An interesting fact to observe is that Collman's reagent causes umpolang at the carbonyl centre. Thus, a carbonyl compound may be generated by treating alkyl-iron complex with an electrophile (Scheme 5).

Scheme 5

Examples:

Ref: J. Y. Merour, J. L. Roustan, C. Charrier, J. Benaim, J. Collin, P. Cadiot, J. Organomet. Chem. 1979 , 168 , 337.

Ref : J. E. McMurry, A. Andrejs, G. M. Ksander, J. H. Musser, M. A. Johnson, Tetrahedron 1981 , 37 , 319.

 

3.6.4.4 Hydrogenation of Alkyne

Iron phosphine catalysts, known as Bianchini catalysts, are known for selective hydrogenation of terminal alkynes to give alkenes (Scheme 6). The selectivity is explained by the reluctance of iron hydride complex to insert alkenes. The mechanism is depicted below in Scheme 7.

Scheme 6