Raison d'être of apparently antiaromatic 1,2-dithiin derivatives in nature

Ishida, Toshimasa; Oe, Sumio; Aihara, Jun‐ichi

doi:10.1016/s0166-1280(98)00434-5

Cited by 15 publications

(15 citation statements)

References 34 publications

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“…Dithiin was suggested to be the only antiaromatic molecule made in nature. 144 However, current density calculations at the B3LYP/def2-TZVP+D3 level using GIMIC show that the slightly nonplanar 1,2-dithiin (C 2 ) and 1,4-dithiin (C 2v ) molecules sustain ring currents of −0.8 and 3.2 nA/T, respectively. Thus, the two dithiin molecules are not antiaromatic.…”

Section: Aromaticity Of Planar Moleculesmentioning

confidence: 99%

Calculations of magnetically induced current densities: theory and applications

Sundholm

Fliegl

Berger

2016

WIREs Comput Mol Sci

323

543

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A review of computational studies of magnetically induced current density susceptibilities in molecules and their relation to experiments is presented. The history of the investigation of magnetically induced current densities and ring currents in molecules is briefly covered. The theoretical development of relativistic and nonrelativistic computational approaches for computing current densities in closed-shell and open-shell molecules is discussed and different state of the art methods to interpret calculated current densities are reviewed. Numerical integration approaches to assess global, semilocal, and local aromatic properties of multiring molecules are presented and demonstrated on free-base trans-porphyrin. We show that numerical integration of the current density combined with guiding visualization techniques of the current flow is a powerful tool for studies of the aromatic character of complicated molecular structures such as annelated aromatic and antiaromatic rings. Representative applications are reported illustrating the importance of careful current density studies for organic and inorganic chemistry. The applications include calculations of current densities and current strengths for aromatic, antiaromatic, and nonaromatic molecules of different kind. Current densities in spherical, cylindrical, tetrahedral, toroidal, and Möbius-twisted molecules are discussed. The aromatic character, current pathways, and current strengths of porphyrins are briefly highlighted. Aromatic properties of inorganic molecules are assessed based on current density calculations. Current strengths as a noninvasive tool to determine strengths of hydrogen bonds are discussed.

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Section: Aromaticity Of Planar Moleculesmentioning

confidence: 99%

Calculations of magnetically induced current densities: theory and applications

Sundholm

Fliegl

Berger

2016

WIREs Comput Mol Sci

323

543

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“…However, because of the intrinsic instability of the 1,2-dithiin ring, the synthesis and characterization of other derivatives have been quite limited until recently, when convenient synthetic routes for 1,2-dithiins were developed. , For example, Koreeda et al5a and Block et al5b independently succeeded in the total synthesis of thiaruburine A and B, respectively, by the use of versatile thiol-protecting groups. 1,2-Dithiins are also interesting molecules from a theoretical viewpoint: they have a twisted conformation that shows a bright reddish-orange color (λ max 410−490 nm) 1a despite the absence of a normal chromophore. For these reasons, the electronic structure of 1,2-dithiins has been the subject of both studies using theoretical calculations 7a and those using photoelectron spectroscopy 7b…”

Section: Introductionmentioning

confidence: 99%

“…1,2-Dithiins are also interesting molecules from a theoretical viewpoint: they have a twisted conformation that shows a bright reddish-orange color (λ max 410−490 nm) 1a despite the absence of a normal chromophore. For these reasons, the electronic structure of 1,2-dithiins has been the subject of both studies using theoretical calculations 7a and those using photoelectron spectroscopy 7b 1 …”

Section: Introductionmentioning

confidence: 99%

1,2-Dithiin Annelated with Bicyclo[2.2.2]octene Frameworks. One-Electron and Two-Electron Oxidations and Formation of a Novel 2,3,5,6-Tetrathiabicyclo[2.2.2]oct-7-ene Radical Cation with Remarkable Stability Owing to a Strong Transannular Interaction

2002

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A stable derivative of 1,2-dithiin annelated with bicyclo[2.2.2]octene frameworks 4 was synthesized as red crystals by the reaction of a dilithiated dimer of bicyclo[2.2.2]octene with elemental sulfur in 59% yield. The cyclic voltammetry of 4 in CH(2)Cl(2) at -78 degrees C showed two reversible oxidation waves at E(1/2) +0.18 V and +0.72 V versus Fc/Fc(+), indicating that the radical cation and dication of 4 are stable under these conditions. Upon chemical one-electron oxidation of 4 in a rather low concentration (4.0 x 10(-4) M) with a 1.5 equiv of SbCl(5) in CH(2)Cl(2), a radical cation 4.+ was formed, whose spin distribution was determined by ESR spectroscopy and by the results of theoretical calculations (UB3LYP/6-31G). The electronic absorption spectrum of 4.+ in CH(2)Cl(2) exhibited a maximum absorption at 428 nm (epsilon = 2.3 x 10(3)), which was hypsochromically shifted from that of neutral 4 (469 nm). When the radical cation 4.+ was produced in higher concentration (0.06 M) in CH(2)Cl(2), a disproportionation was found to take place to give a SbCl(6)(-) salt of remarkably stable radical cation 5.+ having a novel 2,3,5,6-tetrathiabicyclo[2.2.2]oct-7-ene structure. In the X-ray structure of 5.+SbCl(6)(-), the transannular distance (2.794(3) A) between the sulfur atoms was found to be less than the sum of the van der Waals radii of a sulfur atom (3.70 A), suggesting the existence of a bonding interaction between the two disulfide linkages. The theoretical calculations (UB3LYP/6-31G) suggested that this transannular interaction could be described as the resonance between the limiting structures, each of them having a two-center three-electron bond between two sulfur atoms belonging to two different disulfide linkages: thus, both the spin and positive charge are equally delocalized to the four sulfur atoms, causing a great stabilization of 5.+. On the other hand, the 1,2-dithiin radical cation 4.+ was found to readily react with triplet oxygen with subsequent rearrangement to give the 1,2-dithiolium derivative 6+ having a carboxyl group. Finally, the reaction of 4 with an excess amount of SbF(5) gave the corresponding dication 4(2+), which was found to be a 6pi aromatic system on the basis of the results of NMR measurement and theoretical calculations.

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“…1,2-Dithiins such as the thiarubrines can be found in plants and show extensive biological activity [4]. These compounds are also of interest to theoretical chemists because they adopt a non-planar twisted geometry and are antiaromatic [5][6][7]. Their high reactivity and structural instability have limited the synthesis and characterization of derivatives of these naturally occurring molecules [8,9].…”

Section: Introductionmentioning

confidence: 99%