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Regularities of the property changes in the compounds EuLnCuS3 (Ln = La-Lu)
This work contains the results of complex experimental research of the compounds EuLnCuS3 (Ln = La-Lu) enhanced by the DFT calculations. It is aimed at the data replenishment with particular attention to the revelation of regularities in the property changes, in order to extend the potential applicability of the materials of the selected chemical class. The ab initio calculations of the fundamental vibrational modes of the crystal structures were in good agreement with experimental results. The wavenumbers and types of the modes were determined, and the degree of the ion participation in the modes was also estimated. The elastic properties of the compounds were calculated. The compounds were found out to be IR-transparent in the range of 4000–400 cm–1. The estimated microhardness of the compounds is in the range of 2.68–3.60 GPa. According to the DSC data, the reversible polymorphous transitions were manifested in the compounds EuLnCuS3 (Ln = Sm, Gd-Lu): for EuSmCuS3 Tα?β = 1437 K, ΔНα?β = 7.0 kJ·mol-1, Tβ?γ = 1453 K, ΔНβ?γ = 2.6 kJ·mol-1; for EuTbCuS3 Tα?β = 1478 K, ΔНα?β = 1.6 kJ·mol-1, Tβ?γ = 1516 K, ΔНβ?γ = 0.9 kJ·mol-1, Tγ?δ = 1548 K, ΔНγ?δ = 1.6 kJ·mol-1; for EuTmCuS3 Tα?β = 1543 K, Tβ?γ = 1593 K, Tγ?δ = 1620 K; for EuYbCuS3 Tα?β = 1513 K, Tβ?γ = 1564 K, Tγ?δ = 1594 K; for EuLuCuS3 Tα?β = 1549 K, Tβ?γ = 1601 K, Tγ?δ = 1628 K. In the EuLnCuS3 series, the transition into either ferro- or ferrimagnetic states occurred in the narrow temperature range from 2 to 5 K. The tetrad effect in the changes of incongruent melting temperature and microhardness conditioned on rLn3+ as well as influencing of phenomenon of crystallochemical contraction were observed. For delimiting between space groups Cmcm and Pnma in the compounds ALnCuS3, the use of the tolerance factor t’ = IR(A)·IR(C) + a×IR(B)2 was verified.
Ruseikina, Anna V.,Chernyshev, Vladimir A.,Velikanov, Dmitriy A.,Aleksandrovsky, Aleksandr S.,Shestakov, Nikolay P.,Molokeev, Maxim S.,Grigoriev, Maxim V.,Andreev, Oleg V.,Garmonov, Alexander A.,Matigorov, Alexey V.,Melnikova, Ludmila V.,Kislitsyn, Anatoliy A.,Volkova, Svetlana S.
(2021/05/04)

Evolution of Structural, Thermal, Optical, and Vibrational Properties of Sc2S3, ScCuS2, and BaScCuS3 Semiconductors
In the present work, we report on the synthesis of Sc2S3, ScCuS2 and BaScCuS3 powders using a method based on oxides sulfidation and modification of their properties. The crystal structures and morphology of samples are verified by XRD and SEM techniques. Thermal stability has been studied by DTA which has revealed that Sc2S3 decomposes to ScS through melting at 1877 K. ScCuS2 and BaScCuS3 melt incongruently at temperatures of 1618 K and 1535 K, respectively. The electronic structure calculations show that the investigated compounds are semiconductors with indirect band gap (Eg). According to the diffuse reflection spectroscopy, Sc2S3, ScCuS2 and BaScCuS3 are wide-bandgap semiconductors featured the Eg values of 2.53 eV, 2.05 eV and 2.06 eV, respectively. The band gap decreases with the introduction of copper (I) and barium cations into the crystal structure of the compounds. Variation of local structure has been verified by Raman and infrared spectroscopy. The calculated vibrational modes of ScCuS2 correspond to CuS4 and Sc?S layer vibrations, even though ScS6 octahedra-like structural units can be found in the structure.
Aleksandrovsky, Aleksandr S.,Andreev, Oleg V.,Azarapin, Nikita O.,Leonidov, Ivan I.,Maximov, Nikolai G.,Oreshonkov, Aleksandr S.,Razumkova, Illaria A.,Shestakov, Nikolai P.
p. 3355 - 3366
(2021/08/23)

Synthesis of copper(i) cyclic (alkyl)(amino)carbene complexes with potentially bidentate N^N, N^S and S^S ligands for efficient white photoluminescence
The reaction of (Me2L)CuCl with either NaS2CX [X = OEt, NEt2 or carbazolate (Cz)] or with 1,3-diarylguanidine, 1,3-diarylformamidine or thioacetaniline in the presence of KOtBu affords the corresponding S- or N-bound copper complexes (Me2L)Cu(S^S) 1-3, (Me2L)Cu(N^N) 4/5 and (Me2L)Cu(N^S) 6 (aryl = 2,6-diisopropylphenyl; Me2L = 2,6-bis(isopropyl)phenyl-3,3,5,5-tetramethyl-2-pyrrolidinylidene). The crystal structure of (Me2L)Cu(S2CCz) (3) confirmed the three-coordinate geometry with S^S chelation and perpendicular orientation of the carbene and S^S ligands. On heating 3 cleanly eliminates CS2 and forms (Me2L)CuCz. The N-bound complexes show strongly distorted T-shaped (4) or undistorted linear (5) geometries. On excitation with UV light the S-bound complexes proved non-emissive, while the guanidinato and formamidinato complexes are strongly phosphorescent, with excited state lifetimes in the range of 11-24 μs in the solid state. The conformationally flexible formamidinato complex 5 shows intense green-white phosphorescence with a solid-state quantum yield of >96%.
Romanov, Alexander S.,Chotard, Florian,Rashid, Jahan,Bochmann, Manfred
p. 15445 - 15454
(2019/11/03)

Synthesis and Upconversion Luminescence in LaF3:Yb3+, Ho3+, GdF3: Yb3+, Tm3+ and YF3:Yb3+, Er3+ obtained from Sulfide Precursors
Rare earth fluorides are mainly obtained from aqueous solutions of oxygen-containing precursors. Probably, this method is simple and efficient, however, oxygen may partially be retained in the fluoride structure. We offer an alternative method: obtaining fluorides and solid solutions based on them from an oxygen-free precursor. As starting materials, we choose sulfides of rare-earth elements and solid solutions based on them. The fluorination is carried out by exposure to hydrofluoric acid of various concentrations. The transmission electron microscopy images revealed the different morphologies of the products, which depend on the concentration of the fluorinating component (HF) and the host element. The solid solution particle size varied from 30–35 nm in the case of GdF3:Yb3+, Tm3+ (4 % HF) to larger structures with dimensions exceeding 200 nm, such as that for LaF3:Yb3+, Ho3+ (40 % HF). The thermal characteristics, such as the temperatures of the transitions and melting and enthalpies, were determined for the solid solutions and simple fluorides. Applicability of the materials obtained as biological luminescent markers was tested on the example of upconversion luminescence, and good upconversion properties were detected.
Razumkova, Illariia A.,Denisenko, Yuriy G.,Boyko, Andrey N.,Ikonnikov, Denis A.,Aleksandrovsky, Aleksandr S.,Azarapin, Nikita O.,Andreev, Oleg V.
p. 1393 - 1401
(2020/01/02)

