Technetium(I) Dicarbonyl Complexes with NN-Aromatic Diimines

Technetium(I) dicarbonyl complexes [ 99 Tc(NN) 2 (CO) 2 ]OTf (NN = 2,2′-bipyridine and 1,10-phenanthroline) were prepared for the first time by treatment of [ 99 Tc(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 1 H and 99 Tc NMR and IR spectroscopy and SCXRD. These complexes are robust and do not undergo further decarbonylation. The possibility of formation of monocarbonyl [ 99 Tc(NN) 2 (py)(CO)] + and carbonyl-free [Tc(NN) 3 ] + complexes by decarbonylation of [ 99 Tc(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.