Reaction of Fe₃(CO)₁₂ with but-2-yn-1,4-diol, 1,4-dichloro-but-2-yne, propargyl-alcohol and propargyl-chloride. the X-ray structures of [Fe₂(CO)₆{H₂CCCCH₂}], [Fe₂(CO)₆{H₂CCC(H)C(OCH₃)O}]

The reactions of Fe₃(CO)₁₂ with but-2-yn-1,4-diol (BUD), 1,4-dichloro-but-2-yne (DCB), propargyl alcohol (PA) and propargyl chloride (PC) in KOH/CH₃OH solutions (followed by acidification with HCl) and under thermal conditions have been examined. The complex Fe ₂(CO)₆{H₂CCCCH₂} is the main product of the reactions with BUD or DCB in all conditions. The complexes Fe ₂(CO)₆{H₂CCC(H)C(OMe)O} and Fe ₃(CO)₁₀{H₂CCC(H)C(O)C{CH₂(O)CH ₃}CCH₂} are the main products obtained respectively in the reactions with propargyl chloride (PC) or propargyl alcohol (PA) in basic methanolic solution. The structures of the three complexes have been determined by means of X-ray analysis. Complex Fe₂(CO)₆{H ₂CCCCH₂} contains a butatrienyl ligand in an uncommon structural arrangement. The formation of complex Fe₂(CO) ₆{H₂CCC(H)C(OMe)O} requires CO and methanol activation; its ferrole like structure contains a coordinated acetate group. Complex Fe ₃(CO)₁₀{H₂CCC(H)C(O)C{CH₂(O)CH ₃}CCH₂} contains one Fe(CO)₄ and one Fe ₂(CO)₆ fragments linked through a carbon atom chain derived from the insertion of CO and dimerization of propargyl alcohol (with substitution of OCH₃ from methanol in the place of OH). Comments on the syntheses and on the reaction pathways leading to the complexes are made.