Synthesis of tricarbonyl η₆- and η₅- [(3-thiophenyl)organo]chromium and -manganese complexes

The syntheses of tricarbonyl η⁶-[(3-thiophenyl)arene] chromium 1a, 1b and η⁵-[(3-thiophenyl)cyclohexadienyl] manganese complexes 2 are reported using a Stille cross-coupling methodology. A two-step strategy involving a Stille reaction-exo-hydride abstraction sequence allowed selective access to cationic tricarbonyl η⁶-[(3-thiophenyl)arene]manganese complex 3. ¹ H-NMR data of these 3-thiophenylchromium and manganese complexes are presented as well as a comparison with the corresponding 2-thiophenyl- substituted derivatives described in the literature. The crystal structure determinations of 3-thiophenyl and 2-thiophenyl-η ⁶-(arene)Cr(CO)₃ complexes showing the conformations of the Cr(CO)₃ tripods are also reported.