The First Example of Macrocycles Containing Butterfly Transition Metal Cluster Cores via Novel Tandem Reactions

A novel type of double butterfly, two μ-CO-containing dianions {[(μ-CO)Fe₂(CO)₆]₂[μ-SCH₂(CH₂OCH₂)_nCH₂S-μ]}^2- (m₁, n = 2, 3), has been synthesized from dithiol HSCH₂(CH₂OCH₂)_nCH₂SH (n = 2, 3), Fe₃(CO)₁₂, and Et₃N in THF at room temperature. While dianions m₁ react in situ with CS₂ followed by treatment with dihalide 1,4-(BrCH₂)₂C₆H₄ or 1,4-I(CH₂)₄I to give macrocyclic clusters [μ-SCH₂(CH₂OCH₂)_nCH₂S-μ](μ-CS₂ZCS₂-μ)[Fe₂(CO)₆]₂ (1a, n = 2, Z = 1,4-(CH₂)₂C₆H₄; 1b, n = 3, Z = (CH₂)₄), reactions of dianions m₁ with (μ-S₂)Fe₂(CO)₆ followed by treatment with dihalide 1,4-I(CH₂)₄I afford macrocyclic clusters [μ-SCH₂(CH₂OCH₂)_nCH₂S-μ]{[Fe₂(CO)₆]₂(μ₄-S)}₂[μ-S(CH₂)₄S-μ] (2a, n = 2; 2b, n = 3). The crystal structures of 1a and 2b are described.