Selenium heterocycles. XXXI. Reaction of ethyl propiolate with 5-phenyl-2-thioxo-1,3-thiaselenole and 4-phenyl-2-thioxo-1,3-dithiole

Reaction of ethyl propiolate with 4-phenyl-2-thioxo-1,3-dithiole afforded 4-carbethoxy-2-thioxo-1,3-dithiole in high yield. Reaction of ethyl propiolate with 5-phenyl-2-thioxo-1,3-thiaselenole gave 4-carbethoxy-2-thioxo-1,3-thiaselenone (IX), 4-carbethoxy-2-selenoxo-1,3-dithiole (X) and 5-carbethoxy-2-thioxo-1,3-thiaselenole (XI). A possible mechanism for the formation of these compounds is given.     

Bis(1,3-dithiole-2-chalcogenones) and tetrathiafulvalenes in the synthesis of bridged tetrathiafulvalene-containing structures

Bis(1,3-dithiole-2-chalcogenones) in which the 1,3-dithiole fragments are linked through various bridging groups were synthesized by different methods. Some of these compounds were converted into substituted tetrathiafulvalenes with bridged 1,3-dithiole rings. The same structures were synthesized from preliminarily prepared symmetric tetrathiafulvalenes containing 2-cyanoethylsulfanyl groups in both 1,3-dithiole rings. Similar spacers were used to bridge two tetrathiafulvalene fragments. Syntheses of the involved initial compounds were described.     

Solution Structure of One-Electron Reduced and Oxidized Molecules with Twisted Donor and Acceptor Moieties

The solution structures of the radical anion and the radical cation of the donor-acceptor molecules 3,4-di(1,3-dithiol-2-ylidene)-4-phenylbut-1-ene-1,1-dicarbonitrile ( 1 ) and 3,4-di(1,3-dithiol-2-ylidene)-4-phenylbut-1-ene-1,1,2-tricarbonitrile ( 2 ) are discussed based on cyclovoltammetric and ESR/ENDOR measurements. It is shown that the spin population of the radical anions is limited to the di- and tricyanoethene moiety and the coplanar 1,3-dithiole at C(3), whereas that of the radical cations resides mainly inside the two 1,3-dithiole rings. The energies of the long-wave bands in the electronic-absorption spectra of 1 and 2 correspond to the differences between the oxidation and reduction potentials and thus point to a charge-transfer character of these transitions.     

Aza-analogues of extended tetrathiafulvalenes

The phosphoramidate-like reaction of 1,3-dithiole derived N-(diethoxyphosphinyl)hydrazones with formyl derivatives of 1,3-dithiole affords the longest aza-analogues of extended tetrathiafulvalenes with a polyenic spacer reported to date. Their structural and electrochemical properties are discussed.     

Novel Bis-Fused pi-Electron Donors for Organic Metals: 2-(1,3-Dithiol-2-ylidene)-5-(thiopyran-4-ylidene)-1,3,4,6-tetrathiapentalene

Bis-fused pi-electron donors composed of tetrathiafulvalene (TTF) and 2-(thiopyran-4-ylidene)-1,3-dithiole (TPDT), 2-(1,3-dithiol-2-ylidene)-5-(thiopyran-4-ylidene)-1,3,4,6-tetrathiapentalene (1a, TPDT-TTP), and its derivatives (1b-d, 2a-d) have been synthesized as donor components for organic conductors. An X-ray structure analysis of bis(methylthio)-1 (1c) revealed that the TPDT-TTP skeleton is almost planar except for the outer 1,3-dithiole ring, and that the crystal has a two-dimensional "theta-type" arrangement of molecules. The cyclic voltammograms of TPDT-TTPs exhibit four pairs of single-electron redox waves. The first oxidation potential (E(1)) of 1a (+0.37 V vs SCE, in PhCN) is comparable to that of TTF (+0.35 V) and is higher by 0.1 V than that of TPDT (+0.27 V). The observed substituent effect on E(1) values suggests that the first one-electron oxidation mainly occurs in the 2-(thiopyran-4-ylidene)-1,3-dithiole (TPDT) moiety. On the other hand, on-site coulombic repulsion estimated from the E(2) - E(1) value is lower than in TTF and TPDT. MNDO MO calculations reveal that all the sulfur atoms in the 1,3-dithiole rings have the same phase in the HOMO, a condition necessary for realization of effective transverse intermolecular interaction. The present donors have produced many charge-transfer complexes and cation radical salts showing relatively high conductivity (sigma(rt) = 10(-)(1)-10(1) S cm(-)(1)), several of which display metallic temperature dependence.     

