ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

Isotopically selective IR multiphoton dissociation of 1,3,5-trioxane (1996)

Churakov, V. ; Fuss, W.

Springer

Applied physics 62 (1996), S. 203-212

add to mindlist on the mindlist

Details

ISSN: 1432-0649

Keywords: 33.80.Wz

Source: Springer Online Journal Archives 1860-2000

Topics: Physics

Notes: Abstract Searching for oxygen-isotope selectivity, we investigated the infrared multiphoton dissociation of the formaldehyde trimer around 10 µm, in a range where the molecule has a degenerate and a non-degenerate CO stretch vibration and a degenerate CH2 deformation vibration. In the region of the two latter, the wavelength dependence of the dissociation yield exhibits sharp structures. They were assigned ton-photon resonances (n = 2, 3, 5) by the help of the IR spectrum in the fundamental and overtone region. The O and C selectivities were very small (1.05) near the non-degenerate CO stretch band, but surprisingly large (2–4) in the CH2 deformation, which has no isotopic shift. The selectivity is not controlled by the first (n-photon) excitation step, but only by a later step. Its assignment is attempted. The pressure dependence of the dissociation is peculiar: Only after an initial decrease, the yield exhibits the usual rise with pressure. We attribute the decrease to a relaxation which perturbs the two-photon resonance.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01081126

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

2

Electronic Resource

Nucleophilic Aromatic Substitution of Hydrogen in the Reaction of tert-Alkylamines with Nitrosobenzenes - Synthesis and NMR Study of N-(tert-Alkyl)-ortho-nitrosoanilines (1999)

Lipilin, Dmitriy L. ; Churakov, Aleksandr M. ; Ioffe, Sema L. ; [et al.]

Weinheim : Wiley-Blackwell

Liebigs Annalen 1999 (1999), S. 29-35

add to mindlist on the mindlist

Details

ISSN: 1434-193X

Keywords: Nitrosobenzenes ; ortho-Nitrosoanilines ; 2-Nitroso-1,3-phenylenediamines ; Nucleophilic aromatic substitution ; Oxidative nucleophilic substitution of hydrogen ; Chemistry ; General Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: -The reaction of primary amines bearing tertiary alkyl groups (e.g. R-NH2; R = tBu, 1-adamantyl) with nitrosobenzenes has been found to proceed by oxidative nucleophilic aromatic substitution of hydrogen, thereby affording N-(tert-alkyl)-ortho- and -para-nitrosoanilines. The replacement of hydrogen proceeds more rapidly than the replacement of ortho- or para-nitro or -bromo substituents. With p-nitronitrosobenzene, both ortho-hydrogen atoms are substituted to afford N,N′-di(tert-alkyl)-4-nitro-2-nitroso-1,3-phenylenediamines 8a,b. The addition of oxidizing agents (e.g. MnO2) increases the yield of products. 1H-, 13C-, 14N- and 15N-NMR studies have confirmed the structures of the compounds under investigation. In ortho-nitrosoanilines, the rotamer with the nitroso group syn to the amino group is favored.

Additional Material: 3 Tab.

Type of Medium: Electronic Resource

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

3

Electronic Resource

A Novel Route to the 5-[2-(Diphenylphosphanyl)ethyl]-1,2,3,4-tetramethylcyclopentadienyl Ligand - Synthesis and Crystal Structure of [η5:η1-C5(CH3)4CH2CH2PPh2]ZrCl3·THF (1999)

Krut'ko, Dmitrii P. ; Borzov, Maxim V. ; Veksler, Eduard N. ; [et al.]

