Stable Divalent Triarylstannates R<sub>3</sub>SnLi Derived from 2‑[(Dimethylamino)methyl]phenyllithium and SnCl<sub>2</sub> or R<sub>2</sub>Sn

The triarylstannate lithium compound [{κ<sup>1</sup>-<i>C</i>-(2-Me<sub>2</sub>NCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>}­{κ<sup>2</sup>-<i>C, N</i>-(2-Me<sub>2</sub>NCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>)}­SnLi­(THF)<sub>2</sub>] (<b>3a</b>) was obtained in 63% yield from the reaction of 2-Me<sub>2</sub>NCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>Li (<b>1</b>) with SnCl<sub>2</sub> in THF. Quantitative formation of <b>3a</b> was also observed on reacting <b>1</b> with [κ<sup>2</sup>-<i>C, N</i>-(2-Me<sub>2</sub>NCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>Sn] (<b>2</b>). Removal of one THF molecule occurred when <b>3a</b> was kept in vacuo; this process afforded [{κ<sup>1</sup>-<i>C</i>-(2-Me<sub>2</sub>NCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>)}­{κ<sup>2</sup>-<i>C, N</i>-(2-Me<sub>2</sub>NCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>}­SnLi­(THF)<sub>2</sub>] (<b>3b</b>). Also, THF-free (2-Me<sub>2</sub>NCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub>)<sub>3</sub>SnLi (<b>3c</b>) is likewise accessible. In the solid state (X-ray) both <b>3a</b> and <b>3b</b> are monomeric; notable structural features are the Sn–Li distances (2.860(6) and 2.72(2) Å, respectively) and the distortion of the tetrahedral geometry at Sn in the direction of a trigonal pyramidal one. In <b>3a</b>, one of the 2-Me<sub>2</sub>NCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub> anions is C-bonded to Sn, while N-coordination occurs to Li; in <b>3b</b>, two of the three 2-Me<sub>2</sub>NCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub> anions are κ<sup>2</sup>-<i>C,N</i> bonded. <sup>1</sup>H, <sup>13</sup>C, <sup>119</sup>Sn, and <sup>7</sup>Li NMR spectroscopic studies of the species <b>3</b> in <i>toluene</i> showed that both <b>3a</b> and <b>3b</b> are monomeric in solution; at temperatures below 253 K, via both the <sup>119</sup>Sn and <sup>7</sup>Li NMR spectra (toluene-<i>d</i><sub>8</sub>), the <sup>119</sup>Sn–<sup>7</sup>Li coupling (289 Hz) is nicely resolved. The exchange of aryl groupings (vide infra) as well as between coordinated and free-NMe<sub>2</sub> substituents remains fast on the NMR time scale at 183 K. 2D <sup>1</sup>H–<sup>1</sup>H EXSY spectroscopy confirmed that the 2-Me<sub>2</sub>NCH<sub>2</sub>C<sub>6</sub>H<sub>4</sub> groups present in stannate <b>3b</b> and bisaryltin­(II) <b>2</b> undergo chemical exchange. The 2D <sup>7</sup>Li–<sup>7</sup>Li EXSY spectrum points to the occurrence of chemical exchange of the lithium atoms of stannate <b>3b</b> and aryllithium <b>1</b>.