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  • 1
    ISSN: 0044-2313
    Keywords: Phosphoraneiminato Complexes ; Boron Compounds ; Crystal Structures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Phosphoraneiminato Complexes of Boron. Syntheses and Crystal Structures of [BBr2(NPMe3)]2, [B2Br3(NPiPr3)2]Br, [B2(NPEt3)4]Br2, [B2Br2(NPPh3)3]BBr4 and [{B2(NMe2)2}2(NPEt3)2]ClThe bromoderivatives of the title compounds are prepared from the corresponding silylated phosphoraneimines Me3SiNPR3 and boron tribromide. The boron subcompound [{B2(NMe2)2}2(NPEt3)2]Cl2 derives from Me3SiNPEt3 and B2Cl2(NMe2)2. All complexes are characterized by NMR and IR spectroscopy as well as by crystal structure determinations.[BBr2(NPMe3)]2 (1): Space group P21/n, Z = 2, R = 0.031. Lattice dimensions at -50°C: a = 723.8, b = 894.2, c = 1305.4 pm, β = 92.35°. 1 forms centrosymmetric molecules in which the boron atoms are linked via μ2-N bridges of the NPMe3- groups of from B2N2 four-membered rings with B—N distances of 149.9 and 150.9 pm.B2Br3(NPiPr3)2]Br (2): Space group P21, Z = 2, R = 0.059. Lattice dimensions at -80°C: a = 817.6, b = 2198.7, c = 851.5 pm, β = 115.09°. In the cations of 2 the boron atoms are lined via the μ2-N atoms of the NPiPr3- groups to form planar, asymmetric B2N2 four-membered rings with B—N distances of 143 and 156 pm.[B2(NPEt3)4[Br2·4CH2Cl2 (3): Space group C2/c, Z = 4, R = 0.042. Lattice dimensions at -50°C: a = 1946.1, b = 1180.3, c = 2311.3 pm, β = 101.02°. The structure contains centrosymmetric dications in which both the boron atoms are lined by the N atoms of two of the NPEt3- groups to form a B2N2 four-membered ring with B—N distances of 149.6 pm. The remaining two NPEt3- groups are terminally bonded with very short B—N distances of 133.5 pm.B2Br2(NPPh3)3]BBr4 (4): Space group P1, Z = 2, R = 0.065. Lattice dimension at -50°C: a = 1025.7, b = 1496.1, c = 1807.0 pm, α = 85.09°, β = 82.90°, γ = 82.72°. In the cation the boron atoms are lined via the μ2-N atoms of two of the NPPh3- groups to form a nearly planer B2N2 four-membered ring with B—N distances of 149.3-153.1 pm. The third NPPh33 group is terminally connected with teh sp2 hybridized boron atom and with a B—N distance of 134.1 pm along with an almost linear BNP bond angle of 173.6°.[{B2(NMe2)2}2(NPEt2)2]Cl2 · 3CH2Cl2 (5): Space group C2/c, Z = 4, R = 0.098. Lattice dimensions at -70°C: a = 1557.9, b = 1294.7, c = 2122.9 pm, β = 96.08°. The structure of 4 contains centrosymmetric dications in which two by two B-B dumb-bells are linked via the μ2-N atoms of the two NEPt3- groups to form B4N2 six-membered rings with B—N distances of 150 and 156 pm and B-B distances of 173 pm. The B—N distances of the terminally bonded NMe2- groups correspond to 138 pm double bonds.
