METALOCYCLOPENTADIENE COMPLEXES OF IRIDIUM AND RHODIUM AND THEIR ROLE IN CATALYTIC CYCLOTRIMERIZATION OF DISUBSTITUTED ACETYLENES

Metalocyclopentadiene complexes of iridium (III) and rhodium(III) have been prepared from acetylenes. Provisional structures have been assigned to these metalocycles on the basis of infrared and nmr spectra of five- and six-coordinate complexes. Cyclotrimerization of disubstituted acetylenes is catalyzed by the coordinatively unsaturated metalocycles. Using an isotopically labeled substrate, the sequential cyclotrimerization of acetylenes has been elucidated. A tentative mechanism is proposed for acetylene cyclization. © 1968, American Chemical Society. All rights reserved.