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.