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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 1684-1695 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Darstellung und Charakterisierung von Bis(thioacyl)tri- und -tetrasulfidenDurch Umsetzung von Dithiocarbonsäuren mit Schwefeldichlorid oder Dischwefeldichlorid werden einige Bis(thioacyl)tri- 1 und -tetrasulfide 2 dargestellt. Die aromatischen Bis(thioacyl)-sulfide (1, 2, R = Arylrest) sind thermisch stabile und nicht feuchtigkeitsempfindliche Kristalle. Die n →π*-Übergänge der Thiocarbonylgruppen in Bis(thioacyl)sulfiden [RC(S) - Sx - (S)CR, x = 1 - 4] sind von der Anzahl x der Schwefelatome abhängig. Ferner stimmt der merkliche Unterschied zwischen den n →π*-Übergängen (λmax) der Monosulfide vom Typ RC(S)S(S)CR und denen der Sulfide RC(S) - Sx - (S)CR (x = 2 - 4) mit dem Ergebnis von ab-initio-Molekül-Orbital-Berechnungen an Bis(thioformyl)sulfiden [HC(S) — Sx — (S)CH, x = 1 - 3] überein. Die Rechnungen zur Bestimmung der Ladungsverteilung und Grenzorbital-Elektronendichte sagen einen ladungskontrollierten Angriff von Nucleophilen oder Elektronen-Donoren auf den Sulfid-Schwefel voraus, während die Reaktion mit dem Thiocarbonyl-Schwefel der Grenzorbital-Kontrolle unterliegt.
    Notes: Bis(thioacyl) tri- 1 and tetrasulfides 2 have been prepared by the reaction of dithiocarboxylic acids with sulfur- or disulfur dichloride. The crystalline aromatic bis(thioacyl) sulfides (1, 2, R = aromatic) are stable towards heat and moisture. The n →π* transitions (λmax) of the thiocarbonyl groups of bis(thioacyl) sulfides [RC(S) — Sx — (S)CR, x = 1 - 4] are influenced by the number x of sulfur atoms. In addition, the remarkable difference in the n →π* transitions (λmax) between monosulfides [RC(S)S(S)CR] and polysulfides [RC(S) - Sx - (S)CR, x = 2 - 4] shows no contradiction with the results of the ab initio molecular-orbital calculation by employing bis(thioformyl) sulfides [HC(S) - Sx - (S)CH, x = 1 - 3] as model compounds. The results of the calculation of the charge distribution and the frontier-electron densities show that nucleophiles or electron-donating reagents attack the sulfide sulfur in a charge-controlled reaction and the thiocarbonyl sulfur in a frontier-orbital-controlled reaction.
    Additional Material: 6 Tab.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 1696-1708 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Darstellung und einige Reaktionen von Selen- und Tellur-bis(dithiocarboxylaten)Durch Umsetzung von Piperidinium- oder Natrium-dithiocarboxylaten 1 mit Natrium-seleno-oder -telluropentathionaten wurden die Selen- 2 und Tellur-bis(dithiocarboxylate) 3 dargestellt. Die orangefarbenen oder roten Kristalle sind thermisch stabil und nicht feuchtigkeitsempfindlich. Durch Umsetzung von 2 oder 3 mit Halogenen oder N-Chlor- oder N-Bromsuccinimid wurden Haloselen- 4, 5 und Halotellur-dithiocarboxylate 6-8 mit guten Ausbeuten erhalten. Die n →πast;-Übergänge der Thiocarbonylgruppen in 2-8 treten bei kleineren Wellenlängen auf (hypsochrome Verschiebung) als die der entsprechenden Bis(thioacyl)-trisulfide sowie Dithio- und Thionselenolester.
