Showing papers by "Bernt Krebs published in 1985"
TL;DR: In this article, the synthesis and studies on the reactive behavior of metallophospha-alkenes are reported, where the reactive behaviour of metallo-phasophasophase is investigated.
Abstract: The synthesis and studies on the reactive behaviour of metallophospha-alkenes are reported.
25 citations
24 citations
Journal Article•
TL;DR: In this article, the authors utilise the spectrometrie RMN de 11 B for etudier la nature structurale des differentes phases obtenues dans les systemes bore-soufre, bore-selenium and bore-tellure.
Abstract: Utilisation de la spectrometrie RMN de 11 B pour etudier la nature structurale des differentes phases obtenues dans les systemes bore-soufre, bore-selenium, bore-soufre-selenium et bore-tellure
19 citations
TL;DR: In this article, the reaction of an amino acid with diazoalkanes leads to Δ1-diazaphospholines 3, 7, 11, and 12.
Abstract: Amino[(trimethylsilyl)methylen]thioxophosphoran 1 reagiert mit Diazoalkanen zu den Δ1-Diazaphospholenen 3, 7, 11 und 12. Diese stabilisieren sich unter 1,3-Trimethylsilyl-Verschiebung zu den Δ2-Diazaphospholenen 4 und 8 bzw. zerfallen unter [1 + 4]-Cycloreversion zu Azin (14 und 15) und dem Aminothioxophosphan 13. 13 konnte durch Reaktion mit Diazoalkan als Aminomethylenthioxophosphoran (18 und 19) abgefangen werden. Durch Entschwefelung von 18 bzw. 19 mittels Triphenylphosphan ist das entsprechende Phosphan-System 20 bzw. 21 zuganglich. tert-Butylazid (22) reagiert mit 1 zum Triazaphospholen 23, das thermisch unter Trimethylsilyl-Wanderung zu 24 isomerisiert und photochemisch unter N2-Eliminierung das λ5-Phosphiridin 25 liefert, ein Verbindungssystem, das ebenfalls durch Umsetzung eines Aminoiminothioxophosphorans (26) mit Diazomethan zuganglich ist. Bei der thermischen Reaktion von 1 und Trimethylsilylazid (30) wird hingegen das λ5-Thiaphosphiran 31 erhalten. Verbindungen dieses Typs (31, 32) sind auch durch Schwefelung der entsprechenden Iminomethylenphosphorane zuganglich. – Die Rontgenstrukturanalyse des durch partielle Hydrolyse von 4 erhaltenen Δ2-Diazaphospholens 5 wird angegeben, und die NMR-Daten sowie der Zerfall der Di- und Triazaphospholene werden diskutiert.
λ5-Di- and -Triazaphospholines – Synthesis, Isomerization, and Decomposition
The reaction of amino[(trimethylsilyl)methylene]thioxophosphorane 1 with diazoalkanes leads to Δ1-diazaphospholines 3, 7, 11, and 12. These sensitive compounds are stabilized by 1,3-migration of a trimethylsilyl group, where 3 and 7 end in the Δ2-diazaphospholines 4 and 8 and 11 and 12 decompose by [1 + 4]cycloreversion to give the azines 14 and 15 as well as aminothioxophosphane intermediate 13. 13 could be trapped by reaction with diazoalkanes as aminomethylenethioxophosphoranes (18 and 19). The corresponding phosphane system 20 and 21 is available by reduction of 18 and 19, respectively, with triphenylphosphane. tert-Butyl azide (22) and 1 form triazaphospholine 23, which isomerizes thermally by silyl migration to give 24. Photochemically induced elimination of N2 leads to the λ5-azaphosphiridine 25; this system is also accessible by reaction of aminoiminothioxophosphorane 26 with diazomethane. In contrast, thermal reaction of trimethylsilyl azide (30) and 1 results in a λ5-thiaphosphirane 31. Compounds of this type (31, 32) can also be synthesized by [1 + 2]cycloaddition of sulfur and the corresponding iminomethylenephosphorane. – The X-ray structure analysis of the Δ2-diazaphospholine 5 is described, NMR data and decomposition of di- and triazaphospholines are discussed.
19 citations
18 citations
TL;DR: In this paper, the formation of the 4th group hexaiodometallates was investigated by DTA and the thermal stability of the complex salts was determined, and it was shown that Rb 2 OsBr 6 was synthesized in a similar way from the corresponding bromine compounds.
16 citations
TL;DR: In this paper, the structures of 1-3 were determined from single crystal X-ray data, and the structure of 2-3 Te(II) exhibits a square planar coordination and Te-I bond lengths were found to be 260.7 (mean), 275.3, and 298.5 pm.