    Notes: Die Bromoderivate der Titelverbindungen werden aus den entsprechenden silylierten Phosphaniminen Me3SiNPR3 und Bortribromid hergestellt. Die Borsubverbindung [{B2(NMe2)2}2(NPEt3)2]Cl2 entsteht aus Me3SiNPEt3 und B2Cl2(NMe2)2. Alle Komplexe werden durch NMR- und IR-Spektren sowie durch Kristallstrukturanalysen charakterisiert.[BBr2(NPMe3)]2 (1): Raumgruppe P21/n, Z = 2, R = 0,031. Gitterkonstanten bei -50°C: a = 723,8; b = 894,2; c = 1305,4 pm; β = 92,35°. 1 bildet zentrosymmetrische Moleküle, in denen die Boratome über μ2-N-Brücken der NPMe3--Gruppen zu B2N2-Vierringen mit B—N-Abständen von 149,9 und 150,9 pm verknüpft sind.[B2Br3(NPiPr3)2]Br (2): Raumgruppe P21, Z = 2, R = 0,059. Gitterkonstanten bei -80°C: a = 817,6; b = 2198,7; c = 851,5 pm; β = 115,09°. In den Kationen von 2 sind die Boratome über die μ2-N-Atome der NPiPr3--Gruppen zu planaren, asymmetrischen B2N2-Vierringen mit B—N-Abständen von 143 und 156 pm verknüpft.[B2(NPEt3)4]Br2 · 4 CH2Cl2 (3): Raumgruppe C2/c, Z = 4, R = 0,042. Gitterkonstanten bei -50°C: a = 1946,1; b = 1180,3; c = 2311,3 pm; β = 101,02°. Die Struktur enthält zentrosymmetrische Dikationen, in denen die N-Atome zweier NPEt3--Gruppen die beiden Boratome zu einem B2N2-Vierring mit B—N-Abständen von 149,6 pm verknüpfen. Die beiden übrigen NPEt3--Gruppen sind terminal gebunden mit sehr kurzen B—N-Abständen von 133,5 pm.[B2Br2(NPPh3)3]BBr4 (4): Raumgruppe P1, Z = 2, R = 0,065. Gitterkonstanten bei -50°C: a = 1025,7; b = 1496,1; c = 1807,0 pm; α = 85,09°; β = 82,90°; γ = 82,72°. In dem Kation sind die Boratome über die μ2-N-Atome zweier NPPh3--Gruppen zu einem nahezu planaren B2N2-Vierring mit B—N-Abständen von 149,3-153,1 pm verknüpft. Die dritte NPPh3--Gruppe ist mit dem sp2-hybridisierten Boratom terminal mit einem B—N-Abständ von 134,1 pm verbunden bei einem fast linearen BNP-Bindungswinkel von 173,6°.[{B2(NMe2)2}2(NPEt3)2]Cl2 · 3 CH2Cl2 (5): Raumgruppe C2/c, Z = 4, R = 0,098. Gitterkonstanten bei -70°C: a = 1557,9; b = 1294,7; c = 2122,9 pm; β = 96,08°. Die Struktur von 4 enthält zentrosymmetrische Dikationen, in denen je zwei B—B-Hanteln über die μ2-N-Atome der beiden NPEt3--Gruppen zu B4N2-Sechsringen mit B—N-Abständen von 150 und 156 pm sowie B—B-Abständen von 173 pm verknüpft sind. Die B—N-Abstände der terminal gebundenen NMe2--Gruppen entsprechen mit 138 pm Doppelbindungen.
    Additional Material: 5 Ill.
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  • 2
    ISSN: 0044-2313
    Keywords: [Dibenzo-18crown6] · CH3CN · CH3CSOH ; [Dicyclohexyl-18-crown6] · (CH3CSOH)2 ; [Cs(benzo-15crown5)2] CH3CSS ; [Cs(dibenzo-18crown6)]2S5(DMF)2 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Crystal Structure of the Adducts [DB-18C6] · CH3CN · CH3CSOH and [DC-18C6](CH3CSOH)2 as well as of the Salt-like Compounds [Cs(B-15C5)2]CH3CSS and [Cs(DB-18C6)]2S5(DMF)21)The reaction products of crown ethers, cesium, and sulfur in aprotic solvents like acetonitrile and dimethylformamide strongly depend on the reaction conditions. Using CH3CN as a solvent, sometimes neutral host-guest adducts crystallize only, e.g., [dibenzo-18C6] · CH3CN · CH3CSOH (monoclinic, S. G. P21/c, Z = 4, a = 9.73(1) Å, b = 22.03(1) Å, c = 11.86(1) Å, β = 91.8(1)°) or [dicyclohexyl-18C6](CH3CSOH)2 (monoclinic, S. G. P21/n, Z = 2, a = 7.75(1) Å, b = 10.32(1) Å, c = 17.73(1) Å, β = 95.7(1)°). The monothioacetic acid, CH3CSOH, must be regarded as the first product of the hydrolysis of CH3CN. Furthermore, another product of this kind of hydrolysis, CH3CSSH, is obtained too. Therefore, we also obtain the salt-like compound [Cs(benzo-15C5)2]CH3CSS (monoclinic, S. G. C2/c, Z = 4, a = 16.05(1) Å, b = 16.73(1) Å, c = 13.11(1) Å, β = 106.3(1)°). If the solvent DMF is used, the pentasulfide [Cs(dibenzo-18C6)]2S5(DMF)2 crystallizes (monoclinic, S. G. P21/n, Z = 4, a = 14.79(1) Å, b = 14.24(1) Å, c = 25.74(1) Å, β = 92.7(1°. The S52- anions show the cis-conformation.
