Tetrakis trimethylsilyl tetrahedrane, Properties

Tetrakis(trimethylsilyl)tetrahedrane (12) is a colorless crystalline solid, mp 202°. Unlike tetra-7-butyltetrahedrane (5), wliich melts at 135° with isomerization to the 

As with the isomerization of tetra-t-butyltetrahedrane to tetra-/-butylcyclobuta-diene, the isomerization of 12 to 18, 19 and 20 likely begins with opening to a diradical (discussed below for the parent) 21 which isomerizes to a (hradical 22 the second diradical isomerizes to the cyclobutadiene 13, but unlike the case in the tetra-t-buty system, the cyclobutadiene is of higher energy than the tetrahedrane, and furthermore can drain away to the low-energy aUg ne 18. A control experiment showed that 19 and 20 do not arise from the cyclobutadiene 19 was suggested to 

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