Abstract: The compounds [(C₆H₅)₄As]₂ TeCl₄ (1), [(C₂H₅)₄ N]₂ TeBr₄ · CH₃CN (2), and [(C₂H₅)₄N]₂TeI₄ (3) were prepared by the reaction of Te, X₂ , and excess (C₂H₅)₄NX (X = Br, I) in acetonitrile solution or by heating of [(C₆H₅)₄ As]₂TeCl₆ , Te, and (C₆H₅)₄ ASCl for several hours in the same solvent.The structures of 1-3 were determined from single crystal X-ray data.1 crystallizes in the monoclinic space group P2₁/n with a = 1061.8(2), b = 1614.2(3), c = 1341.7(3) pm, β = 94.21° and Z = 2; 2: tetragonal, P4/mmm, a = 1039.7(2), c = 690.5(1), Z = 1; 3: tetragonal, I4/mmm, a = 1061.7(2), c = 1342.8(4), Z = 2. In 1-3 Te(II) exhibits a square planar coordination. The Te -CI, Te -Br, and Te-I bond lengths were found to be 260.7 (mean), 275.3, and 298.5 pm, respectively.
12 citations
TL;DR: In this paper, a crown compound of 18C6 with amidosulfuric acid was obtained from reaction of the crown ether with methanol and ethanol, and the structure of the substance was elucidated with X-ray diffraction and IR data.
Abstract: Durch Umsetzung des Kronenethers 18C6 (1) mit Amidoschwefelsaure (2) in Wasser, Methanol und Ethanol konnte die Titelverbindung (3) dargestellt werden. Die Struktur der Substanz wurde durch Rontgenstrukturanalyse und durch ihr IR-Spektrum aufgeklart. Die beiden Komponenten von 3 sind durch drei Sauerstoff-Wasserstoff-Brucken miteinander verknupft. 3 eignet sich hervorragend fur die Isolierung und die Ruckgewinnung von 1 aus wasrigen Losungen.
18C6 Crown Complex of Amidosulfuric Acid
The title compound (3) has been obtained from reaction of the crown ether 18C6 (1) with amidosulfuric acid (2) in water, methanol, and ethanol. The structure of the substance was elucidated with X-ray diffraction and IR data. The two constituents of 3 are connected through three oxygen-hydrogen bridges. 3 is ideally suited for the isolation and recovery of 1 from aqueous solutions.
9 citations
Journal Article•
TL;DR: In this article, the authors describe a scenario where cristallise dans P2 1 /n avec Z=2; affinement jusqu'a R=0,065.
Abstract: Preparation et etude RX de [(C 6 H 5 ) 4 As] 2 TeCl 4 (1), [(C 2 H 5 ) 4 N] 2 TeBr 4 •CH 3 CN (2) et [(C 2 H 5 ) 4 N] 2 TeI 4 (3). (1) cristallise dans P2 1 /n avec Z=2; affinement jusqu'a R=0,065. (2) cristallise dans P4/mmm avec Z=1; affinement jusqu'a R=0,057. (3) cristallise dans I4/mmm avec Z=2; affinement jusqu'a R=0,054
9 citations
TL;DR: On varying reaction conditions, HgCl2 with ethane-1,2-dithiolate and Ph4PBr in methanol yields either [Ph4P]2[Hg3(SCH2CH2S)4] containing isolated trinuclear anions or [Ph 4P] 2 [Hg2[SCH 2 CH2S]3] with polymeric anions composed of quasi-isolated binuclear subunits as discussed by the authors.
Abstract: On varying the reaction conditions, of HgCl2 with ethane-1,2-dithiolate and Ph4PBr in methanol yields either [Ph4P]2[Hg3(SCH2CH2S)4] containing isolated trinuclear anions or [Ph4P]2[Hg2(SCH2CH2S)3] with polymeric anions composed of quasi-isolated binuclear subunits; both mercury thiolates may reflect characteristic structural features of biologically active species.
9 citations
Journal Article•
TL;DR: In this article, the structure of PN P-SSNO and of the product obtained on treating the perthionitrite with triphenylphosphane in acetonitrile, have been elucidated through X-ray diffraction and independently from new chemical and NMRspectrometric arguments.
Abstract: Sulfur, Nitrite, Thionitrites, Nitrososulfides, Bis(triphenylphosphine)iminium Salts As a major product from the reaction of PNP-nitrite [P = P(C6H 5)3] with elementary sulfur o ra PNP-polysulfide (PN P)2S12 in acetone under anaerobic conditions PNP-perthionitrite (PNPnitrosodisulfide) PNP-SSNO has been isolated. VIS/UV-spectra point to a thionitrate or perthionitrate as a precursor. The structures of PN P-SSNO and of the product obtained on treating the perthionitrite with triphenylphosphane in acetonitrile, PN P-SN O (PNP-m onothionitrite, PNP-nitrososulfide), have been elucidated through X-ray diffraction and independently from new chemical and NMRspectrometric arguments. PN P-SSN O crystallizes in the orthorhombic space group P ben with a = 11.843(3), b = 16.647(5), c = 15.556(4) Ä , PN P-SN O in the triclinic group P I with a = 10.525(3), b = 17.196(5), c = 9.451(3) Ä , a = 95.22(3), ß = 92.32(3), y = 91.65(3)°.
TL;DR: The configurations of the mitosane derivatives described in the previous communications1) were established by spectroscopic investigations and X-ray analysis of rac-1e as discussed by the authors, and they were used in the synthesis of Mitomycins.