    Notes: Setzt man Kronenether mit Cs2CO3 im Molverhältnis 2:1 mit Schwefel und H2S in Dimethylformamid oder Acetonitril als Lösungsmitteln um, erhält man je nach Reaktionsführung und Lösungsmittel unterschiedliche Produkte. Mit Dibenzo-18-Krone-6 in CH3CN kristallisiert das neutrale 1:2-Addukt [Dibenzo-18C6] · CH3CSOH · CH3CN (monoklin, Raumgruppe P21/c, Z = 4; a = 9,73(1) Å; b = 22,03(1) Å; c = 11,86(1) Å; β = 91,8(1)°). Mit Dicyclohexyl-18-Krone-6 in CH3CN erhalten wir unter ähnlichen Bedingungen das neutrale 1:2-Addukt [Dicyclohexyl-18C6](CH3CSOH)2 (monoklin, Raumgruppe P21/n; Z = 2; a = 7,75(1) Å; b = 10,32(1) Å; c = 17,73(1) Å; β = 95,7(1)°). Mit Benzo-15-Krone-5 in CH3CN erhalten wir unter wiederum nicht wesentlich unterschiedlichen Bedingungen das Dithioacetat [Cs(Benzo-15C5)2]CH3CSS, das ein komplexes Kronenether-Kation aufweist (monoklin, Raumgruppe C2/c; Z = 4; a = 16,05(1) Å; b = 16,73(1) Å; c = 13,11(1) Å; β = 106,3(1)°). Wird Dibenzo-18-Krone-6 in DMF umgesetzt, kristallisiert das Pentasulfid [Cs(Dibenzo-18C6)]2S5(DMF)2 (monoklin, Raumgruppe P21/n; Z = 4; a = 14,79(1) Å; b = 14,24(1) Å; c = 25,74(1) Å; β = 92,7(1)°). Die Pentasulfid-Anionen sind cis-konformiert.
    Additional Material: 4 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 28 (1990), S. 205-211 
    ISSN: 0749-1581
    Keywords: Tetramethyllimonene ; Assignments ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dynamic effects of tetramethyllimonene were studied at low temperatures. Nuclear Overhauser effects measured under optimized conditions at 223 K and the results of 2D correlation experiments allowed the identification of two conformers and the assignment of all the proton and carbon resonances. For the determination of exchange and relaxation rates the method of saturation transfer was applied. At temperatures below 223 K further dynamic effects were recognized. Structural information obtained experimentally was compared with the results of Allinger force field calculations.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 30 (1992), S. 466-475 
    ISSN: 0749-1581
    Keywords: Heteronuclear NOE ; Selective pulses ; Shaped pulses ; Sequential excitation ; Improved data accumulation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An improved 1D pulse sequence for detecting heteronuclear NOEs on a qualitative level is described and demonstrated. It makes use of shaped selective pulses and takes advantage of sequential perturbation of several proton resonances during one experiment and correspondingly more efficient data accumulation schemes. The method is particularly suitable for assigning quaternary carbons and for establishing connectivities between assigned molecular fragments bound to these quaternary centres.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 29 (1991), S. 834-847 
    ISSN: 0749-1581
    Keywords: Cembrenenol ; Cyclic diterpene ; Conformational analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The solution structure of the cyclic diterpene cembrenenol was investigated. A strategy for conformational analysis is proposed which is based on computational methods and experiments to determine the structure-relevant NMR parameters. Computed and experimentally determined steady-state NOEs were compared in a first step, which served to sort out a few probable conformers. The detailed analysis of homo- and hetero-nuclear coupling information together with NOE data defining local geometries allowed, in a second step, the selection of the most probable conformation. The structure corresponds to the lowest energy structure proposed by computational methods alone. Its ring structure is in excellent agreement with the x-ray ring structure of the closely related cembrenene.
    Additional Material: 6 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 34 (1901), S. 2794-2799 
    ISSN: 0365-9496
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 15 (1882), S. 49-50 
    ISSN: 0365-9496
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 15 (1882), S. 812-813 
    ISSN: 0365-9496
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 39 (1906), S. 2018-2022 
    ISSN: 0365-9496
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 38 (1905), S. 2203-2207 
    ISSN: 0365-9496
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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