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Fully Chlorinated N-Silyl Amides of Titanium and Tungsten - Crystal Structure of Cl3SiNW(Cl3)N(SiCl3)2 (1997)

Schwarze, Bernd ; Milius, Wolfgang ; Schnick, Wolfgang

Weinheim : Wiley-Blackwell

Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 701-704

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ISSN: 0009-2940

Keywords: N-Silyl amides ; Precursor ; 14N-NMR ; Titanium ; Tungsten ; Chemistry ; Inorganic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The reaction of hexachlorodisilazanyllithium (Cl3Si)2NLi (1), with TiCl4 leads selectively to the novel fully chlorinated amides (Cl3Si)2NTiCl3 (2) or [(Cl3Si)2N]2 TiCl2 (3), respectively, depending on the molar ratio of the starting materials. The analogous reaction of 1 with WCl6 yielded the amide imide Cl3SiN=W(Cl3)N(SiCl3)2 (5) by elimination of SiCl4. The relative amounts of the starting materials had no effect on the formation of 5. 14/15N- and 29Si-NMR data on the starting materials and products show significantly different effects, when compared with those of analogous N-trimethylsilyl derivatives, due to the lower energy of the electrons in the N—Si and N—M ß bonds. The crystal structure of 5 (triclinic, space group P1) was determined by X-ray structure analysis.

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/cber.19971300605

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Multinuclear magnetic resonance study of N,N′,N″-tris(trimethylsilyl)borazine (1995)

Wrackmeyer, Bernd ; Schwarze, Bernd ; Durran, D. Michael ; [et al.]

Chichester : Wiley-Blackwell

Organic Magnetic Resonance 33 (1995), S. 557-560

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ISSN: 0749-1581

Keywords: NMR ; 14N NMR ; 11B NMR ; borazines ; coupling constants 1J(29Si14N),1J(14N11B) ; coupling signs ; 14N electric field gradient ; Chemistry ; Analytical Chemistry and Spectroscopy

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The nuclear spin relaxation rate of the quadrupolar 14N nuclei in N,N′,N″-tris(trimethylsilyl)borazine (1) is surprisingly slow [T1(14N)=0.1 s]. This allows one to measure 1J(29Si14N) (9.6 Hz) directly from the 29Si NMR spectra and also to compare signs of coupling constants 1J(29Si14N) (〈0) and 3J(14NSiC1H) (〉0) by 2D 29Si/1H HETCOR experiments. Since the transverse relaxation time T2(14N) in 1 is governed by scalar relaxation of the second kind, the magnitude of 1J(14N11B) can be evaluated (23 ± 0.5 Hz). 11B, 14N and 29Si NMR data for N,N′-bis(trimethylsilyl)borazine (2) were also obtained, and 11B and 14N NMR spectra of the parent borazine [HBNH]3 (3), and of [HBNMe]3 (4) were remeasured. Calculation of the tensor components of the 14N electric field gradient shows that eqzz in 1 and in 2 for 14N(Si) is significantly smaller than for other borazines [HBNR]3, e.g. with R=H (3) or Me (4), in agreement with the experimental results.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/mrc.1260330711

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Reaction of Hexamethyldisilazane with Borane in Tetrahydrofuran (1996)

Wrackmeyer, Bernd ; Schwarze, Bernd

Weinheim : Wiley-Blackwell

Zeitschrift für anorganische Chemie 622 (1996), S. 2048-2052

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ISSN: 0044-2313

Keywords: Borane ; diborane ; borazine ; NMR spectroscopy ; Chemistry ; Inorganic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Description / Table of Contents: Reaktion von Hexamethyldisilazan mit Boran in TetrahydrofuranHexamethyldisilazan 1 reagiert mit Boran in Tetrahydrofuran (THF—BH3, 2) zunächst unter Bildung des Addukts (Me3Si)2NH—BH3 (3), das dann entweder in N,N-Bis(trimethylsilyl)-μ-aminodiboran(6) 5 oder in eine Mischung aus 5 und N-Trimethylsilyl-μ-aminodiboran(6) 6 übergeht, abhängig von den Reaktionsbedingungen. Die Verbindungen 5 und 6 lassen sich quantitativ in das N,N′,N″-Tris(trimethylsilyl)borazin 4 überführen. Dabei werden drei Zwischenstufen identifiziert, nämlich N,N-Bis(trimethylsilyl)aminoboran 7, N,N-Bis(trimethylsilyl)amino(N′-trimethylsilylamino)boran 8 und N-Trimethylsilylaminoboran-Trimer 9. Alle Produkte und Zwischenstufen wurden mittels Multikern-NMR-Spektroskopie charakterisiert, und Kopplungskonstanten 1J(29Si, 15N) in 5 und 6 wurden mit der Hahn-echo extended (HEED) INEPT Pulssequenz in den 29Si NMR Spektren bestimmt.

Notes: Hexamethyldisilazane 1 reacts with borane in tetrahydrofuran (THF—BH3, 2) first by formation of an adduct (Me3Si)2NH—BH3 (3), and then either to the N,N-bis-(trimethylsilyl)-μ-aminodiborane 5 or to the mixture of 5 and N-trimethylsilyl-μ-aminodiborane(6) 6, depending on the reaction conditions. The compounds 5 and 6 can be quantitatively converted to the N,N′,N″-tris(trimethylsilyl)borazine 4. Three intermediates can be identified, namely N,N-bis(trimethylsilyl)borane 7, N,N-bis(trimethylsilyl)amino(N′-trimethylsilylamino)borane 8 and N-trimethylsilylaminoborane-trimer. All products and intermediates were characterized by multinuclear NMR spectroscopy, and coupling constant 1J(29Si, 15N) were measured from 29Si NMR spectra by using the Hahn-echo-extended (HEED) INEPT pulse sequence.

Additional Material: 3 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/zaac.19966221208

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