PROCESS FOR CONVERSION OF DIMETHYL SULFIDE TO METHYL MERCAPTAN
Disclosed herein are systems and processes involving the catalyzed cleavage reaction of dimethyl sulfide to methyl mercaptan. The catalyzed cleavage reaction can be a standalone system or process, or can be integrated with a methyl mercaptan production plant.
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Paragraph 0086-0089

(2018/03/09)

Y2S3 – Y2O3 phase diagram and the enthalpies of phase transitions
A phase diagram of the Y2S3-Y2O3, system has been defined from 1000 K to melts for the first time; the enthalpies of phase transitions in the systems have been determined. The monoclinic phase δ-Y2S3 (P21/m, a = 1.7523(8) nm, b = 0.4010(9) nm, с = 1.0170(7) nm, β = 98.60(6)°; microhardness H = 411 ± 7 HV) transforms at 1716 ± 7 K to the unquenchable high-temperature phase ξ-Y2S3, ΔН = 29 ± 6 J/g (7.9 KJ/mol) as determined by DSC. The quenching can't latch the Y2S3-phase. The melting point of Y2S3 is 1888 ± 7 K; ΔН = 150 ± 28 J/g (41.1 KJ/mol). Y2OS2 has a monoclinic structure (P21/c, а = 0.8256(8) nm, b = 0.6879(8) nm, с = 0.6848(8) nm, β = 99.52(6), Н = 491 ± 13 HV) and melts incongruently at 1790 ± 8 K, ΔН = 190 ± 45 J/g (52 KJ/mol) by the scheme Y2OS2 ? Y2O2S + L (16 mol% Y2O3). Y2O2S has a hexagonal structure (a = 0.3784(5) nm, c= 0.6584(4) nm, Н = 654 ± 7 HV). Its congruent melting temperature is 2350 ± 40 K as determined by visual polythermal analysis (VPTA). The eutectic formed by Y2S3 and Y2OS2 phases has the composition 14.0 ± 0.5 mol% Y2O3 (0.58Y2S3 + 0.42Y2OS2) and melting temperature 1770 ± 6 K; ΔН = 215 ± 39 J/g. Between Y2O2S and Y2O3 phases, there is a eutectic with the coordinates 80 ± 1 mol% Y2O3 (0.6Y2O2S + 0.4Y2O3) and melting temperature 2150 ± 35 K (VPTA).
Andreev,Pimneva
p. 24 - 29
(2018/04/17)

METHOD FOR PREPARING METHYL MERCAPTAN
The present invention relates to a method for preparing methyl mercaptan, in batches or continuously, preferably continuously, said method including at least the following steps: a) reacting at least one hydrocarbon feedstock in the presence of hydrogen sulphide (H2S) and optionally sulphur (S) such as to form carbon disulphide (CS2) and hydrogen (H2); b) reacting said carbon disulphide (CS2) by hydrogenation in the presence of said hydrogen (H2) obtained in step a) such as to form methyl mercaptan (CH3SH), hydrogen sulphide (H2S) and possibly hydrogen (H2); c) optionally recirculating said hydrogen sulphide (H2S) formed during step b) to step a); and d) recovering the methyl mercaptan.
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Paragraph 0107-0110

(2017/06/27)

Photochemical properties and structure characterization of (BiO)2CO3 nanowires doped with alkaline-earth metal ions
The photoluminescence (PL) properties and photocatalytic activities of pure (BiO)2CO3 nanowires and (BiO)2CO3 nanowires doped with alkaline-earth metal ions (Mg2+, Ca2+, and Sr2+
Cui, Kuixin,He, Yuehui,Guo, Yujiao,Jin, Shengming
p. 111 - 118
(2017/03/02)

Investigation of pyramidal inversion of nitrogen atom in carbamate and thiocarbamate ions formed at the reaction of СО2, СOS, CS2 with 2-aminoethanol
Dynamic NMR was applied to measuring the value ΔG≠ characterizing the height of the barrier to the pyramidal inversion of the nitrogen atom in carbamate and thiocarbamate anions formed at the reaction of 2-aminoethanol with CO2 and COS. The refinement was introduced in formerly suggested cyclic structures of anions containing an intramolecular hydrogen bond NHO(S), which contradicted the found large values of the barrier of inversion (ΔG≠ ～ 70 kJ mol–1). The hydrogen bond in the cyclic anions of carbamates and thiocarbamates is two-electron and three-center. Analogous cyclic structure with a multicenter hydrogen bond does not form in the case of dithiocarbamate anion that is the product of 2-aminoethanol reaction with CS2.
Talsi,Evdokimov
p. 1630 - 1636
(2017/12/29)

Cadmium Bis(phenyldithiocarbamate) as a Nanocrystal Shell-Growth Precursor
Cadmium bis(phenyldithiocarbamate) [Cd(PTC)2] is prepared and structurally characterized. The compound crystallizes in the monoclinic space group P21/n. A one-dimensional polymeric structure is adopted in the solid state, having bridging PTC ligands and 6-coordinate pseudo-octahedral Cd atoms. The compound is soluble in DMSO, THF, and DMF and insoluble in EtOH, MeOH, CHCl3, CH2Cl2, and toluene. {CdSe[n-octylamine]0.53} quantum belts and Cd(PTC)2 react to deposit epitaxial CdS shells on the nanocrystals. With an excess of Cd(PTC)2, the resulting thick shells contain spiny CdS nodules grown in the Stranski-Krastanov mode. Stoichiometric control affords smooth, monolayer CdS shells. A base-catalyzed reaction pathway is elucidated for the conversion of Cd(PTC)2 to CdS, which includes phenylisothiocyanate and aniline as intermediates, and 1,3-diphenylthiourea as a final product.
Morrison, Calynn E.,Wang, Fudong,Rath, Nigam P.,Wieliczka, Brian M.,Loomis, Richard A.,Buhro, William E.
p. 12920 - 12929
(2017/11/15)

Kinetic Insights into Hydrogen Sulfide Delivery from Caged-Carbonyl Sulfide Isomeric Donor Platforms
Hydrogen sulfide (H2S) is a biologically important small gaseous molecule that exhibits promising protective effects against a variety of physiological and pathological processes. To investigate the expanding roles of H2S in biology, researchers often use H2S donors to mimic enzymatic H2S synthesis or to provide increased H2S levels under specific circumstances. Aligned with the need for new broad and easily modifiable platforms for H2S donation, we report here the preparation and H2S release kinetics from a series of isomeric caged-carbonyl sulfide (COS) compounds, including thiocarbamates, thiocarbonates, and dithiocarbonates, all of which release COS that is quickly converted to H2S by the ubiquitous enzyme carbonic anhydrase. Each donor is designed to release COS/H2S after the activation of a trigger by activation by hydrogen peroxide (H2O2). In addition to providing a broad palette of new, H2O2-responsive donor motifs, we also demonstrate the H2O2 dose-dependent COS/H2S release from each donor core, establish that release profiles can be modified by structural modifications, and compare COS/H2S release rates and efficiencies from isomeric core structures. Supporting our experimental investigations, we also provide computational insights into the potential energy surfaces for COS/H2S release from each platform. In addition, we also report initial investigations into dithiocarbamate cores, which release H2S directly upon H2O2-mediated activation. As a whole, the insights on COS/H2S release gained from these investigations provide a foundation for the expansion of the emerging area of responsive COS/H2S donor systems.
Zhao, Yu,Henthorn, Hillary A.,Pluth, Michael D.
supporting information
p. 16365 - 16376
(2017/11/22)

