Stepwise and Self-Assembly Synthesis of Tetranuclear Iron-Thiolate-Diisocyanide Metallocyclophane Complexes

Abstract

Treatment of known complex [Cp2Fe2 (μ‐SEt)2(CH3CN)2](BF4 )2 (1(BF4 )2) with 2 equiv of 1,4‐bis(isocyanomethyl)benzene (1,4‐CNCH2C6H4CH2NC; L1 ) or 4,4′‐diisocyanophenyl ether (4,4′‐CNC6H4OC6H4NC; L2 ) result in the formation of two new‐type diisocyanide complexes [Cp2Fe2 (μ‐SEt)2(1,4‐CNCH2C6H4CH2NC)2](BF4 )2 (2a(BF4 )2) or [Cp2Fe2 (μ‐SEt)2(4,4′‐CNC6H4OC6H4NC)2](BF4 )2 (2b(BF4 )2), respectively. The new‐type 24‐membered ring tetranuclear iron–thiolate–aryldiisocyanide metallocyclophane complex [Cp4Fe4 (μ‐SEt)4(μ‐1,4‐CNCH2C6H4CH2NC)2](BF4 )4 (3a(BF4 )4) has been synthesized by using a self‐assembly reaction between equimolar amounts of 1(BF4 )2 and 1,4‐bis(isocyanomethyl)benzene or by a stepwise route involving mixing a 1:1 molar ratio of complexes 1(BF4 )2 and 2a(BF4 )2. A similar approach was used through the application of equal molar ratio of complexes 1(BF4 )2 and 2b(BF4 )2 to give a 30‐membered ring tetranuclear iron–thiolate–aryldiisocyanide metallocyclophane complex [Cp4Fe4 (μ‐SEt)4(4,4′‐CNC6H4OC6H4NC)2][BF4 ]4 (3b(BF4 )4). The spectroscopic and electrochemical properties of four iron–sulfur core complexes were determined.