Reaction of the Silylene PhC(N t Bu) 2 Si t Bu with 4,4′‐Bis(dimethylamino)thiobenzophenone and Treatment of the Silylene PhC(N t Bu) 2 SiC(SiMe 3 ) 3 with 3,5‐Di‐ tert ‐butyl‐ o ‐benzoquinone

The reaction of LSi t Bu [L = PhC(N t Bu) 2 ] ( 1 ) with 4,4′‐bis(dimethylamino)thiobenzophenone resulted in the [1+2]‐cycloaddition product silathiacyclopropane 3 , bearing a three‐membered SiCS ring. The reaction of LSiC(SiMe 3 ) 3 ( 2 ) with 3,5‐di‐ tert ‐butyl‐ o ‐benzoquinone leads to the [1+4]‐cycloaddition product 4 . In 3 the silicon atom is five‐ and in 4 it is four‐coordinate. Compounds 3 and 4 were characterized by spectroscopic and spectrometric techniques. The molecular structures of 1 , 3 , and 4 were unequivocally established by single‐crystal X‐ray structure analysis.