Showing papers by "University of Duisburg-Essen published in 1983"
TL;DR: In this paper, the same clockwise and staggered conformation as in the starting isomer of 1, namlich 1a was investigated by an X-ray analysis, and the results confirmed that the original isomer is a pure clockwise isomer.
Abstract: Bis[2-methyl-1-(trimethylsilyl)-η-1,2-azaborolinyl]eisen (1) wird durch Lithium-2,2,6,6-tetramethylpiperidid [Li(TMP)] am Stickstoffatom unter Abspaltung der Si(CH3)3-Gruppen lithiiert. Mit tert-Butylalkohol entsteht daraus Bis(2-methyl-η-1,2-azaborolinyl)eisen (2). Eine Rontgenstrukturanalyse von 2 bestatigt dieselbe gleichlaufige und gestaffelte Konformation wie beim Ausgangsisomeren von 1, namlich 1a. Verwendet man zur Lithiierung ein Isomerengemisch mit gleich- und gegenlaufigen Azaborolinylringen (1a und b) und methyliert mit CH3I, so bildet sich Bis(1,2-dimethyl-η-1,2-azaborolinyl)eisen (4) als Isomerengemisch (4a und b). 4 kann auch direkt uber den methylierten Ring 6 und FeBr2 hergestellt werden. Die Lithiierung von 1a und anschliesende Ethylierung mit C2H5Br fuhrt zu Bis(1-ethyl-2-methyl-η-1,2-azaborolinyl)eisen (5), wiederum als reines, gleichlaufiges Isomeres.
Azaborolinyl Complexes, VIII. Chemical and Spectroscopic Investigations on Bis(η-1,2-azaborolinyl)iron Complexes
Bis[2-methyl-1-(trimethylsilyl)-η-1,2-azaborolinyl]iron (1) is lithiated at the nitrogen atom by lithium 2,2,6,6-tetramethylpiperidide [Li(TMP)] with elimination of the Si(CH3)3 groups. With tert-butyl alcohol bis(2-methyl-η-1,2-azaborolinyl)iron (2) is formed which has been investigated by an X-ray analysis. It confirms the same clockwise and staggered conformation as in the starting isomer of 1, namely 1a. If a mixture of isomers with clockwise and anti clockwise azaborolinyl rings (1a and b) is applied for lithiation and a methylation is carried out with CH3I, bis(1,2-dimethyl-η-1,2-azaborolinyl)iron (4) is formed as a mixture of isomers (4a and b). 4 may also be synthesized via the methylated ring 6 and FeBr2. Lithiation of 1a and following ethylation with C2H5Br leads to bis(1-ethyl-2-methyl-η-1,2-azaborolinyl)iron (5), again as a pure clockwise isomer.
22 citations
TL;DR: It was observed that long-term prophylaxis with TMP/SMZ modified the normal aspect of the fecal biotop culture, not only by suppressing the aerobic gram-negative bacteria, but also by allowing certain clostridia to appear.
Abstract: During 59 periods of hospitalisation, 39 patients with either acute myeloid leukemia (22), acute lymphatic leukemia (9), acute undifferentiated leukemia (1), blastic crisis of chronic myeloid leukemia (6) or high-grade malignant non-Hodgkin lymphoma (1) were subjected to aggressive polychemotherapy after selective decontamination of the gut. The patients were given an amphotericin B suspension in a dosage of 1.2 g/day for two days, after which one tablet of trimethoprim/sulphamethoxazole (TMP/SMZ) (160 mg TMP and 800 mg SMZ) t.i.d. was added to prevent endogenous infections by gram-negative aerobic bacteria or moulds and to maintain the “colonisation resistance” endowed by the anaerobes. During 16 of the 59 periods of hospitalisation, no potentially pathogenic aerobic bacteria were isolated, TMP/SMZ-resistantEscherichia coli were the etiological agent of septicemia in two patients, and resistantKlebsiella pneumoniae andPseudomonas aeruginosa in two other patients. These bacteria were cultured from the patients fecal samples prior to the development of septicemia. We observed that long-term prophylaxis with TMP/SMZ modified the normal aspect of the fecal biotop culture, not only by suppressing the aerobic gram-negative bacteria, but also by allowing certain clostridia to appear. We differentiated 207 clostridia from the fecal samples of 29 patients and observed a predominance of TMP/SMZ-resistantClostridium difficile, Clostridium innocuum andClostridium clostridiiforme. C. difficile was also isolated from the blood culture of a neutropenic patient treated with TMP/SMZ and proved to be very toxic in the Verocell culture.
12 citations
TL;DR: In this article, the reaction of tetraethylammonium tricarbonyl (η5-3,5-diphenyl-1-thiacyclohexadienyl 1-oxide) with methyl fluorosulfonate and N-sulfinyldimethylimmonium tetrafluoroborate, respectively, yield the 2H-thiopyran complexes 4 and 9 instead of the expected λ4-thIabenzene complexes 3 and 8.
Abstract: Bei der Reaktion von Tetraethylammonium-tricarbonyl(η5-3,5-diphenyl-1- thiacyclohexadienyl-1-oxid)chromat (2a) mit Fluorsulfonsaure-methylester bzw. N-Sulfinyldimethylimmonium-tetra-fluoroborat werden statt der erwarteten λ4-Thiabenzolkomplexe 3 und 8 die dazu isomeren 2H-Thiopyrankomplexe 4 und 9 isoliert. Die Molekulstruktur von 9 wurde durch Rontgenstrukturanalyse aufgeklart.
