18169-72-7Relevant articles and documents
Small Rings, 78. - Tri-tert-butyl(trimethylsilyl)cyclobutadiene and Tri-tert-butyl(trimethylsilyl)tetrahedrane
Maier, Guenther,Born, Dieter,Bauer, Ines,Wolf, Reinhard,Boese, Roland,Cremer, Dieter
, p. 173 - 190 (2007/10/02)
The 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 presumbaly 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 deg C.In solution the isomerization to cyclobutadiene 5 starts at about 160 deg C.That means, it is thermally even more stable than tetra-tert-butyltetrahedrane. - Key Words: Diazo compounds / Transition-metal complexes / Photoisomerization / Homocyclopropenylium ions
