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. 1H-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-η6-(arene)Cr(CO)3 complexes showing the conformations of the Cr(CO)3 tripods are also reported.