Transition Metal Sulfur Ylide Complexes, XV. Synthesis of 2H-Thiopyran Chromium Complexes from Tetraethylammonium Tricarbonyl- (η-3,5-diphenyl-1-thiacyclohexadienyl 1-oxide)chromate and Hard Electrophiles
The reactions of tetraethylammonium tricarbonyl(η5-3,5-diphenyl-1-thiacyclohexadienyl 1-oxide)chromate (2a) with methyl fluorosulfonate and N-sulfinyldimethylimmonium tetrafluoroborate, respectively, yield the 2H-thiopyran complexes 4 and 9 instead of the expected λ4-thiabenzene complexes 3 and 8. The molecular structure of 9 was elucidated by X-ray analysis.
12 citations
TL;DR: In this article, the deoxygenation of anti-Tricarbonyl(1-methyl-3,5-diorganyl-λ6thiabenzene oxide)chromium,molybdenum, and -tungsten as a Novel Synthetic Route to λ4-Thiabienzene complexes is described.
Abstract: Bei der Reaktion der anti-Konfigurierten λ6-Thiabenzoloxid-Komplexe 5a–e, 6e und 7e mit Natrium-bis(2-methoxyethoxy)aluminiumhydrid werden die λ4-Thiabenzol-Komplexe 2a–e, 3e und 4e erhalten. Nach den Spektren sind die bisher unbekannten ylidischen Heterocyclen in den neuartigen Komplexen deutlich starkere Donorliganden als die entsprechenden λ6-Thiabenzoloxide.
Transition Metal Sulfur Ylide Complexes, XVIII. The Deoxygenation of anti-Tricarbonyl(1-methyl-3,5-diorganyl-λ6thiabenzene oxide)chromium,-molybdenum, and -tungsten as a Novel Synthetic Route to λ4-Thiabenzene Complexes
From the reaction of anti-configurated λ6-thiabenzene oxide complexes 5a–e, 6e, and 7e with sodium bis(2-methoxyethoxy)aluminium hydride λ4-thiabenzene complexes 2a–e, 3e, and 4a are obtained. The hitherto unknown ylidic heterocycles in the novel complexes behave as significantly stronger donor ligands as the related λ6-thiabenzene oxides as is inferred from spectroscopic data.
10 citations
TL;DR: In this article, the reaction of (CH3CN)3M(CO)3(M Cr, Mo, W) with thiabenzene oxides 1b-d complexes such as (thibenzene oxide)M( CO)3 are isolated.
Abstract: Bei der Reaktion von (CH3CN)3M(CO)3(M Cr, Mo, W) mit den Thiabenzoloxiden 1b–d werden Komplexe des Typs (Thiabenzoloxid)M(CO)3 gebildet. Isomere werden jedoch nur fur das Chrom erhalten. Mit dem Di-tert-butylderivat 1e als Liganden werden dagegen andere Verhaltnisse angetroffen. Hier entsteht allein der anti-isomere Chromkomplex 5e, dafur werden aber fur Molybdan und Wolfram syn- und anti-konfigurierte Komplexe gebildet.
Transition Metal Sulfur Ylide Complexes, XVI. 1-Methyl-3,5-diorganylthiabenzene 1-Oxide Complexes: Synthesis and Stereochemistry
From the reaction of (CH3CN)3M(CO)3(M Cr, Mo, W) with thiabenzene oxides 1b–d complexes such as (thiabenzene oxide)M(CO)3 are isolated. Isomers are only obtained for chromium. Employing di-tert-butyl derivative 1e as a ligand a different situation is encountered. Here, only the anti-isomeric chromium complex 5e is formed. On the other hand with molybdenum and tungsten syn- and anti-configurated complexes are obtained.
8 citations
TL;DR: In this article, the complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 620. DOI:10.1002/anie.198306200
Abstract: The complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 620. DOI:10.1002/anie.198306200
7 citations
TL;DR: In this article, the 1-Alkyl-3,5-diphenyl-λ4-thiabenzene chromium complexes were oxidized by NOPF6 in CH2Cl2 at −70°C, yielding the cationic dicarbonylnitrosyl complexes 3a-f. The X-ray structure analysis of 3b showed that the molecule in the solid state possesses no local Cs-symmetry.
Abstract: Die 1-Alkyl-3,5-diphenyl-λ4-thiabenzol-Chromkomplexe 2a–f werden durch NOPF6 in CH2Cl2 bei −70°C unter Bildung der kationischen Dicarbonylnitrosyl-Spezies 3a–f oxidiert. Die temperaturabhangigen 1H-NMR-Spektren dieser Komplexe deuten auf gehinderte Rotation der Ringe um das (CO)2(NO)Cr+-Fragment hin. Die Rontgenstrukturanalyse von 3b zeigt, das das Molekul im Kristall keine lokale Cs-Symmetrie mehr besitzt.
Transition Metal Sulfur Ylide Complexes, XIV. π-Complexes of 1-Alkyl-3,5-diphenyl-λ4-thiabenzenes with Dicarbonylnitrosylchromium
1-Alkyl-3,5-diphenyl-λ4-thiabenzene chromium complexes 2a–f are oxidized by NOPF6 in CH2Cl2 at −70°C, yielding the cationic dicarbonylnitrosyl complexes 3a–f. The temperature dependence of the 1H NMR spectra of 3a–f is consistent with a hindered rotation of the ring ligands. The X-ray structure analysis of 3b shows that the molecule in the solid state possesses no local Cs-symmetry.
3 citations