Abstract Phosphaalkynes 1 react regiospecifically in the presence of the thiotantalum (V) compound 2 to afford the 1, 2, 4-thiadiphospholes 3. These compounds can function both as η 1 and as η 5 ligands in complexes with group-6 metals.[4+ 2] Cycloaddition reactions only occur with phosphaalkynes or highly reactive acetylenes as reaction partners. These reactions afford on the one hand the functionalized 1, 2-thiaphospholes 17 and, on the ...
