A Seven-Membered Aluminum Sulfur Allenyl Heterocycle Arising from the Conversion of an Aluminacyclopropene with CS<sub>2</sub>

The reaction of an aluminacyclopropene LAl[η<sup>2</sup>-C<sub>2</sub>(SiMe<sub>3</sub>)<sub>2</sub>] (<b>1</b>, L = HC(CMeNAr)<sub>2</sub>, Ar = 2,6-<i>i</i>Pr<sub>2</sub>C<sub>6</sub>H<sub>3</sub>) with CS<sub>2</sub> in the temperature range from −78 °C to room temperature affords the first seven-membered aluminum sulfur-containing heterocyclic compound [LAl]<sub>2</sub>(μ-S)[η<sup>2</sup>-SC(SiMe<sub>3</sub>)CC(SiMe<sub>3</sub>)] (<b>2</b>) bearing an allenyl group. The structural characterization of <b>2 </b>and the analogous compound LAl[OC(O)C<sub>2</sub>(SiMe<sub>3</sub>)<sub>2</sub>] (<b>3</b>) of the proposed intermediate <b>A</b> and the variable-temperature <sup>1</sup>H NMR kinetic study of this reaction may give a better understanding on this unusual conversion.