    Notes: A number of selenium- 2 and tellurium bis(dithiocarboxylates) 3 have been prepared by the reaction of piperidinium or sodium dithiocarboxylates 1 with sodium seleno- and telluropentathionates. The orange or red products are stable towards heat and moisture. It was found that 2 and 3 react with halogens and N-chloro- and N-bromosuccinimide to give the corresponding haloselenium- 4, 5 and halotellurium dithiocarboxylates 6-8 in good yields. The n →π* transitions of the thiocarbonyl groups in 2-8 are observed in a region of shorter wavelengths (hypsochromic shift) than those of the corresponding bis(thioacyl) trisulfides and dithio- and thioneselenol esters.
    Additional Material: 4 Tab.
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  • 3
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sodium 2 and potassium selenocarbamates 3 were found to be synthesized in moderate to good yields by the reaction of carbamoyl chlorides with sodium and potassium selenides. The salts 2 and 3 reacted with alkyl halides and organo-germanium, -tin, and -lead chlorides to give the corresponding esters 7-9 in good yields.
    Additional Material: 2 Tab.
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  • 4
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aromatic diselenoic acid Se-methyl esters 1 react with amines at 0°C in tetrahydrofuran (THF) to yield selenoamides in moderate to good yields. The reaction course is highly dependent on the steric requirements of both starting materials. In the reactions of the ester 1a with 2-methylpiperidine and of the ester 1b with piperidine, the starting materials disappear within 1 hour with the liberation of black selenium, but the corresponding selenoamides are not produced. These results may be ascribed to the steric congestion caused by the formation of the selenoamide group from the tetrahedral intermediate 15. X-ray crystal structure analyses of the selenoamides 3 and 9 have been performed. The bond length of C(Se)—N is shorter than a carbon nitrogen single bond. On the other hand, the C=Se bond is longer than that of the ordinary carbon-selenium double bond. These results are indicative of the efficient delocalization of the electrons of nitrogen to the carbon-selenium double bond. The double bond character between the carbon attached to selenium and the nitrogen is also supported by the nitrogen atom showing sp2 character. When a methyl group is introduced at the meta position of the aromatic ring, the deviation of the aromatic ring from the plane involving the carbon-selenium double bond and nitrogen atom becomes substantially large, perhaps due to the steric bulkiness of the selenium atom.
    Additional Material: 2 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 5 (1994), S. 31-35 
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of SeCl4 with lithium bis(trimethylsilyl)amide and terminal acetylenes in the presence of BuLi or AIBN afforded the corresponding dialkynyl selenides in moderate to high yields. The reaction may proceed via a selenium amide 7 and an alkynyl selenium amide 8. The comparison of 13C NMR spectra of dialkynyl selenides and tellurides has disclosed that the differences of the chemical shift of acetylenic carbons between Se and Te derivatives are consistent regardless of their substitution patterns. Ab initio molecular orbital calculations are reported for dialkynyl ether and chalcogenides. The calculated structures, charge distributions, and orbital energies are discussed.
    Additional Material: 2 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 417-422 
    ISSN: 0009-2940
    Keywords: Selenocarboxylates, O-triorganosilyl ; Selenone esters ; Seleno-selenol rearrangement ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of O-triorganosilyl selenocarboxylates 2 are prepared by the reaction of sodium or potassium selenocarboxylate 1 with triorganosilyl chlorides. The selenone esters 2 are stable towards heat, but labile towards moisture, and are formed via Se-triorganosilyl selenocarboxylate 3. In the mass spectrometer, isomerization of 2 to its less stable selenol ester 3 takes place, resembling the Schönberg thione-thiol rearrangement.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 898-910 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of sodium selenocarboxylates 2 were isolated from the reaction of diacyl selenides with sodium ethanolate and characterized. A convenient preparation of the sodium salts 2 by the direct reaction of acyl chlorides with sodium selenide was also established. The salts are colourless to slightly pale yellow crystals and labile towards moisture. They readily react with alkyl iodides at room temperature to give the corresponding Se-alkyl esters 3.
    Additional Material: 1 Ill.
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