Showing papers by "Bernt Krebs published in 1992"
••
67 citations
••
TL;DR: The first quarternary thioborate LiSrB3S6 was reported in this paper, which contains isolated B3S2 3-anions with three exocyclic sulfur atoms, and the crystal data for the first isotypic metathioborates are: space group Cc; a = 14.933(6), b = 8.703(4), c = 7.512(1), 8.424(3, 8.804(1) A, β = 116.76(3)°.
Abstract: The thioborates M3B3S6 (M = Na1,2, K1,2, Rb) and LiSrB3S6 were prepared from stoichiometric amounts of the metal sulfides, boron and sulfur. The crystal data for the isotypic M3B3S6, (M = Na, K, Rb) compounds are: space group R3c; a = 15.118(1), 15.520(5), 15.813(4) A; c = 7.512(1), 8.424(3), 8.804(1) A (hexagonal). The crystal data for the first quarternary thioborate LiSrB3S6 are: space group Cc; a = 14.933(6), b = 8.703(4), c = 7.866(3) A, β = 116.76(3)°. All four metathioborates contain isolated B3S2 3- anions which form B3S3 rings with three exocyclic sulfur atoms.
32 citations
••
TL;DR: In this article, X-ray diffraction studies on 5a and 5b indicate a delicate charge balance in the bonding system of 1H-1,2,4,σ2-diazaphospholes under the influence of the exocyclic push/pull substituents iPr2N and CF3 or CO2Me, respectively.
Abstract: Reactive E = C(p—p)π Systems, XXXII[1]. — First Representatives of Amino-Substituted 1,2,4-Diazaphospholes
(Diisopropylamino)phosphaethyne iPr2N—C≡P reacts at 20° C in a [3 + 2] cycloaddition with (trifluoromethyl)diazomethane (2a) or methyl diazoacetate (2b) to yield a mixture of the corresponding regioisomers 1H-1,2,4-diazaphospholes (5a or 5b) and 1H-1,2,3-diazaphospholes (6a or 6b) in quantitative yields (isomer ratio: 5a/6a = 2:1; 5b/6b = 4:1). X-ray diffraction studies on 5a and 5b indicate a delicate charge balance in the bonding system of 1H-1,2,4,σ2-diazaphospholes under the influence of the exocyclic push/pull substituents iPr2N and CF3 or CO2Me, respectively.
24 citations
••
TL;DR: Purple acid phosphatase from red kidney bean has been crystallized from ammonium sulfate solutions in the pH range from 3.5 to 5.5 and the crystal form is tetragonal bipyramidal and the largest crystals grew up to 2.0 mm long.
23 citations
••
19 citations
••
18 citations
••
18 citations
••
TL;DR: In this paper, the reactions of 1:1:1 molar ratio mixtures of NaSPh/MnCl 2 /Et 4 NBr and NaSph/CoCl 2/Et 6 Cl 4 NCl in methanol afford the compounds [Et4 N] 4 °Mn(SPh) 3 Br] (1) and [Eb 4 N] 2 °Co 4 (SPh(6 Cl 4 ).MeCN (2), respectively, with the following crystal data: space group P2 1 /c for
Abstract: The reactions of 1:1:1 molar ratio mixtures of NaSPh/MnCl 2 /Et 4 NBr and NaSPh/CoCl 2 /Et 4 NCl in methanol afford the compounds [Et 4 N] 4 °Mn(SPh) 3 Br][Mn(SPh) 3 Cl] (1) and [Et 4 N] 2 °Co 4 (SPh) 6 Cl 4 ].MeCN (2), respectively, with the following crystal data: space group P2 1 /c for 1, and space group P2 1 /c for 2.
15 citations
••
15 citations
••
TL;DR: The use of mass spectrometers for the analysis of transition metal complexes is demonstrated by combined high resolution Plasma Desorption Mass Spectrometry (PDMS) and Secondary Ion Mass Spectraletry (SIMS) investigations of the neutral nickel thiolate complexes as mentioned in this paper.
Abstract: The use of mass spectrometry for the analysis of transition metal complexes is demonstrated by combined high resolution Plasma Desorption Mass Spectrometry (PDMS) and Secondary Ion Mass Spectrometry (SIMS) investigations of the neutral nickel thiolate complexes [Ni₄(SC₃H₇)8] (1), [Ni₄(SC₆H₁₁)8] (2), [Ni₈(SCH₂COOEt)₁₆] (3) and [Ni₆(SC₃H₇)₁₂] (4). The positive spectra are dominated by three kinds of SI-species: (a) molecular ions, (b) fragment ions and (c) molecular ions with one or more substrate atoms attached. The negative spectra show mainly nickel sulfur cluster ions of the composition (NiₓSy)⁻. In contrast to many Fast Atom Bombardment (FAB) spectra of neutral metal complexes, SIMS and PDMS spectra provide molecular weight as well as fragment ion information. Both techniques are most powerful tools for the investigation of coordination compounds because the samples are easy to prepare and the spectra are independent of matrix conditions. Additionally crystallographic studies have been carried out for 4. The hexanuclear complex 4 with square planar Ni-S coordination sites crystallizes in the trigonal space group R 3 with Z = 3 and α = 18.537(5), c = 13.966(3) A.
