Donor–Acceptor Stabilized Tetra(silanimine)

The synthesis of an oligo­(silanimine) is described. The reaction of the amidinato silylene [LSiN­(SiMe<sub>3</sub>)<sub>2</sub>] (<b>1</b>, L = PhC­(N<i>t</i>Bu)<sub>2</sub>) with SiI<sub>4</sub> in toluene afforded a mixture of the silanimine [LSi­(I)­NSiI<sub>3</sub>] (<b>2</b>), SiMe<sub>3</sub>I, and Si<sub>2</sub>I<sub>6</sub>. The mechanistic studies showed that <b>1</b> reacts with SiI<sub>4</sub> to form the silyl ionic intermediate “{LSi­(I)­N­(SiMe<sub>3</sub>)<sub>2</sub>}<sup>+</sup>{SiI<sub>3</sub>}<sup>−</sup>”, which then eliminates SiMe<sub>3</sub>I and “SiI<sub>2</sub>” to form the silanimine intermediate “LSi­(I)­NSiMe<sub>3</sub>”. It further undergoes a substitution with another molecule of SiI<sub>4</sub> to form a mixture of <b>2</b> and SiMe<sub>3</sub>I. In addition, “SiI<sub>2</sub>” undergoes an oxidative addition with SiI<sub>4</sub> to form Si<sub>2</sub>I<sub>6</sub>. Subsequently, compound <b>2</b> reacted with [LiN­(SiMe<sub>3</sub>)­Ar] to form the silanimine [LSi­(I)­NSiI<sub>2</sub>N­(SiMe<sub>3</sub>)­Ar] (<b>6</b>, Ar = 2,6-<i>i</i>Pr<sub>2</sub>C<sub>6</sub>H<sub>3</sub>), which was then treated with KC<sub>8</sub> to give the donor–acceptor stabilized tetra­(silanimine) [LSiN­(SiMe<sub>3</sub>)­SiNAr]<sub>2</sub> (<b>7</b>). It comprises four formal silanimine “>SiN-” units, which are linked together. Compounds <b>2</b>, <b>6</b>, and <b>7</b> were characterized by NMR spectroscopy and X-ray crystallography.