Cyclooctatetraene complexes molybdenum

This quadruply bonded complex containing a bridging cyclooctatetraene is prepared in 20% yield. The molybdenum analogue can be prepared by a similar procedure in 35% yield d. 

A number of metal complexes catalyses specific alkyne polymerizations, giving rise to four-, six- or eight-membered carbocyclic rings. The first work in this area was the nickel-catalysed formation of cyclooctatetraene (40) from acetylene by the group of Reppe ", but since then formation of cyclic systems from acetylenes has been found to be also catalysed by molybdenum, cobalt, iridium and tantalum. ... 

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