Copper(I)-mediated direct trifluoromethylthiolation of allylic halides with elemental sulfur and (trifluoromethyl)trimethylsilane
Abstract A new method has been developed for the copper-mediated trifluoromethylthiolation of allylic halides by using potassium fluoride, elemental sulfur, and (trifluoromethyl)trimethylsilane in anhydrous N,N-dimethylformamide. This protocol provides facile access to a variety of allylic trifluoromethyl thioethers in moderate to good yields under mild, ligand-free reaction conditions.
Li, Jue,Wang, Peiqiang,Xie, Fei-Fei,Yang, Xi-Gang,Song, Xiao-Nan,Chen, Wei-Dong,Ren, Jiangmeng,Zeng, Bu-Bing
supporting information
p. 3568 - 3571
(2015/06/08)

Influence of sulfuretted temperature on the luminescent properties of Y2O2S:Eu3+, Mg2+, Ti4+ nanoarrays by EDTA complexing sol-gel template method
Y2O3:Eu3+, Mg2+, Ti 4+ nanotube arrays were prepared by sol-gel template method using EDTA (Ethylene Diamine Tetraacetic Acid) as complexing agent to serve as precursor. Long-lasting phosphors Y2
Wang, Lei,Dong, Jie,Huang, Ping,Cui, Cai E.
p. 330 - 335
(2014/03/21)

Photocatalytic carbon disulfide production via charge transfer quenching of quantum dots
Carbon disulfide, a potentially therapeutic small molecule, is generated via oxidative cleavage of 1,1-dithiooxalate (DTO) photosensitized by CdSe quantum dots (QDs). Irradiation of DTO-QD conjugates leads to λirr independent photooxidation with a quantum yield of ～4% in aerated pH 9 buffer solution that drops sharply in deaerated solution. Excess DTO is similarly decomposed, indicating labile exchange at the QD surfaces and a photocatalytic cycle. Analogous photoreaction occurs with the O-tert-butyl ester tBuDTO in nonaqueous media. We propose that oxidation is initiated by hole transfer from photoexcited QD to surface DTO and that these substrates are a promising class of photocleavable ligands for modifying QD surface coordination.
Bernt, Christopher M.,Burks, Peter T.,Demartino, Anthony W.,Pierri, Agustin E.,Levy, Elizabeth S.,Zigler, David F.,Ford, Peter C.
supporting information
p. 2192 - 2195
(2014/03/21)

Room temperature spontaneous conversion of OCS to CO2 on the anatase TiO2 surface
High-resolution FT-IR spectroscopy combined with quantum chemical calculations was used to study the chemistry of OCS-disproportionation over the reduced surface of isotopically labelled, nanocrystalline TiO2. Analysis of the isotopic composition of the product gases has revealed that the reaction involves solely OCS molecules from the gas-phase. Using quantum chemical calculations we propose a plausible mechanistic scenario, in which two reduced Ti3+ centres mediate the reaction of the adsorbed OCS molecules.
Civi?, Svatopluk,Ferus, Martin,?poner, Judit E.,?poner, Jirí,Kavan, Ladislav,Zukalová, Markéta
p. 7712 - 7715
(2014/07/08)

Sulfur as a selective 'soft' oxidant for catalytic methane conversion probed by experiment and theory
Developing efficient catalytic processes to convert methane into useful feedstocks relies critically upon devising new coupling processes that use abundant, thermodynamically 'mild' oxidants together with selective catalysts. We report here on elemental sulfur as a promising 'soft' oxidant for selective methane conversion to ethylene over MoS 2, RuS 2, TiS 2, PdS and Pd/ZrO 2 catalysts. Experiments and density functional theory reveal that methane conversion is directly correlated with surface metal-sulfur bond strengths. Surfaces with weakly bound sulfur are more basic and activate methane C-H bonds more readily. In contrast, experimental and theoretical selectivities scale inversely with surface metal-sulfur bond strengths, and surfaces with the strongest metal-sulfur bonds afford the highest ethylene selectivities. High CH 4 /S ratios, short contact times and the provision of a support maximizes the coupling of CH x intermediates and selectivity to ethylene, because these conditions yield surfaces with stronger metal-sulfur bonding (for example, Pd 16 S 7), which suppresses the over-oxidation of methane.
Zhu, Qingjun,Wegener, Staci L.,Xie, Chao,Uche, Obioma,Neurock, Matthew,Marks, Tobin J.
p. 104 - 109
(2013/08/24)

Nickel-heterocumulene complexes stabilized by trimethylphosphine: Synthesis, characterization and catalytic application in organozinc coupling with CS2
The reactivity of Ni(PMe3)4 with CO2, CS2 and SCNPh was studied. Although CO2 is structurally homologous compound with CS2 and SCNPh, its reactivity with Ni(PMe3)4 shows a different result with those of CS 2 and SCNPh. Reactions of Ni(PMe3)4 with carbon disulfide and phenyl isothiocyanate in THF give the tetrahedral coordinate complexes (Me3P)3Ni(η2-CS2) (1) and (Me3P)3Ni(η2-SCNPh) (3), characterized by standard spectroscopic methods and X-ray diffraction. Nickel(0) complexes 1 and 3 are stabilized by the strong donor ligand PMe3. In the case of CO2, attempts to isolate the expected nickel(0) complex (Me 3P)3Ni(η2-CO2) (4) proved to be unsuccessful. To further extend the utility of our nickel catalysts, the catalytic coupling of organozinc bearing different functionalities with CS 2 was explored. With 10 mol% of 1 as the catalyst, MeZnMe, EtZnEt and PhZnBr coupled with CS2 to form the corresponding methyl dithiocarboxylate following esterfication of the initial products.
Huang, Ning,Li, Xiaoyan,Xu, Wengang,Sun, Hongjian
p. 446 - 451
(2013/02/25)

Metal-free oxidative trifluoromethylthiolation of terminal alkynes with CF3SiMe3 and elemental sulfur
A metal-free oxidative trifluoromethyl-thiolation of terminal alkynes using readily available CF3SiMe3 and elemental sulfur at room temperature has been developed. This reaction provides an efficient and convenient method for the preparation of alkynyl trifluoromethyl sulfides bearing a wide range of functional groups. Preliminary investigation revealed that elemental sulfur instead of air acted as the oxidant.
Chen, Chao,Chu, Lingling,Qing, Feng-Ling
supporting information; experimental part
p. 12454 - 12457
(2012/09/05)

