The catalytic dimerisation of dienes by nitrosylcarbonyl transition-metal compounds

Butadiene and isoprene have been found to dimerise rapidly, under relatively mild conditions, by the catalytic action of dicarbonyldinitrosyliron and dicarbonyldinitrosyl(π-allyl)iron. Only norbornadiene is known to react in a similar manner, and the system appears unique in its indifference to additives. Sunlight, however, had a marked activating effect, decreasing the temperature required for high conversion of monomer from 100° to room temperature.