Novel C–C and C–N coupling reactions on a di-iron–α-di-imine complex in the reaction of Fe 2 (CO) 6 {RNC(H)C(H)NR} with methyl propynoate; X-ray crystal structures of Fe 2 (CO) 5 {(c-C 6 H 11 )NCHCHN(c-C 6 H 11 )C(O)CHCCO 2 Me}, Fe 2 (CO) 6 {Pr i NCHCHN(Pr i )CHCCO 2 Me} and Fe 2 (CO) 4 {Pr i NCHCHN(Pr i )CHCCO 2 Me}

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.