Trieneiron tricarbonyl and bisallyldi-iron hexacarbonyl π-complexes from photolysis of divinylcyclopropanes induced by iron pentacarbonyl

The photolysis of trans-1-isopropenyl-4-methylenespiro[2.x]alkanes (1) (x = 4,5, or 6) in presence of Fe(CO)₅ at room temperature leads to formation (60%) of isomeric mononuclear irontricarbonyl π-complexes of linear trienes [(2) and (3)] and (10%) of a di-ironhexacarbonyl-bis-π-allyl complex of a branched triene (4).