Novel C–C and C–N coupling reactions on a di-iron–α-di-imine complex in the reaction of Fe2(CO)6{RNC(H)C(H)NR} with methyl propynoate; X-ray crystal structures of Fe2(CO)5{(c-C6H11)NCHCHN(c-C6H11)C(O)CHCCO2Me}, Fe2(CO)6{PriNCHCHN(Pri)CHCCO2Me} and Fe2(CO)4{PriNCHCHN(Pri)CHCCO2Me}

Abstract

The reaction of Fe₂(CO)₆(Rdab)=[Rdab = RNCHCHNR; R = Prⁱ or c-C₆H₁₁(cyclohexyl)] with methyl propynoate at room temperature yields two products (X-ray): Fe₂(CO)₅{RNCHCHN(R)C(O)CHCCO₂Me}, where the Rdab ligand, a CO, and an alkyne are coupled to form an 8e donating ligand, and Fe₂(CO)₆{RNCHCHN(R)CHCCO₂Me}, containing a 6e donating heterocyclic ligand, formed by coupling of the terminal alkyne C atom to both the Rdab N atoms in an unusual fashion; heating of the latter complex yields Fe₂(CO)₄{RNCHCHN(R)CHCCO₂Me}(X-ray), with an unprecedented bis-η³-aza-allyl bonded ligand.