Technetium(I) carbonyl complexes for nuclear medicine: Coordination-chemical aspect

• Published in: Coordination chemistry reviews 2023-02, Vol.476, p.214911, Article 214911
• Main Authors: Sidorenko, Georgy V., Miroslavov, Alexander E., Tyupina, Margarita Yu
• Format: Article
• Language: English
• Subjects: fac-Tc(CO)3+ core; Isomerism; Labeling strategies; Metal-mediated ligand transformations; Tc bioconjugates; Technetium(I) carbonyl complexes
• ISSN: 0010-8545; 1873-3840
• DOI: 10.1016/j.ccr.2022.214911

•Coordination trends.•Isomerism.•Metal-mediated reactions.•Synthesis routes.•Chelators. Studies concerning the development of radiopharmaceuticals based on the Tc(I) carbonyl core are considered from the coordination-chemical viewpoint. The coordination behavior of the fac-Tc(CO)3+ core (hard/soft acid properties, complexation kinetics and thermodynamics, coordination preferences, mutual influence of ligands) is discussed in detail. Particular attention is paid to possible coordination isomerism and stereoisomerism of the complexes—problems that often escape from researchers’ attention. Metal-mediated ligand transformations, which can play both positive and negative role in the synthesis, are summarized for the first time. A comparative analysis of possible labeling strategies (one-pot, prelabeling, postlabeling) is made with more detailed consideration of the click-to-chelate and chelate-then-click approaches. A summary of ligands and ligand systems used for tethering the fac-Tc(CO)3+ core to biomolecules is made, including typical complexation conditions, yields, and key characteristics of the bioconjugate stability. Alternative technetium carbonyl coordination cores (higher carbonyls, mer-Tc(CO)3+, Tc(CO)2(NO)2+, Tc(CO)2(phosphine, isonitrile)2+, Tc(CO)2(isonitrile)4+) are briefly discussed. Coordination-chemical problems deserving, in authors’ opinion, a more detailed study are pointed out.