Complexes of the gilman reagent with double bonds across the π-σ Continuum
By using rapid injection NMR at low temperatures, a variety of π-complexes of lithium dimethylcuprate(I) with C-C, C-N, and C-S double bonds have been prepared and characterized. Complexation is generally accompanied by large upfield changes in chemical shift for the substrate carbon atoms bonded to copper. In the case of α,β-unsaturated carbonyl compounds, the changes for the carbonyl carbons are much smaller in magnitude, which is consistent with the usual η2 representation of these structures. It is possible for one ligand to displace another, and in this way an order of stability can be elucidated. Treatment of selected π-complexes with chlorosilanes or cyanosilanes gives CuIII intermediates.
Bertz, Steven H.,Cope, Stephen K.,Hardin, Richard A.,Murphy, Michael D.,Ogle, Craig A.,Smith, David T.,Thomas, Andy A.,Whaley, Tara N.
p. 7827 - 7838
(2013/01/16)

SULFUR TRANSFER REAGENTS FOR OLIGONUCLEOTIDE SYNTHESIS
The use of N-formamidino-5-amino-3H-1,2,4-dithiazole-3-thiones, 5-phenyl-3H-1,2,4-dithiazole-3-thiones, and derivatives thereof as novel, efficient sulfur-transfer reagents is disclosed. Sulfur transfer from these reagents to compounds containing a P(III) atom (e.g., triphenylphosphine, 5′-O-DMT-thymidine 2-cyanoethyl-(N,N-diisopropyl)phosphoramidite, and 5′-O-DMT-3′-O-levulinyl dithymidilyl 2-cyanoethyl phosphite), was studied in solution by 31P NMR and HPLC. The sulfur transfer from title compounds was also studied in the solid-phase synthesis of oligonucleotide phosphorothioates by phosphoramidite methods. In this application, the efficiency of the sulfur transfer reaction for 2′-deoxyoligonucleotides was better than 99.5%. The novel sulfurizing agents are synthesized, at low cost, using simple chemical methods. As opposed to many sulfur transfer reagents known in the prior art such as 1,2-benzodithiol-3-one-1,1-dioxide (Beaucage reagent) and 5-ethoxy-3H-1,2,4-dithiazole-2-one (EDIT), the sulfurizing agents disclosed herein are highly stable in solution, which increases their practical and commercial value.
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(2011/06/24)

PROCESS FOR CONTINUOUSLY PREPARING METHYL MERCAPTAN FROM CARBON COMPOUNDS, SULFUR AND HYDROGEN
The invention relates to a process for continuously preparing methyl mercaptan by reacting a mixture comprising carbon compounds with sulfur and hydrogen, wherein the carbon disulfide and hydrogen sulfide compounds which form are subsequently converted to methyl mercaptan.
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Page/Page column 4-5

(2011/02/18)

Solvent, salt and high pressure effects on the rate and equilibrium constants for the formation of tri-n-butylphosphoniumdithiocarboxylate
Solvent, salt and high pressure effects on the rate and equilibrium constants for the formation of tri-n-butylphosphoniumdithiocarboxylate at 298.2 K are reported. This equilibrium is shifted to the phosphobetaine in polar solvents, salt solutions and under high external pressure. The reaction volume changes dramatically on going from less polar diethyl ether (-69 cm3 mol-1) and tetrahydrofurane (THF) (-66 cm3 mol -1), to more polar acetonitrile (-39 cm3 mol-1) and acetone (-38 cm3 mol-1). Copyright
Iskhakova, Gulnara G.,Kiselev, Vladimir D.,Van Eldik, Rudi,Zahl, Achim,Shihab, Mehdi S.,Konovalov, Alexander I.
scheme or table
p. 360 - 365
(2011/11/14)

UV-induced transformations of matrix-isolated 1,3,4-thiadiazole-2-thiones
Monomers of 5-mercapto-1,3,4-thiadiazole-2-thione (bismuthiol) were studied using an experimental matrix-isolation technique as well as by carrying out theoretical quantum chemical calculations. The calculations, performed using the quadratic configuration interaction method with single and double excitations (QCISD)/6-31++G(d,p)//DFT(B3LYP)/ 6-311 ++G(2d,p), predict that the thione-thiol tautomer of bismuthiol should be significantly (by more than 19 kJ mol-1) more stable than other tautomeric forms. Accordingly, only the signatures of the thione-thiol tautomer were observed in the FT-IR spectrum of bismuthiol, recorded directly after deposition of an Ar matrix. UV (l> 320 nm) irradiation induced the conversion of the thione-thiol tautomer into the dithiol form. Analogous investigations were carried out for two related compounds: 5-methyl-1,3,4-thiadiazole-2-thione and 5-methylthio-1,3,4-thiadiazole-2-thione. For these two species, only the thione tautomeric forms were observed after deposition of Ar matrices. These tautomers were predicted (by QCISD calculations) to be more stable (by at least 19kJmol-1) than other tautomeric forms. Upon UV irradiation, the most stable thione forms of these compounds were transformed into the corresponding thiol tautomers. Direct observation of the thione! thiol phototautomeric processes provides a clear proof that intramolecular proton transfer reaction can occur in molecules, such as bismuthiol, in spite of the increased NH...S distance, in comparison to other phototautomerizing species studied so far. All the isomers of the studied compounds (substrates and products of the photoreactions) were identified by comparison of their IR spectra with the spectra calculated at the DFT(B3LYP)/6-311 ++G(2d,p) level of theory for possible isomeric structures. Copyright
Rostkowska, Hanna,Lapinski, Leszek,Nowak, Maciej J.
experimental part
p. 56 - 66
(2010/07/08)

Dimethyl disulfide conversion into dimethyl sulfide in the presence of sulfidized catalysts
The conversion of dimethyl disulfide in the presence of various supported sulfidized metal-containing catalysts at atmospheric pressure and T = 150-350°C was studied. Sulfidized transition metals supported onto aluminum oxide were more active than catalysts based on a carbon support, silicon dioxide, amorphous aluminosilicate, and zeolite ZSM-5. The most active catalyst was 10% Co/Al2O3 prepared with the use of cobalt acetate as an active component precursor and treated with a mixture of hydrogen sulfide with hydrogen at T = 400°C. From kinetic data, it follows that all of the reaction products were formed simultaneously at a temperature of 200°C, whereas a consecutive reaction scheme took place at higher temperatures. In the presence of a sulfidized alumina-cobalt catalyst, the output of dimethyl sulfide was higher than that reached with the use of other well-known catalysts.
Mashkina,Khairulina
experimental part
p. 724 - 730
(2011/02/16)

PROCESS FOR PRODUCING ANTIAGING AGENT, VULCANIZATION ACCELERATOR OR MODIFIED NATURAL RUBBER BY MEANS OF MICROORGANISM OR PLANT
An object of the present invention is to provide processes for producing an antiaging agent, a vulcanization accelerator and a modified natural rubber, which are environmentally friendly and capable of making provision against a decrease of petroleum resources in the future. An antiaging agent, a vulcanization accelerator or a modified natural rubber is produced by a method comprising: converting glucose into benzoic acid or a benzoic acid derivative by a microorganism or extracting benzoic acid or a benzoic acid derivative from a plant; and converting the obtained benzoic acid or benzoic acid derivative into aniline or an aniline derivative.
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Page/Page column 3

(2009/12/24)

The crystal structure of thallium(I) trithiocarbonate, Tl 2CS3
Thallium trithiocarbonate, T12CS3, was prepared by the reaction of Na2CS3 with T1NO3 in aqueous solution. T12CS3 has a low solubility and is precipitated as an orange powder. DSC
Beck, Johannes,Benz, Sebastian
p. 962 - 965
(2009/10/16)

