Sulfur-containing stable five-membered “cycloallene” complexes: 1-thia-2-zircona- and 1-thia-2-titanacyclopenta-3,4-dienes

Abstract

Stable five-membered metallacyclic allenes that contain a sulfur atom were synthesized and structurally characterized. Low-valent zirconocene and titanocene reacted with alkynylthioamides to afford 1-thia-2-metallacyclopenta-3,4-diene compounds in moderate to excellent yields. The molecular structure of the zirconium complexes indicated their cycloallene structure, while an η²-alkyne-coordinated structure might be more responsible for the titanium complexes. Hydrolysis of the compounds gave the corresponding (Z)-alkenylthioamides predominantly. Deuterolysis resulted in >99% D incorporation.