13 citations
••
••
TL;DR: The photochemical reaction of the azidophosphane (iPr2N)2PN3 (1) with the tetraazaphospholene (3) and bis(imino)phosphorane (Me3Si)2NP(NSiMe3)2 (6) proceeds by elimination of N2 to yield (5) and by 1,3-silyl group shift to furnish (8) the structures of which were determined by means of NMR data and, in the case of 5, additionally by X-ray structure
Abstract: 1,2-Dihydro-1,3,2λ5,4λ5-diazadiphosphete – Synthesis, Structure and Isomerization to the „Inner Salt” of 1,3,2,4λ5-Diazadiphosphetan-2-ium Hydroxide
The photochemical reaction of the azidophosphane (iPr2N)2PN3 (1) with the tetraazaphospholene (3) and the bis(imino)phosphorane (Me3Si)2NP(NSiMe3)2 (6) proceeds by elimination of N2 to yield (5) and by 1,3-silyl group shift to furnish (8) the structures of which were determined by means of NMR data and, in the case of 5, additionally by X-ray structure analysis.
••
••
••
TL;DR: In this paper, a polymeric anion was isolated from a saturated solution of TeCl4 in conc. HCl/H2O with the formal composition HTe2Cl9 · 4H 2O (1) (space group C2/c, a = 11.642(6), b = 13.012(4), c = 12.663(5) Å, β = 119.64(3)° at 140 K).
Abstract: Light yellow needles of crystalline nonachloroditellurous acid with the formal composition HTe2Cl9 · 4H2O (1) (space group C2/c, a = 11.642(6), b = 13.012(4), c = 12.663(5) Å, β = 119.64(3)° at 140 K) were isolated from a saturated solution of TeCl4 in conc. HCl. From a solution of more diluted HCl the acid HTeCl4OH · 5H2O (2) could be prepared (space group P212121, a = 7.065(3), b = 8.551(2), c = 18.192(6)Å at 140 K). 1 is the first acid isolated from the system TeCl4 /HCl/H2O with a polymeric anion. The novel polynuclear [Te2Cl9]nn- chains are built from alternately corner-sharing and edge-sharing distorted octahedral TeCl6 units. The mean bond distances are 2.356 Å for terminal Te-Cl and 2.805 Å for Te-μ2Cl. 2 contains square-pyramidal [TeCl4OH]- anions with oxygen in the apical position (Te-Cl: 2.447-2.552 Å; Te-O: 1.926 Å). The cations in both structures are [H9O4]+ hydroxonium ions (O···O (1): 2.47(3), 2.55(2) and 2.57(1) Å; O···O (2): 2.550(4), 2.584(4) and 2.588(5) Å). Thus the formulae of the acids have to be written as [H9O4]n[Te2Cl9]n and [H9O4][TeCl4OH] · H2O. Raman spectra of both compounds are reported.
••
TL;DR: In this article, a number of ligands of the type (Me2PCH2CH2)2SiX2 and (2-Me2PC6H4)SiXMe2 (X = F, Cl) were characterized by analytical (C, H) and spectroscopic investigations (MS, IR, NMR) charakterisiert.
Abstract: Donor/Akzeptor-Liganden des Typs (Me2PCH2CH2)2SiX2 und (2-Me2PC6H4)SiXMe2 (X = F, Cl) reagieren mit [Rh(CO)2Cl]2 (1) zu den Einkernkomplexen RhCl(CO)(Me2PCH2CH2)2SiX2 [X = F(4), Cl (5)] bzw. RhCl(CO)[(2-Me2PC6H4)SiXMe2]2 [X = F(8), Cl (9)]. Bei den Liganden (Me2PCH2CH2)2SiCl2 (3) und (2-Me2PC6H4)SiCMe2 (7) treten als Folgeprodukte der primar gebildeten Rh(I)-Komplexe durch oxidative Addition von SiCl Rhodium(III)-Verbindungen geringer Loslichkeit auf. Nur im Fall von 8 geben die Koordinationsverschiebungen Δδ = δ(Komplex)−δ(Ligand) und Kopplungskonstanten Hinweise auf mogliche RhSi-Wechselwirkungen. Die durch Rontgenbeugung ermittelte Molekulstruktur von 8 zeigt allerdings keine RhSi- oder RhF-Bindungskontakte. – Die neuen Verbindungen wurden durch analytische (C, H) und spektroskopische Untersuchungen (MS, IR, NMR) charakterisiert.