Mechanisms of acid decomposition of dithiocarbamates. 5. Piperidyl dithiocarbamate and analogues
(Chemical Equation Presented) In this work, the acid cleavage at 25°C in 20% v/v aqueous ethanol of a series of analogues of piperidine dithiocarbamate X(C2H4)2NCS2 - (X = CH2, CHCH3, NH, NCH3, S, O) was studied. The pH-rate profiles were obtained in the range of Ho -5 and pH 5. They all presented a dumbell shaped curve with a plateau from which the pH-independent first-order rate constant ko (or the specific acid catalysis kH) was calculated, in addition to the acid dissociation constant of the free (pKa) and conjugate acid (pK+) species of the DTC. LFERs of the kinetically determined pKa and pK+ versus pKN (pKa of parent amine) were used to characterize the reactive species and the structure of the transition state of the rate-determining step. For X = CH2, CH3CH the values of kH agree with those of alkDTCs in the strong base region of the Bronsted plot of log kH versus pKN where the transition state is close to a zwitterion formed by intramolecular water-catalyzed S-to-N proton transfer of the dithiocarbamic acid. However, when X = NH, CH3N, O, S, the reactive species is the DTC anion, which is as reactive as an arylDTC, and similarly, the pK+ values correspond to a parent amine that is about 3-4 pK units more basic. The solvent isotope effect indicated that the acid decomposition of these dithiocarbamate anions is specifically catalyzed by a Hydron anchimerically assisted by the heteroatom through a boat conformation.
Humeres, Eduardo,Byung, Sun Lee,Debacher, Nito Angelo
scheme or table
p. 7189 - 7196
(2009/05/09)

Infrared absorption of gaseous ClCS detected with time-resolved Fourier-transform spectroscopy
A transient infrared absorption spectrum of gaseous ClCS was detected with a step-scan Fourier-transform spectrometer coupled with a multipass absorption cell. ClCS was produced upon irradiating a flowing mixture of Cl2 CS and N2 or C O2 with a KrF excimer laser at 248 nm. A transient band in the region of 1160-1220 cm-1, which diminished on prolonged reaction, is assigned to the C-S stretching (1) mode of ClCS. Calculations with density-functional theory (B3P86 and B3LYP/aug-cc-pVTZ) predict the geometry, vibrational wave numbers, and rotational parameters of ClCS. Therotational contour of the spectrum of ClCS simulated based on predicted rotational parameters agrees satisfactorily with experimental observati on; from spectral simulation, the band origin is determined to be at 1194.4 cm-1. Reaction kinetics involving ClCS, CS, and C S2 are discussed.
Chu, Li-Kang,Han, Hui-Ling,Lee, Yuan-Pern
p. 1 - 7
(2009/02/03)

Synthesis and reactivity of the ruthenium(II) dithiocarbonate complex [Ru(κ2-S2C=O)(dppm)2] (dppm = bis(diphenylphosphino)methane)
Reaction of cis-[RuCl2(dppm)2] (dppm = bis(diphenylphosphino)methane) with CS2 and NaOH yields the first ruthenium dithiocarbonate complex, [Ru(κ2-S2C=O) (dppm)2]. Protonation with tetrafluoroboric acid affords the xanthate complex [Ru(κ2-S2COH)(dppm)2]BF 4 in a reversible manner, suggesting that this may be an intermediate in dithiocarbonate formation. [Ru(κ2-S2C=O)(dppm) 2] reacts with methyl iodide or [Me3O]BF4 to give [Ru(κ2-S2COMe)(dppm)2]+, also obtained from the reaction of cis-[RuCl2(dppm)2] with CS2 and NaOMe. Two modifications of [Ru(κ2-S 2C=O)-(dppm)2] were examined crystallographically and the structure of [Ru(κ2-S2COMe)(dppm) 2]BF4 and a new modification of cis-[RuCl 2(dppm)2] are also reported.
Wilton-Ely, James D. E. T.,Solanki, Dina,Hogarth, Graeme
p. 5210 - 5214
(2008/10/09)

FTIR studies of O(3P) atom reactions with CSe2, SCSe, and OCSe
The overall rate coefficients of the reactions of CSe2, SCSe, and OCSe with O(3P) atom have been determined to be kCSe2 = (1.4 ± 0.2) × 10-10 cm3 molecule-1 s-1, kSCSe = (2.8 ± 0.3) × 10-11 cm3 molecule-1 s-1, and kOCSe = (2-4 ± 0.3) × 10-11 cm3 molecule -1 s-1 at 301-303 K using Fourier transform infrared (FTIR) absorption spectroscopy. The measurements have been accomplished by calibrating against the literature value of the rate coefficient for O( 3P) with CS2 (4 × 10-12 cm3 molecule-1s-1). A product channel giving OCSe in 32.0 ± 4.2% yield has been found for the O + CSe2 reaction. Although CO was also detected, its generation could be attributed to subsequent reactions of OCSe with O atoms. The corresponding reaction for O + SCSe gives OCS and OCSe as observable products, with their yields given as 32.2 ± 4.5 and 30.2 ± 3.3%, respectively. Computational studies using UB3LYP/aug-cc-PVTZ methods have been used particularly to determine the reaction pathways for the channels in which OCS or OCSe is produced.
Li, Shuping,Chwee, Tsz Sian,Fan, Wai Yip
p. 11815 - 11822
(2008/10/09)

High-temperature synthesis of thiophene from bis(2-chloroethyl) sulfide
Gas-phase reaction of bis(2-chloroethyl) sulfide (Yperite) with acetylene at 550-700°C leads to formation of thiophene in 45% yield, the conversion of the initial sulfide being complete. The yield of thiophene reaches 63-68% in the thermolysis of a mixture of acetylene, bis(2-chloroethyl) sulfide, and lower organic disulfides.
Voronkov,Levanova,Sukhomazova,Russavskaya,Deryagina,Korchevin
p. 891 - 893
(2007/10/03)

Process for the preparation of organic disulfides
The invention relates to a process for the preparation of organic disulfides by oxidation of mercaptans with sulfur dissolved in an organic disulfide using an amine as catalyst, where the mercaptans are used as “crude mercaptan stream” from a reaction of alcohols with hydrogen sulfide over a catalyst suitable for mercaptan synthesis. Furthermore, the invention relates to the use of the organic disulfides for the preparation of alkanesulfonic acids.
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(2008/06/13)