Weinheim : Wiley-Blackwell

Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 1973-1979

add to mindlist on the mindlist

Details

ISSN: 1434-1948

Keywords: Phosphanylethyl-functionalized cyclopentadienyl ligands ; Intramolecular coordination ; Spiro compounds ; Zirconium ; Chemistry ; General Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The five-step synthesis of the first transition metal complex with the C5(CH3)4CH2CH2PPh2 ligand [η5:η1-C5(CH3)4CH2CH2PPh2]ZrCl3·THF (11), starting from the known compound [2-(dimethylamino)ethyl]tetramethylcyclopentadiene (4) via 4,5,6,7-tetramethylspiro[2,4]hepta-4,6-diene (7), is reported. Lithium cyclopentadienide LiC5(CH3)4CH2CH2PPh2 (9), silylated cyclopentadiene (CH3)3SiC5(CH3)4CH2CH2PPh2 (10) and cyclopentadiene HC5(CH3)4CH2CH2PPh2 (12) were isolated and characterised as pure substances. The crystal structure of the zirconium complex 11 was established by X-ray diffraction analysis.

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

4

Electronic Resource

Synthesis of Germatranyl Derivatives of Esters of Carboxylic Acids via Organometallic (Si, Ge, Sn) Reagents (1997)

Zaitseva, Galina S. ; Livantsova, Ljudmila I. ; Nasim, Mohammed ; [et al.]

Weinheim : Wiley-Blackwell

Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 739-746

add to mindlist on the mindlist

Details

ISSN: 0009-2940

Keywords: Germatranes ; Organotrihalogenogermanes ; Organometallic (Si, Ge, Sn) reagents ; Transmetallation ; Chemistry ; Inorganic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Trialkylstannyl esters of tris(2-hydroxyalkyl)amines, N(CH2CHROSnAlk3)3 (9-11 (R = H, Me; Alk = Et, Bu), react with X3GeC(R1)(R2)COOR3 (12-17) (X = Cl or Br; R1, R2=H, Me, Ph, SiMe3, COOEt; R3=Me, Et) to give esters of α-germatranylcarboxylic acids, N(CH2CHRO)3GeC(R1)(R2)-COOR3 (1-8), in high yields. The synthesis of esters 12-17 is reported. Esters of α-germatranyldiphenylacetic acid 24 and 25 can be obtained by treatment of diphenylketene with Et3SnOMe to give in situ Et3SnC(Ph2)COOMe (23), followed by reaction with GeCl4 to give in situ Cl3GeC(Ph2)COOMe (22 and further reactions with 9 or 11, respectively. Reduction of germatrane 6 with LiAlH4 in diethyl ether leads to cleavage of the germanium-carbon bond with subsequent formation of (2-hydroxyethyl)trimethylsilane. The crystal structures of 3, 6 and 7 are reported. 1-Acyloxygermatranes 26 and 27 are obtained by treatment of 1-methoxygermatrane (28) with diphenyl- and dichloroacetic acid, respectively.

Additional Material: 4 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/cber.19971300611

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

5

Electronic Resource

Synthesis, characterization, and structures of 1-(9-Fluorenyl)-germatrane and 1-(Phenylacetylenyl)germatrane (1997)

Zaitseva, Galina S. ; Karlov, Sergei S. ; Churakov, Andrei V. ; [et al.]

Weinheim : Wiley-Blackwell

Zeitschrift für anorganische Chemie 623 (1997), S. 1144-1150

add to mindlist on the mindlist

Details

ISSN: 0044-2313

Keywords: Trihalogenogermane ; Germatrane ; Transmetalation ; Crystal structure ; Chemistry ; Inorganic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Description / Table of Contents: Darstellung, Charakterisierung und Strukturen von 1-(9-Fluorenyl)germatran and 1-(Phenylacetylenyl)germatranÜber die Synthesen der Titelverbindungen, nämlich N(CH2CH2O)3GeY (2 Y=Fluorenyl; 4 Y=PhC≡C) durch Reaktion von X3GeY (1 Y=Fluorenyl, X=Br; 5 Y=PhC≡C, X=Cl) mit N(CH2CH2OSnR3)3 (3 R=Et; 6 R=Bu) wird berichtet und die Darstellung der neuen Verbindung 1 wird beschrieben. Die Strukturen der Verbindungen wurden durch Elementaranalysen sowie mittels 1H and 13C NMR-Spektroskopie bestimmt, 2 und 4 massenspektrometrisch charakterisiert. 1, 2 und 4 wurden mit Röntgenbeugungsmethoden analysiert.

