2,5‐Dimethylthiophene coordination to three metal centers in the complexes (η4, S‐μ3‐2,5‐Me2T)(IrCp*) [M(CO)2Cp]2 where MMo or W

The 2,5-dimethylthiophene (2,5-Me2T) ligand in the isomers Cp*Ir(η4-2,5-Me2T) (1) and Cp*Ir(C,S-2,5-Me2T) (2) is activated to react with the dimers Cp(CO)2MM(CO)2Cp[MMo (3), W (4)] to give complexes (5,6) in which the thiophene is coordinated to three metals. Oxidation of 5 with Cp2Fe+ removes the Mo dimer to give Cp*Ir(η5-2,5-Me2T)2+. Reaction of 5 with CO displaces the Mo as [CpMo(CO)3]2 to give Cp*Ir(CO)(C,S-2,5-Me2T) (7). Ultraviolet photolysis of 1 provides a convenient route to the ring-opened isomer 2. Despite the remarkable nature of the thiophene coordination in 5 and 6, its reactivity does not suggest new pathways that would lead to the hydrodesulfurization of thiophenes.

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