An isolable radical anion and dianion of a cyclotetrasilane: Synthesis and structure of [Si{1,2-(NEt)(2)C6H4}](4)(-) and [Si{1,2-(NEt)(2)C6H4}](4)(2-)

Silicon squares up: The silylene Si[1,2-(NR)2C6H4] (R=CH2tBu) is thermally stable owing to its bulky substituent. What effect will a reduction of the size of R have on the stability of a two-coordinate SiII species? Results show that a silylene with R=Et cannot be isolated but will yield a stable radical anion (see picture) and dianion of a cyclotetrasilane.