New π-electron donors: Ethanediylidene-2,2′-bis(1,3-diselenole) and ethanediylidene-2-(1,3-dithiole)-2′-(1,3-diselenole)

This communication describes synthesis and electrochemical properties of new type of π-donors containing 1,3-diselenole ring, ethanediylidene-2,2′-bis(1,3-diselenole)(1a) and ethanediylidene-2-(1,3-dithiole)-2′-(1,3-diselenole)(2a). The conductivities of the charge-transfer complexes of these donors with tetracyanoquinodimethane (TCNQ) are also demonstrated.     

Preparation, structure and properties of novel 1,3-dithiol-2-ylidene derivatives containing bis(ethynylpyridine) units

1,3-Dithiol-2-ylidene derivatives containing bis(ethynylpyridine) units were synthesized using a Pd-catalyzed reaction of the corresponding dibromide. X-Ray crystal analysis revealed unique crystal structures depending on the aromatic groups. The absorption spectra and redox properties indicated intramolecular charge-transfer interactions between the 1,3-dithiole unit and the pyridyl parts.     

The Formation of Thioacylthioketenes by Flash Vacuum Pyrolysis of 1,2-Dithiole Derivatives

Abstract

The formation of thioacylthioketenes has been observed in Flash Vacuum Pyrolysis of various 1,2-dithiole derivatives. In some cases C₃S₂, 1,2-propadiene-1,3-dithione is formed too.     

Synthesis of 2,3-dimethyl-6-methoxycarbonyltetrathiafulvalene

A method is proposed for the synthesis of an unsymmetrically substituted tetrathiafulvalene with an acceptor substituent, viz., 2, 3-dimethyl-6-methoxycarbonyltetrathiafulvalene, from 2-tributylphosphonia-4-methoxycarbonyl-1,3-dithiole tetrafluoroborate.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 476–477, April, 1982.     

Oligomeric tetrathiafulvalenes: a new route toward conjugated TTF dimers and trimers

The synthesis of bis-TTF 1 and tris-TTF 2, linked by an ethenyl spacer, is described using new useful Wittig-type reagents with the introduction of phosphonate functionality on 1,3-dithiole and TTF frameworks. Electrochemical and spectroscopic studies show intramolecular electronic interactions between conjugated TTF units.     

Electrophilic substitution reactions of esters of 4,5-substituted 1,3-dithiol-2-ylideneacetic and 1,3-dithiol-2-ylidenemalonic acids

The electrophilic substitution reactions (with halogens, POCl₃ + DMF, diazonium salts, iodoso compounds) of both esters of 4,5-substituted 1,3-dithiol-2-ylideneacetic acids and sodium salts of monoethyl esters of the corresponding malonic acids can be used for the synthesis of 2-methylene-1,3-dithiole derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 898–900, July, 1989.     

Reaction of 1,3-diphenylbarbituric and 1,3 -diphenyl-2-thiobarbituric acids with diazotized sulfanilamides

The reaction of 1,3-diphenylbarbituric and 1,3-diphenyl-2-thiobarbituric acids with diazotized sulfaniiimides gives 1,3-diphenylalloxan and 1,3-diphenyl-2-thioalloxan phenylhydrazones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1276–1279, September, 1971.     

Synthesis and radical coupling of pyridine-bridged pi-extended tetrathiafulvalene (TTF)-type donors and push-pull analogues