Thermal degradation processes in polysulfide copolymers investigated by direct pyrolysis mass spectrometry and flash pyrolysis - Gas chromatography/mass spectrometry
This is the first report on the analysis of random block polysulfide copolymers containing different amounts of repeating units in the copolymer backbone, which has been studied by direct pyrolysis mass spectrometry (DPMS) and by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The homopolymers such as poly(ethylene sulfide) (PES), poly(styrene sulfide) (PSS), and two random copolymers, viz., poly(ethylene sulfidex-co-styrene sulfidey) [copolymer I (x = y = 0.5) and copolymer II (x = 0.74, y = 0.26)] were investigated by both DPMS and Py-GC/MS (except copolymer II) techniques. In the case of copolymer I, the thermal degradation products of SE1, SE2, S2, and S2E (S = styrene sulfide, E = ethylene sulfide) were detected in DPMS, whereas the formation of SE1 and SE2 were observed by Py-GC/MS technique. However, for copolymer II, SE3 was also found along with SE1, SE2, S2, and S2E in DPMS. The formation of additional product (SE3) observed in copolymer II could be due to an increase in the block length formed during copolymerization. Further, a comparative study on thermal degradation of PES, poly(ethylene disulfide) (PEDS), and poly(ethylene tetrasulfide) (PETS) were investigated by Py-GC/MS. The pyrolysis products detected by both DPMS and Py-GC/MS indicates that the thermal decomposition of these polymers yield cyclic sulfides through an intramolecular exchange or by backbiting processes. The linear products with thiol and vinyl groups were also observed by Py-GC/MS along with the cyclic products via carbon hydrogen transfer reaction.
Sundarrajan,Surianarayanan,Srinivasan,Kishore
p. 3331 - 3337
(2007/10/03)

Transient puffs of trace organic emissions from a batch-fed waste propellant incinerator
Emissions data have been obtained from a waste propellant incinerator. The incinerator is a dual fixed hearth, controlled air incinerator equipped with acid gas and particulate scrubbing. Puffing has been evident in this waste propellant incinerator by spikes in the CO concentration. Transient puffs of organics may travel down the combustion chambers and lead to stack emissions. The major conclusions from this study are that (1) transient puffs are formed due to the semi-batch feed nature of the combustion process (causing a local oxygen deficiency) and high water content of the desensitized propellant; (2) in batch-fed combustors, puffs can contribute to most of the organic emissions (which are relatively low) measured with US EPA sampling and analytical methods; (3) it is estimated that batch-fed combustion contributes up to 7-18 times more emissions than steady-state combustion will generate; (4) by applying dispersion analyses to determine the amount of oxygen deficiency in the flame zone, the combustion zone concentration of CO during batch-fed operation could be as high as 160,000 ppm, compared to a measured peak stack concentration of 1200 ppm CO; and (5) an organic sample is collected and averaged over at least a 2-h period that smooths out the transient peaks of organics emissions during batch-fed operation. For emissions that are associated with long-term potential health impacts, this is an appropriate sampling method. However, if a compound has a short-term potential health impact, it may be important to measure the time-resolved emissions of the compound.
Hart, John R.
p. 559 - 569
(2007/10/03)

Vulcanizing agents for unsaturated rubber mixtures
The invention relates to new polymeric sulfur compounds, their preparation and their use as vulcanizing agents for unsaturated rubber mixtures.
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(2008/06/13)

M(SCN)2 (M = Eu, Sr, Ba): Crystal structure, thermal behaviour, vibrational spectroscopy
Single crystals of M(SCN)2 (M = Eu, Sr, Ba) have been obtained via metathesis of NaSCN and MCl2 (M = Eu, Sr, Ba) at 340°C. The isotypic crystal structures of the thiocyanates M(SCN)2 (C2/c, Z = 4, Eu: a = 979.3(2), b = 660.8(1), c = 815.7(2) pm, β = 91.58(3)°, Rall = 0.0245, Sr: a = 985.5(2), b = 662.9(2), c = 819.6(2) pm, β = 91.29(3)°, Rall = 0.0435, Ba: a = 1018.8(2), b = 687.2(1), c = 852.2(1) pm, β = 92.43(2)°, Rall = 0.0392) contain alternating layers of M2+ and SCN-. According to M(SCN)4/4(NCS)4/4 M2+ is eight-coordinated by four sulfur and four nitrogen atoms forming a square antiprism. Thermal investigations show that the compounds melt without decomposition. Vibrational spectroscopic investigations are presented and discussed. WILEY-VCH Verlag GmbH, 2001.
Wickleder, Claudia
p. 1693 - 1698
(2008/10/08)

Thioformaldehyde S-sulfide (Thiosulfine)
Matrix isolation spectroscopy allows the direct identification of ylide 1 and its cyclic isomer 2. They were obtained by pyrolysis of 1,2,4-trithiolane under high vacuum; the cyclic compound forms from 1 by thermal ring closure in a kinetically controlled reaction.
Mlosto, Grzegorz,Romaski, Jaroslaw,Reisenauer, Hans Peter,Maier, Gnther
p. 393 - 396
(2007/10/03)

Ultraviolet absorption spectrum of cyclic CS2 in solid Ar
Linear CS2 dispersed in solid Ar was irradiated with an excimer laser at 193 nm to form cyc-CS2 of which infrared (IR) identification and theoretical calculations were reported previously. We recorded an ultraviolet (UV) absorption spectrum with two progressions (330-380 nm) that correlate well with variations in intensities of IR absorption of cyc-CS2 upon photolysis of linear CS2 at various stages; hence we assign it to electronic transitions of cyc-CS2. Based on theoretical calculations and vibronic symmetry, we tentatively assign progression A to transition 21B2←X1A1 and progression B to 21B1←X1A1 of cyc-CS2.
Lo, Wen-Jui,Lee, Yuan-Pern
p. 71 - 75
(2008/10/08)

Evolution of products in the combustion of scrap tires in a horizontal, laboratory scale reactor
A horizontal laboratory reactor was used to study the evolution of byproducts from the combustion of scrap tires at five nominal temperatures (ranging from 650 to 1050 °C) and different oxygen:sample ratios A model was used to calculate the bulk air ratio (λ), and the oxygen consumption was discussed considering this ratio λ. More than 100 volatile and semivolatile compounds were identified and quantified by gas chromatography mass spectrometry, plotting their yields vs the bulk air ratio and temperature. Five different behaviors considering the bulk air ratio and the temperature were identified.
Fullana,Font,Conesa,Blasco
p. 2092 - 2099
(2007/10/03)

Initiation of thermal reactions of sulfur compounds by dialkyl selenides
The use of diethyl selenide (20-40 mol %) as initiator in the gas-phase synthesis of thiophene from diethyl disulfide and acetylene increases the selectivity of the process and the yield of thiophene from 40 to 92%. As a result, this reaction becomes the most efficient preparative method for the synthesis of thiophene and also of selenophene which is formed in up to 70% yield. The complete conversion of both sulfur-and selenium-containing reagents is attained. Due to much different boiling points, thiophene and selenophene can readily be separated by rectification of the reaction mixture. Dialkyl selenides also initiate other thermal reactions of hydrogen sulfide and organic sulfides.
Deryagina,Sukhomazova,Levanova,Shilkina,Korchevin
p. 359 - 363
(2007/10/03)

