Dieneiron carbonyl complexes

A variety of synthetic routes to monoene and polyene tri-fluorophosphine-transition metal complexes have been devised. Direct photochemically induced reaction of a metal-PF3 complex with an activated alkene or diene (method A) has proved useful only for iron, the products being either [Fe(PF3)4(alkene)J or [Fe(PF3)3(diene)] (194). Mixed carbonyl-trifluorophosphine complexes of the type [Fe(PF3)x(CO)3 x(diene)] result from either thermal or photochemical reactions of dieneiron carbonyl complexes and PF3 (52, 53) (method B). The compounds are fluxional. 

Pentacarbonyliron releases its carbonyl ligands upon heating or exposure to UV light, and the resulting unsaturated species are known to react with various kinds of 1,3-dienes to form dieneiron tricarbonyl complexes. For example, (butadiene)tricar-bonyliron is prepared by the direct reaction of 1,3-butadiene with Fe(CO)5 at 130-140 °C in a closed system (eq (12)) [42]. 

Dieneiron carbonyl and arenechromium carbonyl complexes in which the chirality is introduced by metal coordination and depends upon the structure of the complex. In these systems, the organometallic complex is destroyed in the cleavage reaction. 

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