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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