A Seven-Membered Aluminum Sulfur Allenyl Heterocycle Arising from the Conversion of an Aluminacyclopropene with CS2

The reaction of an aluminacyclopropene LAl[η2-C2(SiMe3)2] (1, L = HC(CMeNAr)2, Ar = 2,6-iPr2C6H3) with CS2 in the temperature range from −78 °C to room temperature affords the first seven-membered aluminum sulfur-containing heterocyclic compound [LAl]2(μ-S)[η2-SC(SiMe3)CC(SiMe3)] (2) bearing an allenyl group. The structural characterization of 2 and the analogous compound LAl[OC(O)C2(SiMe3)2] (3) of the proposed intermediate A and the variable-temperature 1H NMR kinetic study of this reaction may give a better understanding on this unusual conversion.