Alternative Ligands. XXIII Rhodium(I) Complexes with Donor/Acceptor Ligands of the Type (Me2PCH2CH2)2SiX2 and (2-Me2PC6H4)SiXMe2 (X = F, Cl)
Donor/acceptor ligands of the type (Me2PCH2CH2)2SiX2 and (2-Me2PC6H4)SiXMe2 (X = F, Cl) react with [Rh(CO)2Cl]2 (1) to give the mononuclear complexes RhCl(CO)(Me2PCH2CH2)2SiX2 [X = F(4), Cl (5)] and RhCl(CO)[2-Me2PC6H4)SixMe2]2 [X = F (8), Cl (9)], respectively. In case of the ligands (Me2PCH2CH2)2SiCl2 (3) and (2-Me2PC6H6)SiClMe2 (7) the Rh(I) complexes formed in the first step partly undergo oxidative addition reactions of SiCl bonds yielding rhodium(III) compounds of low solubility. Only for 8 the coordination shifts Δδ = δ(complex)−δ(ligand) and coupling constants give some indication to possible RhSi interactions. However, the molecular structure of 8 determined by X-ray diffraction does not show RhSi or RhF bonding contacts. The new compounds were characterized by analytical (C, H) and spectroscopic investigations (MS, IR,-NMR).
••
TL;DR: In this article, the authors show that the NSi-Gruppierung is not suited for coordination because of strong (p-d)π-interaction, which is not suitable for coordination with strong (π-π)-interaction.
Abstract: Die Umsetzung von M(CO)4NBD (NBD = Norbornadien; M Cr, Mo, W) mit den Liganden Me2ESiMe2(CH2)2E′Me2 liefert fur E,E′ P, As die Chelatkomplexe (CO)4M[Me2ESiMe2(CH2)2E′Me 2], nicht jedoch fur E und/oder E′ N. Die NSi-Gruppierung ist wegen der starken (p-d)π-Ruckbindung nicht zur Koordination befahigt; im Fall der Liganden mit E P oder As und E′ N sind im Reaktionsgemisch zwar Chelatkomplexe nachweisbar, bei den isolierbaren Produkten handelt es sich jedoch um Komplexe mit zwei E-koordinierten Liganden. Die neuen Verbindungen werden durch analytische und spektroskopische (IR, NMR, MS) Untersuchungen charakterisiert. Die spektroskopischen Daten dienen auch der Beurteilung der Koordinations-eigenschaften der Liganden. Die Rontgenbeugungsanalyse der Molybdankomplexe (CO)4Mo[Me2ESiMe2(CH2) 2AsMe2] (E P, As) ergibt in Ubereinstimmung mit den Koordinationseffekten nur geringe Unterschiede zwischen SiE und CE-Donorfunktionen. – Bei Versuchen, die Liganden Me2ESiMe2(CH2)2AsMe2 (E P, As zur Synthese von Fe(CO)3L-Komplexen zu nutzen, werden unter Spaltung der SiE-Bindung die Zweikernsysteme Fe2(CO)6(EMe2)2(E P, As) und das Disilanderivat [Me2Si(CH2)2AsMe2]2 erhalten.
Alternative Ligands. XXVI. M(CO)4 L-Complexes (M Cr, Mo, W) of the Chelating Ligands Me2ESiMe2(CH2)2E′ Me2 (Me CH3; E P, As; E′ N, P, As)
The reaction of M(CO)4NBD (NBD = norbornadiene; M Cr, Mo, W) with the ligands Me2ESiMe2(CH2)2E′ Me2 yields the chelate complexes (CO)4M[Me2ESiMe2]) for E,E′ P, As, but not for E and /or E′ N. The NSi group is not suited for coordination because of strong (p-d)π-interaction. In the case of the ligands with E P or As and E′ N chelate complexes can be detected in the reaction mixture, but isolable products are complexes with two ligands coordinated via the E donor group. The new compounds are characterized by analytical and spectroscopic (IR, NMR, MS) investigations. The spectroscopic data are also used to deduce the coordinating properties of the ligands. X-ray diffraction studies of the molybdenum complexes (CO)4Mo[Me2ESiMe2(CH2)2AsMe 2] (E P, As) in accord with the observed coordination effects show only small differences between SiE and CE donor functions. Attempts to use the ligands Me2ESiMe2(CH2)2AsMe2 (E P, As) for the preparation of Fe(CO)3L complexes result in the fission of the SiE bonds and the formation of the binuclear systems Fe2(CO)6(EMe2)2 (E P, As) together with the disilane derivative [Me2Si(CH2)2AsMe2]2.
••
••
••