[Tc<sup>I</sup>(NO)X(Cp)(PPh<sub>3</sub>)] Complexes (X<sup>–</sup> = I<sup>–</sup>, I<sub>3</sub><sup>–</sup>, SCN<sup>–</sup>, CF<sub>3</sub>SO<sub>3</sub><sup>–</sup>, or CF<sub>3</sub>COO<sup>–</sup>) and Their Reactions
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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.
