A seven-membered aluminum sulfur allenyl heterocycle arising from the conversion of an aluminacyclopropene with CS2

The reaction of an aluminacyclopropene LAleta2-C2(SiMe3)2] (1, L = HC(CMeNAr)2, Ar = 2,6-iPr2C6H3) with CS2 in the temperature range from -78 degrees C to room temperature affords the first seven-membered aluminum sulfur-containing heterocyclic compound LAl]2(mu-S)eta2-SC(SiMe3)=C=C(SiMe3)] (2) bearing an allenyl group. The structural characterization of 2 and the analogous compound LAlOC(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.