Does diatomic sulfur(S2) react as a free species?

Steliou, Kosta; Salama, Paul; Yu, Xiaoping

doi:10.1021/ja00030a048

Cited by 39 publications

(14 citation statements)

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“…Furthermore, the discrepancy in isolated yields for NDIs 2−5 (vide supra) suggests that cis-bis-thionated NDIs With this rationale, one can see that the final step(s) that generates product 7 requires desulfurization in a thermal cycloreversion reaction via extrusion of singlet diatomic sulfur 44,45 and subsequent H atoms transfer (from solvent) irrespective of the reactive intermediates: stepwise pathway (vinylic biradicaloid 1,2-dithiethane) or concerted pathway (hexacyclic disulfide intermediate). Steliou et al were the first to discover such a rearrangement of polycyclic 1,2-dithiethane, 46,47 which they inferred to be unstable until Nicolaou et al successfully synthesized and isolated dithiatopazine, the first example of 1,2-dithiethane. 48 Subsequently, we carried out thionation reactions with 3b using LR in toluene-d 8 under an inert atmosphere to determine the final reductive desulfurization step.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

A Naphtho-p-quinodimethane Exhibiting Baird’s (Anti)Aromaticity, Broken Symmetry, and Attractive Photoluminescence

Shokri

Manna

et al. 2017

J. Org. Chem.

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We report a novel reductive desulfurization reaction involving π-acidic naphthalene diimides (NDI) 1 using thionating agents such as Lawesson's reagent. Along with the expected thionated NDI derivatives 2-6, new heterocyclic naphtho-p-quinodimethane compounds 7 depicting broken/reduced symmetry were successfully isolated and fully characterized. Empirical studies and theoretical modeling suggest that 7 was formed via a six-membered ring oxathiaphosphenine intermediate rather than the usual four-membered ring oxathiaphosphetane of 2-6. Aside from the reduced symmetry in 7 as confirmed by single-crystal XRD analysis, we established that the ground state UV-vis absorption of 7 is red-shifted in comparison to the parent NDI 1. This result was expected in the case of thionated polycyclic diimides. However, unusual low energy transitions originate from Baird 4nπ aromaticity of compounds 7 in lieu of the intrinsic Hückel (4n + 2)π aromaticity as encountered in NDI 1. Moreover, complementary theoretical modeling results also corroborate this change in aromaticity of 7. Consequently, photophysical investigations show that, compared to parent NDI 1, 7 can easily access and emit from its T state with a phosphorescence (7a)* lifetime of τ = 395 μs at 77 K indicative of the formation of the corresponding "aromatic triplet" species according to the Baird's rule of aromaticity.

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Section: ■ Results and Discussionmentioning

confidence: 99%

A Naphtho-p-quinodimethane Exhibiting Baird’s (Anti)Aromaticity, Broken Symmetry, and Attractive Photoluminescence

Shokri

Manna

et al. 2017

J. Org. Chem.

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“…Comparison of the mass spectra of the synthesized compounds shows that all spectra reveal evidence of fragments with an m/z value of 44. Given the monomeric building blocks [19,20] CO-2 AA-MEG-AA-MEG C 16 [21,22] ). An exemplary mass spectrum for CO-6 is shown in Fig.…”

Section: Identification Of the Main Leachablesmentioning

confidence: 99%

Migrating components in a polyurethane laminating adhesive identified using gas chromatography/mass spectrometry

Athenstädt

Fünfrocken

Schmidt

2012

Rapid Comm Mass Spectrometry

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“…The open-chain precursor polymers can be cyclized in a polymer-analogous ring closure. A carbonyl olefination re-action, first described in 1992 by Steliou et al [9], was used with boron sulfide generated in situ. This synthetic variant was similarly applied in 1992 by Wang and Zhang [ 101 for the polymer-analogous generation of phenanthryl subunits in the main chain of poly(ether ketone)s with 2,2'dibenzoylbiphenyl sub-units and the high synthetic potential of this method demonstrated (quantitative conversion, no side-reactions).…”

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confidence: 99%

Conjugated all‐carbon ladder polymers: improved solubility and molecular weights

Chmil

Scherf

1997

Acta Polymerica

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Ladder structures that are composed exclusively of aromatic carbon centers have been the focus of theoretical calculations and diverse synthetic efforts for a long time.Polyacenes are a major interest in this area [ 11. Polyacenes are band molecules composed exclusively of annelated six-membered aromatic rings. Linear polyacenespoly[n]acenes -are, as polymers with low band-gap energy, poorly accessible as a result of their high reactivity (oxidation, dimerization) [2]. Hitherto only oligo[n]acenes up to hexa-and heptacene [3, 41 are known and characterized. Angular polyacenes are characterized, in comparison to poly[n]acene, by an enlarged energy gap (band gap), resulting from the diverse topology of the x-electron systems [5]. The extension of the longest linear [n]-acene segment in the angular band polymer is decisive for the specific value of the band-gap energy.A simple two-step synthesis for such an all-carbon ribbon was published recently [6]. The synthetic route represents a "classical" ladder polymer synthesis: a suitably substituted, open-chain precursor polymer is cyclized to a band structure in polymer-analogous fashion (Scheme 1). The

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Does diatomic sulfur(S2) react as a free species?

Abstract: Supplementary Material Available: Experimental procedures for 3c, 3d, 3g, 3h, 4c, 4d, 4g, 4h, 5b-d, 5g-i, 6c, 6e, 8m, 8n, 9m, 9n, 10m, 10 , 11m, lln, 12n, 13m, and 13n (9 pages). Ordering information is given on any current masthead page.

Cited by 39 publications

References 0 publications

A Naphtho-p-quinodimethane Exhibiting Baird’s (Anti)Aromaticity, Broken Symmetry, and Attractive Photoluminescence

A Naphtho-p-quinodimethane Exhibiting Baird’s (Anti)Aromaticity, Broken Symmetry, and Attractive Photoluminescence

Migrating components in a polyurethane laminating adhesive identified using gas chromatography/mass spectrometry

Conjugated all‐carbon ladder polymers: improved solubility and molecular weights

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