A convenient synthesis of the technetium complex [Tc(NO)Cl(Cp)(PPh3)] and some reactions of this novel precursor were successfully done. As a continuation of these promising results, the present thesis describes attempts concerning: i) a further investigation of the reactivity of [Tc(NO)Cl(Cp)(PPh3)] towards other monodentate ligands. ii) the synthesis of new organotechnetium precursors in the lower oxidation state “+I” of this element. iii) the extension of the former work to substituted derivatives of cyclopentadienyl, which in turn may open an access for coupling reactions with biologically active species. iv) the extension of our knowledge about the less-explored cyclopentadienyl chemistry of technetium.