New chiral organosulfur donors related to bis(ethylenedithio)tetrathiafulvalene

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.     

Examination of the charge-sensitive vibrational modes in bis(ethylenedithio)tetrathiafulvalene

We reinvestigated the two C=C stretching modes of the five-membered rings of ET (ET = bis(ethylenedithio)tetrathiafulvalene), namely, nu(2) (in-phase mode) and nu(27) (out-of-phase mode). The frequency of the nu(27) mode of ET(+) was corrected to be approximately 1400 cm(-1), which was identified from the polarized infrared reflectance spectra of (ET)(ClO(4)), (ET)(AuBr(2)Cl(2)), and the deuterium- or (13)C-substituted compounds of (ET)(AuBr(2)Cl(2)). It was clarified from DFT calculations that the frequency of the nu(27) mode of the flat ET(0) molecule was significantly different from that of the boat-shaped ET(0) molecule. We obtained the linear relationship between the frequency and the charge on the molecule, rho, for the flat ET molecule, which was shown to be nu(27)(rho) = 1398 + 140(1 - rho) cm(-1). The frequency shift due to oxidation is remarkably larger than that reported in previous studies. The fractional charges of several ET salts in a charge-ordered state can be successfully estimated by applying this relationship. Therefore, the nu(27) mode is an efficient probe to detect rho in the charge-transfer salts of ET. Similarly, a linear relationship for the nu(2) mode was obtained as nu(2)(rho) = 1447 + 120(1 - rho). This relationship was successfully applied to the charge-poor molecule of theta-type ET salts in the charge-ordered state but could not be applied to the charge-rich molecule. This discrepancy was semiquantitatively explained by the hybridization between the nu(2) and nu(3) modes.     

Facile synthesis of novel functionalized bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) derivatives

An improved and efficient synthetic route to four functionalized bis(ethylenedithio)-tetrathiafulvalene (BEDT-TTF) derivatives 2-5 is reported. Tetrathiolate 1 was readily prepared from 2,2'-bis(1,3,4,6-tetrathiapentalen-5-one) under carefully controlled conditions. Subsequent reaction of 1 with selected primary alkyl halides affords new functionalized BEDT-TTF derivatives in good yields.     

Synthesis of bis(ethylenedithio)tetrathiafulvalene derivatives with metal ion ligating centres

The syntheses of eight derivatives of BEDT-TTF (ET) containing pyridine, 2,2′-bipyridine or 2,4′-pyridylpyrimidine binding sites on a side chain are reported, for use in the preparation of organic/inorganic hybrid materials. The intermediate hydroxyethyl derivative of BEDT-TTF is prepared in an efficient five-step procedure.     

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

Syntheses of enantiopure organosulfur donors by three different strategies requiring only four-six steps are reported. The key step involves either double substitution of an enantiopure cyclic sulfate ester by a dithiolate, attachment of a chiral diol as a ketal, or completely diastereoselective cycloaddition of 1,3-dithiole-2,4,5-trithione to an enantiopure alkene.     

Synthesis and properties of a hexadecyl derivative of bis(ethylenedithio)tetrathiafulvalene (hexadecyl BEDT-TTF)

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 131–132, January, 1990.     

Synthetic procedure for various selenium-containing electron donors of the bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) type

Six selenium variants of BEDT-TTF have been successfully synthesized by a newly developed synthetic method that involves a combination of two key reactions for the construction of two kinds of heterocyclic rings: the first is a one-pot formation of 1,3-dichalcogenole-2-chalcogenones from a common starting material, THP-protected 2-(ethynylthio)ethanol, leading to the inner five-membered rings, and the other is the annelation of the outer six-membered heterocyclic ring onto the inner ring by an intramolecular transalkylation reaction on a chalcogen atom. This method turned out to be widely applicable to the syntheses of the electron donors of bis(ethylenedithio)- and bis(ethyleneselenothio)-substituted types. However, synthetic attempts to form analogous donors of the bis(ethylenediseleno)-substituted type from THP-protected 2-(ethynylseleno)ethanol were unsuccessful. This is attributable to the predominance of side-reactions via a seleniranium (episelenonium) salt over the desired six-membered ring formation by transalkylation via a seleninium salt.     

