Synthetic strategies to chiral organosulfur donors related to bis(ethylenedithio)tetrathiafulvalene

Griffiths, Jon-Paul; Nie, Hui; Brown, R.James; Day, Peter; Wallis, John D.

doi:10.1039/b502437d

Cited by 37 publications

(28 citation statements)

References 64 publications

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“…9 The X-ray crystal structure of 25 indicated strain at the quarternary carbon atom at the fusion with the dithiin ring, and it is probably this factor in the oxo compound which facilitates ring opening with triethyl phosphite. A sensible step would be to make the material without the methyl group at the strained centre, for which apopinene 27 is required as starting material.…”

Section: Synthesis Of Donors 13-16mentioning

confidence: 99%

“…3-4, 4 BEDT-TTF derivatives with stereogenic carbon atoms in the molecular skeleton, e.g. 5-8 [5][6][7][8][9][10] , EDT-TTF derivatives containing a chiral oxazoline group such as 9, 11 and an enantioenriched donor 10 containing a stereogenic sulfur atom. 12 A small number of radical cation salts of enantiopure donors have now been characterised and in two cases, (6) 2 PF 6 and (9) 2 AsF 6 , a comparison made between enantiomeric and racemic materials.…”

Section: Introductionmentioning

confidence: 99%

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New chiral organosulfur donors related to bis(ethylenedithio)tetrathiafulvalene

et al. 2010

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Abstract. Six new enantiopure chiral organosulfur donors, with structures related to BEDT-TTF, have been synthesised for use in the preparation of organic metals, starting either by double nucleophilic substitutions on the bis-mesylate of 2R,4R-pentane-2,4-diol or by a cycloaddition with subsequent elimination of acetic acid on the enol acetate of (+)-nopinone. Crystal structures of some of their radical cation triiodides salts and TCNQ complexes are reported. 2 IntroductionThe radical cation salts and charge transfer molecular complexes of TTF 1 and BEDT-TTF 2 show a wide range of electrical behaviour, and have found use in a range of systems including metallic systems, semiconductors and low-temperature superconductors. Here we report the synthesis of a group of novel chiral organosulfur donors, 11-16, in which chirality is provided by one or more hydrocarbon groupings. The structures of products from initial experiments to form charge transfer complexes are also described. 4 Discussion Synthesis of 11 and 12Electrocrystallisation of the enantiopure donor (S,S,S,S)-tetramethylBEDT-TTF 5 has given a series of radical cation salts, but their crystal structures were pseudocentrosymmetric, with the methyl groups adopting equatorial orientations. 6 However, we reasoned that insertion of a methylene group between each pair of stereogenic centres to give 11 would provide a more promising system. The outer seven-membered rings of donor 11 would be expected to adopt chair conformations and give two possible molecular conformations, A and B (Fig. 1), in analogy with the structures of 17-19. 17 The trans orientation of the methyl groups on the propylene bridge would force one into an axial position and the other into an equatorial position.Molecules in conformation B could be envisaged to stack in a helix. The synthesis of donor 11 started with the cyclisation of the dithiolate 20, prepared in three steps from carbon disulfide, 18 with the bis-mesylate of R,R-pentane-5 2,4-diol (Scheme 1). The first mesylate group is substituted by reaction in methanol at room temperature, but it was necessary to replace the methanol with THF and heat to reflux to complete the cyclisation to give the thione 21 in 45% yield. The thione was converted to oxo compound 22 using mercuric acetate in quantitative yield, and this was then homocoupled in refluxing trimethyl phosphite over 24 hours to give 11 in 75% yield. Cross-coupling, under similar conditions, of oxo compound 22 with a three-fold excess of the unsubstituted thione 23 yielded the cross-coupled donor 12 in 22% yield after chromatography. The low yield of 12 is a consequence of the faster homocoupling of thione 23 to give BEDT-TTF. Scheme 1The molecular structures of donors 11 and 12 were determined by X-ray crystallography. For both donors the seven-membered rings adopt chair conformations with one methyl group in an axial position and one in an equatorial position. For the homocoupled donor 11 (Fig. 2) the structure of the organosulfur system deviates very strongly from plana...

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Section: Synthesis Of Donors 13-16mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

New chiral organosulfur donors related to bis(ethylenedithio)tetrathiafulvalene

et al. 2010

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“…Nevertheless, as mentioned earlier, no such evidence has been provided so far in bulk conductors, including the TTF-based materials, although the influence of chirality on the conducting properties of TTF conductors has been indirectly expressed through the modulation of the structural disorder in a few series of conducting radical cation salts based on chiral TTFoxazoline 17,18 or TM-BEDT-TTF donors 19 , in which the enantiopure materials were more conducting than the racemic ones because of the structural disorder present in the latter. Compared with the relatively large number of chiral TTF precursors 16,20 , only a few examples of derived conducting materials have been described, such as those based on TM-BEDT-TTF 13,19,21 dimethyl-bis(ethylenedithio)-TTF (DM-BEDT-TTF) 22,23 , or TTF-oxazoline 17,18 . Moreover, complete series of conducting salts containing both enantiomers and the racemic forms, in order to compare their conducting properties, are even more scarce [17][18][19] , and in all of them the enantiomeric pairs crystallize within the same space group, although there is in principle the possibility that enantiomers crystallize in one of the 11 enantiomorphic space groups, which remains, however, a relatively rare event.…”

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confidence: 99%

Electrical magnetochiral anisotropy in a bulk chiral molecular conductor

et al. 2014

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So far, no effect of chirality on the electrical properties of bulk chiral conductors has been observed. Introduction of chiral information in tetrathiafulvalene precursors represents a powerful strategy towards the preparation of crystalline materials in which the combination of chirality and conducting properties might allow the observation of the electrical magnetochiral anisotropy effect. Here we report the synthesis by electrocrystallization of both enantiomers of a bulk chiral organic conductor based on an enantiopure tetrathiafulvalene derivative. The enantiomeric salts crystallize in enantiomorphic hexagonal space groups. Single crystal resistivity measurements show metallic behaviour for the enantiopure salts down to 40 K, in agreement with band structure calculations. We describe here the first experimental evidence of electrical magnetochiral anisotropy in these crystals, confirming the chiral character of charge transport in our molecular materials.

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“…We have already reported the total diastereoselectivity of the reactions of the trithione 24 with enantiopure alkenes (-)-α-pinene, (-)-β-pinene and (+)-2-carene. 11 Encouraged by this, we extended the study to the structurally less complex enantiopure alkene 54 (Scheme 5) which has two stereocentres adjacent to the double bond and four protected hydroxyl groups and which is readily prepared from Dmannitol. 36 Trithione 24 reacted with this alkene to give major (31%) and minor (5%) 1:1 addition products which were assigned structures 55 and 56 respectively, based on the X-ray crystal structure of the minor isomer 56 (Fig.…”

Section: Preparation Of Hydroxyethyl-et 19mentioning

confidence: 99%

“…16 New ET derivatives containing metal binding sites such as 10 with potential for preparing bifunctional materials with magnetic metal ions, [17][18] and an enantiopure donor 11 derived from (-)-β-pinene have recently been prepared. 11 Cross coupling reactions have been utilised to prepare substituted derivatives of the ethylenedithio-TTF system 12. 19 Furthermore, substituted derivatives of selenium containing donors, such as BETS 20 13, may soon become available following developments in synthetic approaches 21 which will be of interest since some BETS Here we describe the synthesis of a range of ET donors carrying between one and eight hydroxyl groups.…”

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confidence: 99%