Mechanisms of acid decomposition of dithiocarbamates. 2. Efficiency of the intramolecular general acid catalysis
The acid decomposition of ethylenebis(dithiocarbamate) (EbisDTC) and glycinedithiocarboxylate (glyDTC) was studied in water at 25 °C in the range of rio -5 to pH 5. The acid dissociation constants of all species involved were calculated from LFER and from the pH-rate profiles. According to the pK(a) of the parent amine of the reactive species, both compounds decompose through the dithiocarbamate anion and a zwitterion intermediate. The intermolecular N-protonation rate constant of the carboxylic conjugate acid of glyDTC anion is 12.6 M-1 s-1, slower than the C-N breakdown. This species also cleaves through an intramolecular general acid-catalyzed mechanism where the rate constant for the N-protonation is (7.1 ± 4.2) x 103 s-1 and the efficiency of the proton-transfer step as measured by the effective molarity is (5.6 ± 3.3) x 102 M. The acid decomposition of the dithiocarbamic conjugate acid of EbisDTC anion proceeds through a fast N- protonation and a slower C-N breakdown. The intramolecular general acid catalysis rate constant is (8.2 ± 2.8) x 106 s-1, but the efficiency of this fast proton transfer is only (14.3 ± 4.9) M. The intramolecular general acid catalysis of the free acid forms of the carboxylic and dithiocarbamic groups is unfavorable for about 4 kcal mol-1 with respect to the protonation of the external hydron, and consequently, no external buffer catalysis is expected to be observed for dithiocarbamates that decompose through a zwitterion intermediate. The difference between the pK(b) of the proton acceptor and the pK(a) of the donor follows the order of the proton efficiency. Estimation of the strength of the hydrogen bonding in the reagent and product supports the assumption that a thermodynamically favorable change of hydrogen bonding from reagent to product increases the efficiency of proton transfer.
Humeres, Eduardo,Debacher, Nito A.,Sierra, M. Marta De S.
p. 1807 - 1813
(2007/10/03)

The N-(1-phenylethyi)dithiocarbamate anion. Electronic transitions, ultraviolet and CD spectra, and reversible formation of its ammonium salts
The UV and CD spectra of tetrabutylammonium (S)-N-(1-phenylethyl)dithiocarbamate (3c) have been recorded in acetonitrile and in absolute ethanol. In the dithiocarbamate anion, the sulfur lone pairs are expected to interact to give a low-energy symmetric combination (n+) and an antisymmetric combination (n-) with the higher energy. The UV spectrum was interpreted with the aid of CNDO/S calculations, and the CD spectrum with calculations by the Schellman matrix method. The CD spectrum contains a medium-strong positive band at 230 nm, which lacks a counterpart in the UV spectrum and was initially tentatively assigned to the n+→π1* transition. However, the theoretical calculations predict a negative sign for this band, and consequently no assignment for the 230 nm band can be given at present. Except for the 230 nm band, the calculations predict correct signs and qualitatively correct intensities for the CD bands between 200 and 400 nm in a narrow range of orientations of the 1-phenylethyl group with respect to the dithiocarbamate ion, and it is expected that the favoured conformation falls in this conformational range. Similar studies of (S)-(1-phenylethyl)ammonium (S)-N-(1-phenylethyl)dithiocarbamate (3a) and triethyl-ammonium (S)-N-(1-phenylethyl)dithiocarbamate (3b) failed because these salts decompose in solution with ultimate formation of carbon disulfide. This decomposition has been studied by UV spectroscopy, and a mechanism has been proposed.
Rang, Knut,Sandstroem, Jan
p. 827 - 832
(2007/10/03)

Mechanisms of acid decomposition of dithiocarbamates. 1. Alkyl dithiocarbamates
The acid decomposition of some substituted methyldithiocarbamates was studied in water at 25°C in the range of rio -5 and pH 5. The pH-rate profiles showed a bell-shaped curve from which were calculated the acid dissociation constants of the free and conjugate acid species and the specific acid catalysis rate constants k(H). The Bronsted plot of k(H) vs pK(N), the dissociation constant of the conjugate acid of the parent amine, suggests that the acid cleavage occurs through two mechanisms that depend on the pK(N). The plot presents a convex upward curve with a maximum at pK(N) 9.2, which is consistent with the cleavage of the dithiocarbamate anion through a zwitterion intermediate and two transition states. For pK(N) 9.2, the C-N bond breakdown is the slowest step, and according to the inverse SIE, the transition state changes rapidly with the increase of pK(N) to a late transition state. The plot shows a minimum at pK(N) ?10, indicating that a new mechanism emerges at higher values, and it is postulated that it represents a path of intramolecular S to N proton-transfer concerted with the C-N bond breakdown. The thiocarbonyl group acts as a powerful electron- withdrawing group, decreasing the basicity of the nitrogen of the parent amine by 14.1 pK units.
Humeres, Eduardo,Debacher, Nito A.,Marta de S. Sierra,Franco, Jose Dimas,Schutz, Aldo
p. 1598 - 1603
(2007/10/03)

Thermal decomposition of copper(I) thiocarbamide chloride hemihydrate
Two combinations of simultaneous thermoanalytical techniques (TG+DTA and TG+EGA) were used to study the thermal decomposition of the title compound in order to gain a better insight into the spray pyrolytic processes leading 10 Cu2-xS and CuInS2 thin films. After dehydration a complex sequence of reactions starts above 220°C leading through several intermediates to the formation of CuO in air at 1000°C. In an inert atmosphere Cu2S is formed which in helium above 800°C partly decomposes to Cu. XRD and FTIR were used to identify the intermediate solid phases which in air included CuCl, Cu2OSO4, Cu2OCl2 and CuSO4. EGA-FTIR confirmed the complex reaction mechanism with NHs, HCl, H2O, COS, CO2 and some HCN as main gaseous products under oxidative conditions.
Krunks,Leskelae,Mannonen,Niinistoe
p. 355 - 364
(2008/10/08)

Synthesis, spectroscopic characterization, and structural studies of organogermanium tri- and monothiocarbonates. Crystal structures of Me2Ge[S2CSEt]2, Ph3Ge[SCO2Me], Ph3Ge[SCO2(i-Pr)], and Ph2Ge[SCO2Me]2
Two series of S-alkyl trithiocarbonate derivatives of dimethylgermane, Me2Ge[S2CSR]2, and halodiphenylgermane, Ph2GeX[S2CSR], where R = Me, i-Pr, n-Pr, n-Bu and X = Cl, Br, and three series of O-alkyl monothiocarbonate derivatives of triphenylgermane, Ph3Ge[SCO2R], diphenylgermane, Ph2Ge[SCO2R], and trimethylgermane, Me3Ge[SCO2R], where R = Me, i-Pr, and n-Pr, have been prepared in 73-92% yields by the reaction of the potassium or sodium salt of the appropriate tri- or monothiocarbonic acid with dichlorodimethyl-, chlorotriphenyl-, dichlorodiphenyl-, and chlorotrimethylgermane. The compounds were principally characterized by infrared, Raman, and 1H and 13C NMR spectroscopy, including some variable temperature studies, as well as by mass spectrometry. Me2Ge[S2CSEt]2, 1: P21/m (No. 11) with cell parameters a = 6.647(4) A, b = 7.423(2) A, c = 16.290(4) A, β = 91.07(3)°, V = 803.6(4) A3, Z = 2, R = 0.0484, Rw = 0.0485. Ph3Ge[SCO2Me], 13: P1 (No. 2) with cell parameters a = 9.970(4) A, b = 10.660(3) A, c = 9.853(2) A, α = 101.78(2)°, β = 109.98(2)°, γ = 89.76(3)°, V = 961.0(5) A3, Z = 2, R = 0.0534, Rw = 0.0451. Ph3Ge[SCO2(i-Pr)], 14: P1 (No. 2) with cell parameters a = 14.386(7) A, b = 18.598(6) A, c = 9.223(3) A, α = 102.85(3)°, β = 94.58(3)°, γ = 108.13(3)°, V = 2256(1) A3, Z = 2, R = 0.0545, Rw = 0.0552. Ph2Ge[SCO2Me]2, 16: Cc, (No. 9) with cell parameters a = 11.790(4) A, b = 13.696(5) A, c = 23.232(6) A, β = 92.26(3)°, V = 3748(2) A3, Z = 8, R = 0.0563, Rw = 0.0512. The immediate environment about Ge is that of tetrahedral but the orientations of the thiocarbonate groups display interesting features.
Drake, John E.,Yang, Jincai
p. 319 - 334
(2007/10/03)