Photochemistry of electron donor-acceptor complexes of the bis(fulvalene) dicobalt mono- and dications

Addition of carbon tetrachloride or chloroform to acetonitrile solutions of the bis(fulvalene)dicobalt monocation results in the appearance of new absorption features which are attributed to formation of electron donor-acceptor complexes. The association constants of these complexes aer 2.36 /mole fraction (carbon tetrachloride) and 2.74 /mole fraction (chloroform). Excitation in the absorption bands of the donor-acceptor complexes results in oxidation of the monocation to the dication with high quantum yields. A donor-acceptor complex is also formed when sodium tetraphenylborate is added to acetonitrile solutions of the bis(fulvalene)dicobalt dication. Spectroscopic determination of the association constant of the dication with tetraphenylborate yields a value of 26.3 /mole fraction. Excitation of the absorption bands of the ion-pair results in high quantum yields for formation of the bis(fulvalene) dicobalt monocation. Biphenyl is found in photolyzed solutions as a byproduct of the oxidation of the tetraphenylborate anion.     

Synthesis of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) derivatives functionalised with two, four or eight hydroxyl groups

Short synthetic routes to a range of BEDT-TTF derivatives functionalised with two, four or eight hydroxyl groups are reported, of interest because of their potential for introducing hydrogen bonding between donor and anion into their radical cation salts. The cycloaddition of 1,3-dithiole-2,4,5-trithione with alkenes to construct 5,6-dihydro-1,3-dithiolo[4,5-b]1,4-dithiin-2-thiones is a key step, with homo- or hetero-coupling procedures and O-deprotection completing the syntheses. The first synthesis of a single diastereomer of tetrakis(hydroxymethyl)BEDT-TTF, the cis,trans product, was achieved by careful choice of O-protecting groups to facilitate separation of homo- and hetero-coupled products. Cyclisation of the trithione with enantiopure 1R,2R,5R,6R-bis(O,O-isopropylidene)hex-3-ene-1,2,5,6-tetrol (from D-mannitol) gave two separable diastereomeric thiones, which can be transformed to enantiomeric BEDT-TTF derivatives with four or eight hydroxyl groups.     

Incommensurate nature of the multilayered molecular ferromagnetic metals based on bis(ethylenedithio)tetrathiafulvalene and bimetallic oxalate complexes

The salt [ET]x[MnRh(ox)(3)].CH(2)Cl(2) (x = 2.526(1)) has been obtained and characterized. This paramagnetic metal is essentially isostructural to the ferromagnetic metal [ET]y[MnCr(ox)(3)].CH(2)Cl(2) (y approximately equal to 3) and provides a definite answer on the origin of the structural disorder present on such systems. As in the ferromagnetic analogue, this material shows high electrical conductivity at room temperature (13 S.cm(-1)) and metallic behavior.     

A new radical cation salt bis(ethylenedithio)tetrathiafulvalene with [Pt(NO2)4]2− anion: Synthesis, structure, and conductivity

A radical cation salt based on bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) containing the [Pt(NO₂)₄]^2? anion was synthesized for the first time. The crystal and molecular structure of this salt, (BEDT-TTF)₂Pt(NO₂)₄, was established by X-ray diffraction analysis. The crystal structure consists of radical cation BEDT-TTF layers between which planar-square anions [Pt(NO₂)₄]^2? are located. The layers are formed by BEDT-TTF stacks built of dimers. The interplanar distances within the dimers and between them are 3.41 and 3.96 Å, respectively. The distribution of the bond lengths and bond angles in BEDT-TTF corresponds to the charge of the cation +1. The room-temperature conductivity of (BEDT-TTF)₂Pt(NO₂)₄ is 3·10^?3 Ω^?1 cm^?1, and the temperature dependence of the conductivity exhibits the semiconducting character.     

Sterically hindered mono- and bis(2,5-diaryloxazoles) containing biphenyl systems

The condensation of hydrochloric salts of -aminomethyl aryl ketones with diphenic anhydride or with the diacid chloride of diphenic acid and subsequent cyclodehydration of the condensation products formed give sterically hindered mono- and bis(2, 5-diaryloxazoles) containing the biphenyl system. The spectroluminescent properties of these compounds were studied. Comparison of the absorption spectra of 2,2-di(5-phenyloxazolyl-2)biphenyl and 2,5-diphenyloxazole indicates the complete lack of conjugation between the diphenyloxazole fragments, their independent behavior, and their retention of the spatial configuration of 2,5-diphenyloxazole. 2,2-Di(5-phenyloxazolyl-2)biphenyl has a large Stokes shift. Steric hindrance is also found in 2-carboxy-2-(5-phenyloxazolyl-2)biphenyl molecules.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 184–188, February, 1985.     

Crystal structure of the simple radical-cation salt bis(propylenedithio)tetrathiafulvalene tribromomercurate, (BPDT-TTF)HgBr3

Institute of Chemical Physics, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 31, No. 5, pp. 31–38, September–October, 1990.     

Optical properties of bis(pyrazino)tetrathiafulvalene salts

The optical reflectance and absorption spectra of (BPTTF)₂BF₄[where BPTTF is bis(pyrazino) tetrathiafulvalene] and similar salts are reported for a wide spectral region.