Technetium(I) dicarbonyl complexes [99Tc(NN)2(CO)2]OTf (NN = 2,2′-bipyridine and 1,10-phenanthroline) were prepared for the first time by treatment of [99Tc(OTf)(CO)5] in a melt of the corresponding heterocycle. The dicarbonyl complexes were isolated in the form of red crystals and unambiguously characterized by 1H and 99Tc NMR and IR spectroscopy and SCXRD. These complexes are robust and do not undergo further decarbonylation. The possibility of formation of monocarbonyl [99Tc(NN)2(py)(CO)]+ and carbonyl-free [Tc(NN)3]+ complexes by decarbonylation of [99Tc(NN)2(CO)2]+ was analyzed with the aid of DFT calculations. It was shown that the formation of these complexes is thermodynamically unfavorable both at room and elevated temperatures.