[TcI(NO)X(Cp)(PPh3)] Complexes (X– = I–, I3–, SCN–, CF3SO3–, or CF3COO–) and Their Reactions

Reactions of [Tc(NO)Cl(Cp)(PPh3)] with a series of monodentate ligands X– (X– = I–, I3–, F3CSO3–, CF3COO–, or SCN–) result in a ready replacement of the chlorido ligand and the formation of complexes of the general composition [Tc(NO)X(Cp)(PPh3)]. Technetium retains its oxidation state “+1” and its pseudotetrahedral coordination environment. [Tc(NO)(SCN)(Cp)(PPh3)] is the first technetium complex with an S-coordinated SCN– ligand. The complexes are stable as solids. In solution, however, a slow isomerization of the thiocyanato compound into the thermodynamically more stable isothiocyanato species is observed, while solutions of [Tc(NO)(I3)(Cp)(PPh3)] undergo an internal oxidation under formation of the technetium(II) complex [Tc(NO)(I)2(Cp)]. All products were characterized by elemental analysis, NMR and IR spectroscopy, and X-ray structure analysis. Particularly, 99Tc NMR spectroscopy proved to be a valuable method for these types of technetium(I) compounds.