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}] and Fe3(CO)10{H2CCC(H)C(O)C{CH2(O)CH3}CCH2}]

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 Fe2(CO)6{H2CCCCH2} is the main product of the reactions with BUD or DCB in all conditions. The complexes Fe2(CO)6{H2CCC(H)C(OMe)O} and Fe3(CO)10{H2CCC(H)C(O)C{CH2(O)CH3}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{H2CCCCH2} 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 Fe3(CO)10{H2CCC(H)C(O)C{CH2(O)CH 3}CCH2} contains one Fe(CO)4 and one Fe2(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.