A new family of pi-extended TTF analogues (3a-c) and D-pi-A chromophores (5a-c), in which the electroactive units (1,3-dithiole rings and 2,2-dicyanovinyl groups) are connected through a pyridine bridge with a meta substitution pattern, is reported. The redox behavior of these compounds has been investigated by cyclic voltammetry and theoretical calculations performed at the B3P86/6-31G** level. Unlike many pi-extended TTF derivatives, the 1,3-dithiole rings in compounds 3a-c do not behave independently and two oxidation processes are observed with an anodic separation ranging from 50 to 150 mV. Calculations show that electrons are equally extracted from both dithiole rings. A biradical structure is predicted for the dication state due to the near-degeneracy of the HOMO and HOMO - 1 orbitals. The presence of both donor (D) and acceptor (A) fragments in conjugates results in irreversible oxidation and reduction processes associated with the 1,3-dithiole ring and with the 2,2-dicyanovinyl moiety, respectively. An electrochemical-chemical-electrochemical (ECE) process takes place for all the compounds reported. The chemical process implies the dimerization of the radical cation for compounds 5 and the oligomerization of the biradical dication for compounds 3. The ECE process therefore generates new neutral dimeric (5) or oligomeric (3) species that incorporate the TTF vinylogue core.     

Structure of a carbenic precursor of tetrathiafulvalene coordinated to a triiron octacarbonyl cluster complex

The reaction between 1,3-dithiole 2-thione and Fe₂(CO)₉ gives a 1,3-dithiole-2-ylidenetriiron octacarbonyl cluster complex, (C₃H₂S₂)Fe₃(CO)₈S₂ the structure of which has been determined by X-ray diffraction.     

Decreased optical nonlinearities upon CF3 substitution on tricyanofuran acceptors

Replacement of the tricyanofuran (TCF) acceptor by its stronger analogue CF 3-TCF results in decreased second-order optical nonlinearities in merocyanines bearing a proaromatic 1,3-dithiole donor. The TCF-containing derivatives display exceptionally high mu beta values up to 31,000 x 10(-48) esu, unprecedented for 1,3-dithiole-based NLO-phores.     

Synthesis of 3-alkyl-2, 4, 6-triphenylpyridines and 1,3-diphenyl-4- and-2-azafluorenes

The previously unknown 3-alkyl-2,4,6-triphenylpyridines were obtained from 1-methyl-3-alkyl-2, 6-diphenyl-4-piperidones. It was established that a mixture of 1,3-diphenyl-4-azafluorene and 1,3-diphenyl-2-azafluorene is formed in the dehydrocyclization of 3-methyl-2,4,6-triphenylpyridine.     

An abrupt spin transition based on short S...S contacts in a novel Fe(II) complex whose ligand contains a 1,3-dithiole ring

The first preparation of an Fe(II) spin-crossover complex including a 1,3-dithiole ligand is reported. Crystal analyses of both the low- and the high-temperature phases reveal that short S...S contacts play a key role in an abrupt spin transition.     

Tetrathiafulvalene-acetylene scaffolding: new pi-electron systems for advanced materials

Novel extended tetrathiafulvalenes (TTFs) with hexa-2,4-diyne-1,6-diylidene spacers between the two 1,3-dithiole rings and laterally appended alkynyl moieties for one- and two-dimensional scaffolding were synthesised and investigated for their electronic properties.     

Reactions of 1-acyl-2-bromoacetylenes with dithiocarbamic acids

2-Acyl-2-bromoacetylenes react with dithiocarbamic acids in aprotic solvents (acetonitrile, chloroform, or ether) to give 5-acyl-2-diethylamino(heteryl)-1,3-dithiolium bromides, which on reaction with secondary amines (diethylamine or morpholine) undergo cleavage of the 1,3-dithiole ring to give 1-acyl-2-diethyl(morpholyl)dithiocarbamoyl-2-diethylamino(morpholyl)ethylenes. X-ray crystallographic studies on the product from one of these reactions has shown it to be 5-thenoyl-2-diethylamino-1,3-dithiolium bromide.Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, 664033 Irkutsk. A. V. Shubnikov Institute of Crystallography, Russian Academy of Sciences, 117331 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1850–1856, August, 1992.     

Mesoionic compounds—XIX: Mass spectral fragmentation patterns for some five-membered systems containing oxygen,nitrogen and sulfur

Mesoionic compounds of the s-triazole, 1,3,4-oxadiazole, 1,3,4-thiadiazole, 1,2,3-thiadiazole, 1,3-thiazole and 1,3-dithiole systems all underwent deep-seated decomposition on electron-impact to small stable ions, determined to a large extent by the nature of the peripheral heteroatoms and the exocyclic substituent. In some instances fragmentation most probably involved an open-chain isomer of the cyclic system.