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  • 1
    Electronic Resource
    Electronic Resource
    Kleine Ringe, 78. Tri-tert-butyl(trimethylsilyl)cyclobutadien und Tri-tert-butyl(trimethylsilyl)tetrahedran (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 173-189 
    Details
    ISSN: 0009-2940
    Keywords: Diazo compounds ; Transition-metal complexes ; Photoisomerization ; Homocyclopropenylium ions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Small Rings, 78[1]. - Tri-tert-butyl(trimethylsilyl)cyclobutadiene and Tri-tert-butyl(trimethylsilyl)tetrahedraneThe chemistry of diazo(1,2,3-tri-tert-butylcyclopropenyl)(trimethylsilyl)methane (6) is unexpectedly diverse. Upon irradiation it fragments exclusively into the acetylenes 7 and 8. Flash thermolysis, on the other hand, gives  -  aside from the two acetylenes  -  tri-tert-butylazete (10) and trimethylsilyl cyanide (11). Upon heating 6 presumably isomerizes via betaine 17 to Dewar-diazabenzene 13  -  which is split into 10 and 11  -  and diazabenzvalene 18. This reaction course is supported by the isolation of the carbonyliron complexes 15 and 16,  -  The CuCl-catalyzed thermal decomposition again follows a different route. Under these conditions tri-tert-butyl(trimethylsilyl)cyclobutadiene (5) is formed, probably as a weak CuCl complex. Only after addition of ethylenebis(diphenylphosphane) free cyclobutadiene 5 can be isolated. Upon irradiation of 5 a quantitative isomerization to tri-tert-butyl(trimethylsilyl)tetrahedrane (29) occurs. This second, spectroscopically unequivocally confirmed tetrahedrane melts at 179°C. In solution the isomerization to cyclobutadiene 5 starts at about 160°C. That means, it is thermally even more stable than tetra-tert-butyltetrahedrane.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270126
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  • 2
    Electronic Resource
    Electronic Resource
    Kleine Ringe, 79. Synthese und Eigenschaften neuer Silyl-substituierter Cyclobutadiene und Tetrahedrane (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 191-200 
    Details
    ISSN: 0009-2940
    Keywords: Diazo compounds ; Valence isomerization ; „Corset effect“ ; limits of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Small Rings, 79[1].  -  Synthesis and Properties of Novel Silyl-Substituted Cyclobutadienes and TetrahedranesThe cyclobutadienes 2b, d as well as the corresponding tetrahedranes 3b, d have been prepared according to the “Masamune route” by starting from the diazo compounds 1b, d. Low-temperature 13C—NMR measurements of the cyclobutadienes 2a, b, d lead to the first exact values of the barrier heights in the interconversion of the two rectangular forms of the cyclobutadienes. Fluorodesilylation of 3d probably proceeds via tri-tert-butyltetrahedrane (3h) and cyclobutadiene 2h and finally yields diketone 18. Reaction of tetrahedrane 3d with LiAlH4 in boiling THF leads to tetrahedrane 3e, which is much less stable than all previously known tetrahedrane derivatives.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270127
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  • 3
    Electronic Resource
    Electronic Resource
    Tri-tert-butyl(trimethylgermyl)cyclobutadien und Tri-tert-butyl(trimethylgermyl)tetrahedran (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 201-204 
    Details
    ISSN: 0009-2940
    Keywords: Diazo compounds ; Homologation ; Valence isomerization ; Germanium compounds ; Tetrahedranes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Small Rings, 80[1].  -  Tri-tert-butyl(trimethylgermyl)cyclobutadiene and Tri-tert-butyl(trimethylgermyl)tetrahedraneIn the course of our research on silyl-substituted diazo compounds as precursors of cyclobutadienes and tetrahedranes the synthesis of the title compounds 16 and 17 has also been accomplished. Their properties are comparable to those of the silyl-substituted homologous compounds. Tri-tert-butyl(trimethylgermyl)tetrahedrane (17) melts without decomposition at 143°C and thus proves to be as stable as tri-tert-butyl(trimethylsilyl)tetrahedrane. The interconversion of the rectangular forms of tri-tert-butyl(trimethylgermyl)cyclobutadiene (16) proceeds with an activation energy below 4 kcal/mol, which is nearly the same as of tri-tert-butyl(trimethylsilyl)cyclobutadiene.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270128
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