Notes: Syntheses of the title compounds, viz. N(CH2CH2O)3GeY (2 Y=Fluorenyl; 4 Y=PhC≡C) by the reaction of X3GeY (1 Y=Fluorenyl, X=Br; 5 Y=PhC≡C, X=Cl) with N(CH2CH2OSnR3)3 (3 R=Et; 6 R=Bu) are reported including the preparation of the new compound 1. Identity and structures were established by elemental analyses, 1H and 13C NMR spectroscopy. 2 and 4 were characterized by mass spectrometry. Single crystal structures of 1, 2 and 4 were determined by X-ray diffraction methods.

Additional Material: 3 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/zaac.19976230723

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

6

Unknown

Thermodynamics and structure of molecular clusters in supercritical water (2000)

Kalinichev, A. ; Churakov, S.

In: 14th Symposium on Thermophysical Properties (Boulder 2000)

add to mindlist on the mindlist

Details

Publication Date: 2020-02-12

Keywords: 550 - Earth sciences

Type: info:eu-repo/semantics/conferenceObject

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

PAPER (OA)

S·F·X

Overview

7

Unknown

Thermodynamic of fluid mixtures at high temperature and pressures (2001)

Churakov, S. ; Gottschalk, M.

In: European Union of Geosciences (EUG) XI (Strasbourg 2001)

add to mindlist on the mindlist

Details

Publication Date: 2020-02-12

Keywords: 550 - Earth sciences

Type: info:eu-repo/semantics/conferenceObject

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

PAPER (OA)

S·F·X

Overview

8

Unknown

Ab-initio calculations of the proton location in topaz-OH, Al2SiO4(OH)2 (2004)

Churakov, S. ; Wunder, B.

In: Physics and Chemistry of Minerals

add to mindlist on the mindlist

Details

Publication Date: 2020-02-12

Description: The position of hydrogen in the structure of topaz-OH was determined by means of ab-initio quantum-mechanic calculations. Static lattice energy calculations predict the existence of four non-equivalent positions of protons, which are characterized by O4–H1... O1, O4–H2... O2, O4–H3... O3 and O4–H4... O4 hydrogen bonds. The distribution of the protons between positions of local equilibrium is controlled by the proton–proton avoidance rule and the strength of the hydrogen bonds. The most favourable configuration of hydrogen atoms is achieved for adjacent protons, which form O4–H3... O3 and O4–H4... O4 hydrogen bonds, respectively. The thermal excitation of atoms at a temperature of 55 K is large enough for the hydrogen atoms occasionally to change their positions to form O4–H1... O1 and O4–H2... O2 bonds. At ambient pressures and higher temperatures the protons are in a dynamic exchange between the allowed positions of local minima. As a consequence, for nearly room-temperature conditions, the dynamic change between different structural configurations leads to the violation of all possible symmetry elements and with that to space group #E5/E5#1. The flipping of the protons between different sites is achieved by simple rotation of the OH-dipole and does not produce any significant distortion of the framework of topaz, whose symmetry remains that of the space group Pbnm. Therefore, no reduction of symmetry has been observed in former X-ray studies on topaz-OH. Calculated IR absorption spectra of topaz-OH were found to be in good agreement with measured spectra. According to the calculations, the two favourable configurations of protons might correspond to the measured peak splitting within the OH-stretching range. An experimentally observed low-frequency band at 3520 cm–1 was assigned to the OH-stretching of the O4–H3... O3 bond, while the band at 3600 cm–1 was attributed to OH-stretching of the O4–H4... O4 hydrogen bond. The broad peak in FAR-IR frequency range at 100–150 cm–1 is attributed to the stretching of H3... O3 and H4... O4 contacts. The rate of proton exchange at 670 K among different sites was estimated by ab-inito molecular dynamic simulations. The calculations predict that flipping of adjacent protons between O4–H3... O3 and O4–H4... O4 bonds at 670 K occur at a rate of about 1.96 THz.

Keywords: 550 - Earth sciences

Type: info:eu-repo/semantics/article

Permalink