Technetium(I) Dicarbonyl Complexes with NN-Aromatic Diimines

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Radiochemistry

Background:

• Technetium complexes are crucial in nuclear medicine.
• The synthesis and characterization of novel technetium carbonyl complexes are of significant interest.
• Understanding the stability and reactivity of technetium carbonyls informs the development of new radiopharmaceuticals.

Purpose of the Study:

• To synthesize and characterize novel technetium(I) dicarbonyl complexes with 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen).
• To investigate the stability and decarbonylation potential of these newly synthesized technetium complexes.
• To computationally analyze the thermodynamic feasibility of forming monocarbonyl and carbonyl-free technetium complexes.

Main Methods:

• Synthesis of technetium(I) dicarbonyl complexes [⁹⁹Tc(NN)₂(CO)₂]OTf (NN = bpy, phen) from [⁹⁹Tc(OTf)(CO)₅].
• Characterization using ¹H and ⁹⁹Tc NMR, IR spectroscopy, and single-crystal X-ray diffraction (SCXRD).
• Density Functional Theory (DFT) calculations to assess the thermodynamics of decarbonylation.

Main Results:

• Successfully synthesized and isolated red crystalline technetium(I) dicarbonyl complexes.
• Confirmed the structure and purity of the complexes through spectroscopic and SCXRD analyses.
• DFT calculations indicated that further decarbonylation to monocarbonyl or carbonyl-free complexes is thermodynamically unfavorable at room and elevated temperatures.

Conclusions:

• The synthesized technetium(I) dicarbonyl complexes are robust and resistant to decarbonylation.
• The study provides fundamental insights into the stability of technetium carbonyl complexes.
• Findings suggest that these dicarbonyl complexes are stable intermediates for potential applications in radiochemistry.