Preparation and Characterization of Trimethylgermanium-Sulfur Compounds Derived from 2-Dithiocarbamoyl-3-dithiocarbonylthiopropionate. Crystal Structures of [NH4]3[S2CSCH2CH(NHCS 2)CO2] and Me3GeO2C(-CHNHC(S)SCH2-)
Attempts to isolate organogermanium derivatives at three different sites in a ligand prepared from cysteine are reported. The formation of Me3GeS2CSCH2CH(NHCS2GeMe 3)CO2GeMe3 is established by NMR spectroscopy. This derivative undergoes CS2 elimination followed by further decomposition and rearrangement to yield Me3GeO2C(-CHNHC(S)SCH2-). The crystal structures of Me3GeO2C(-CHNHC(S)SCH2-) and the starting salt, [NH4]3[S2CSCH2CH(NHCS 2)CO2] were determined. [NH4]3[S2CSCH2CH(NHCS 2)CO2] (1) crystallizes in the hexagonal space group (P65, No. 170) with the cell parameters a = 10.305(4) A, b = 10.305(4) A, c = 23.740(5) A, V = 2183(1) A3, Z = 6, R = 0.0553, Rw = 0.0438. Me3GeO2C(-CHNHC(S)SCH2-) (4) crystallizes in the orthorhombic space group (P212121, No. 19) with the cell parameters a = 10.463(6) A, b = 22.644(5) A, c = 10.241(5) A, V = 2426(1) A3, Z = 4, R = 0.0571, Rw = 0.0472. The immediate environment about Ge is that of tetrahedral with the orientation of the terminal C=O bond being toward germanium. The Ge- - -O distance of 3.02(1) A is clearly less that the sum of the van der Waals radii of germanium and oxygen raising the possibility of a weak interaction. A plausible mechanism for the conversion of Me3GeCSCH2CH(NHCS2GeMe3)CO 2GeMe3 into Me3GeO2C(-CHNHC(S)SCH2-) is proposed.
Drake, John E.,Yang, Jincai
p. 2968 - 2974
(2008/10/08)

Formation of thiophenethiols by flash vacuum pyrolysis of 1,6,6aλ4-trithiapentalenes
The thermal behaviour of 1,6,6aλ4-trithiapentalene 3 and some methyl-substituted derivatives 5-7 has been investigated using a combination of flash vacuum pyrolysis (FVP), tandem mass spectrometry (MS-MS) and matrix isolation IR spectroscopy. the main products of the fragmentation (losses of CS and/or CH2=C=S) are shown to be thiophene-3-thiones (or the thiol tautomers) which are also shown to be readily available by direct sulfuration of thiophenes in chemical ionization (CS2 reagent gas) conditions.
Flammang, Robert,Barbieux-Flammang, Monique,Gerbaux, Pascal,Pedersen, Carl Th.
p. 1261 - 1264
(2007/10/03)

Combined experimental and theoretical study of the protonation of polyfluorobenzenes [C6H(6-n)F(n)] (n = 0-6)
In a recent high-pressure mass spectrometric revision to the gas-phase basicity scale (J. E. Szulejko and T. B. McMahon, J. Am. Chem. Sec. 115, 7839 (1993)), it was observed that the proton affinity for hexafluorobenzene was 24 kcal mol-1 (1 kcal = 4.184 kJ) lower than the accepted National Institute of Science and Technology (NIST) database value of 177.7 kcal mol-1 (S. G. Lias et al., J. Phys. Chem. Ref. Data 17, Suppl. 1 (1988)). Furthermore, the proton affinities for most other polyfluorobenzenes were also found to differ substantially from the NIST values. For many of the polyfluorobenzenes large protonation entropy changes were noted, which were substantially greater than then those expected from rotational symmetry number changes alone. In view of these observations, MP2/6-31G**/HF/6-31G** ab initio calculations were undertaken to investigate further the proton affinity and entropy changes with respect to the degree of fluorine substitution. The present proton affinity variations found for the polyfluorobenzenes (hexaflorobenzene excepted) can be interpreted with the aid of the ab initio results in terms of a simple additivity scheme. Each fluorine substituent para, meta, ortho or ipso to the ring protonation site will induce an incremental proton affinity change with respect to benzene of 1.5, -7.0, -1.5 and -19.0 kcal mol-1, respectively. This additivity scheme can also be used to rationalize the re-evaluated proton affinities for the polymethylbenzenes and m- and o-fluorotoluenes. The corresponding methyl increments are 7.5, 5.5, 2.5 and 1.0 kcal mol-l for para, meta, ortho and ipso protonation respectively. From the present ab initio statistical thermodynamic analysis of the various protonation entropy components, it was concluded that the low frequency vibrations are almost exclusively responsible for the large excess entropy changes observed experimentally. Ab initio calculated barriers for 1,2 proton shifts in arenium species available in the literature are concluded to be too large to allow the existence of a so-called dynamic proton. Large excess protonation entropies are noted from the literature for polymethylbenzenes, naphthalene and 1-methylnaphthalene.
Szulejko,Hrusak,McMahon
p. 494 - 506
(2007/10/03)

Cycloaddition of Bu(n)3P·CS2: Direct one-pot conversion of strained double bonds to 2-alkylidene-1,3-dithiolanes
Reaction of the adduct between tri-n-butylphosphine and carbon disulfide 1 with norbornene gives the novel zwitterionic structure 9. In solution this dissociates to the ylide 8 which undergoes Wittig reaction with aldehydes. Using the same method, the overall conversion of the strained double bond in a variety of bicyclo[2.2.1]alkenes into 2-benzylidene-1,3-dithioles 15-24 has been achieved and the reaction is also applicable to norbonnadiene, affording bis-dithiolanes 29-31.
Aitken, R. Alan,Carcas, Katriona,Hill, Lawrence,Massil, Tracy,Raut, Swati V.
p. 2261 - 2270
(2007/10/03)

The formation of 1,2-propadiene-1,3-dithione (carbon subsulfide) from flash vacuum pyrolysis of 1,2-dithiole-3-thiones
1,2-Propadiene-1,3-dithione (carbon subsulfide) has been obtained by flash vacuum pyrolysis of alkylthio substituted 1,2-dithiole-3-thiones in the temperature range 800-1000°C. The dithione was isolated and characterized in an argon matrix at 10 K.
Pedersen, Carl Th.
p. 4805 - 4808
(2007/10/03)