An organometallic mercaptopyridine complex with unusual bond shift fluxionality: Metal-mediated tautomerism of (pentamethylcyclopentadienyl)bis(pyridine-2-thiolato)rhodium(III)

Studies have been carried out on unique molecular non-rigidity of Cp*Rh¹¹¹(PyS)₂ (PyS = pyridine-2-thiolato). One PyS ligand bonds to the rhodium ion in an S-monodentate mode (Rh-S(2) = 2.3799(9) Å) while the other ligand chelates to the metal in an N,S-bidentate mode (Rh-S(1) = 2.4380(9); Rh-N(1)= 2.089(2) Å). Both PyS ligands possess a significant contribution from the thiol tautomer in the solid state. Even though the conformation and configuration of the molecule are still retained in solution, an unusual metal-mediated tautomeric non-rigidity for the PyS region is observed in the solution around room temperature. (C) 2000 Elsevier Science S.A.