Novel μ-CO-Containing Butterfly Fe/S Cluster Anions Generated from Tetrathiols, Fe₃(CO)₁₂, and Et₃N: Their Reactions with Electrophiles To Give Neutral Butterfly Fe/S Cluster Complexes

Tetrathiol 1,2,4,5-(HSCH2)4C6H2 reacted with Fe3(CO)12 and Et3N followed by treatment of the intermediate μ-CO-containing tetraanion {[(μ-CO)Fe2(CO)6]4[1,2,4,5-(μ-SCH2)4C6H2]}4− (7) with 2-furancarbonyl chloride to give quadruple-butterfly complex [(μ-σ,π-C4H3O)Fe2(CO)6]4[1,2,4,5-(μ-SCH2)4C6H2] (9), whereas triple-butterfly complex [(μ-Ph2P)Fe2(CO)6]2[Fe2(CO)6][1,2,4,5-(μ-SCH2)4C6H2] (11) could be produced by reaction of Ph2PCl with the μ-CO-containing dianion {[(μ-CO)Fe2(CO)6]2[Fe2(CO)6][1,2,4,5-(μ-SCH2)4C6H2]}2− (10) generated in situ from the initially formed tetraanion 7. Similarly, the triple-butterfly complexes [(μ-Ph2P)Fe2(CO)6]2[Fe2(CO)6][(μ-SCH2)4C] (14) and [(μ-σ,π-CH2CHCH2)Fe2(CO)6]2[Fe2(CO)6][(μ-SCH2)4C] (16) were produced by reaction of Ph2PCl or CH2CHCH2Br with the μ-CO-containing dianion {[(μ-CO)Fe2(CO)6]2[Fe2(CO)6][(μ-SCH2)4C]}2− (13) formed in situ from tetraanion {[(μ-CO)Fe2(CO)6]4[(μ-SCH2)4C]}4− (12) generated initially by reaction of tetrathiol C(CH2SH)4 with Fe3(CO)12 and Et3N. The double-butterfly complex [Fe2(CO)6]2[(μ-SCH2)4C] (15) derived in situ from dianion 13 was also isolated as a minor product along with major products 14 and 15. All the new complexes 9, 11, and 14−16 were characterized by elemental analysis and IR and NMR spectroscopy, as well as by X-ray crystallography for 9, 11, 14, and 15.