considerable attention. Although many metallaaromatics can be considered as metalla-analogues of classic organic aromatic compounds, this is not always the case. Recent seminal studies have shown that metallapentalenes and metallapentalynes, which are metalla-analogues of the anti-aromatic compounds pentalene and pentalyne, are in fact aromatic and highly stable. Very unusual spiro-metallaaromatic compounds have also recently been isolated. In this concepts article, key features of all these intriguing metallaaromatic compounds are discussed with reference to the structural, spectroscopic, reactivity and theoretical studies that have been undertaken. These compounds continue to generate much interest, not only because of the contributions they make to fundamental chemical understanding, but also because of the promise of possible practical applications.

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“…33 We then further expanded the organic substrate to HCt CCH(OEt) 2 and obtained an osmabenzyne 33 unexpectedly (Scheme 12). 34 The reaction started with a similar [3 þ 3] cycloaddition process to an intermediate isoosmabenzene 32, which then eliminated an ethoxyl group to give a stable osmabenzyne 33. Isoosmabenzene 32 was stable in solution for several hours, thus allowing in situ NMR monitoring of the transformation from 32 to 33.…”

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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Conversions of Osmabenzyne and Isoosmabenzene

Cited by 45 publications

References 91 publications

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

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

Recent Advances in Metallaaromatic Chemistry

The Chemistry of Aromatic Osmacycles

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