Coordination Chemistry of Technetium and Rhenium Complexes

The coordination chemistry of technetium and rhenium encompasses a rich array of oxidation states, ligand environments and applications that bridge fundamental inorganic chemistry and nuclear medicine. Both elements occupy Group 7 of the periodic table and share many electronic and structural properties, yet differ markedly in their radioisotopic behaviour. Technetium-99m, with its favourable half-life and γ-emission, is the workhorse of single-photon emission computed tomography, while non-radioactive rhenium analogues serve as chemical models and therapeutic radionuclides. Core motifs include fac-[M(CO)₃]+ tricarbonyl fragments, cyclopentadienyl and arene sandwich architectures, nitrosyl adducts and isocyanide complexes. These frameworks offer fine control over redox potentials, kinetic inertness and donor–acceptor interactions, enabling tailored radiopharmaceutical design and catalysis. Advances in spectroscopic methods—such as ⁹⁹Tc NMR and X-ray absorption—combined with density functional theory have illuminated subtle electronic effects across oxidation states from +VII to –I. The interplay of ligand substitution, steric tuning and electronic modulation underpins the creation of stable complexes that resist in vivo degradation, facilitate targeted delivery and extend the reach of molecular imaging and therapy. Globally, this field continues to yield versatile platforms for diagnostic and therapeutic applications, while deepening our understanding of late-transition-metal bonding and reactivity.

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Coordination Chemistry of Technetium and Rhenium Complexes publication trend

The graph below shows the total number of articles in coordination chemistry of technetium and rhenium complexes across all publications each year (not limited to Nature Index journals).

Technical terms

Coordination complex: A metal centre bound to surrounding molecules or ions (ligands) via coordinate covalent bonds.

Ligand: An atom, ion or molecule that donates one or more electron pairs to a metal centre in a coordination complex.

Oxidation state: The formal charge assigned to a metal centre reflecting electron loss or gain relative to the neutral atom.

Cyclopentadienyl ligand: A five-membered aromatic ring (Cp) that binds metals in an η⁵-fashion, forming stable metallocenes or half-sandwich complexes.

Bis-arene sandwich complex: An organometallic species in which a metal ion is sandwiched between two aromatic rings, each bound in an η⁶-mode.

Density functional theory (DFT): A quantum mechanical modelling method used to investigate the electronic structure and properties of molecules and materials.

Radiopharmaceutical: A coordination complex containing a radionuclide, used for diagnostic imaging or targeted radiotherapy in medicine.

References

1. [Tc(NO)(Cp)(PPh3)Cl] and [Tc(NO)(Cp)(PPh3)(NCCH3)](PF6), and Their Reactions with Pyridine and Chalcogen Donors. Molecules (2024).
2. Na[Tc(CO)(CN p -F-Ar DArF2 ) 4 ]: an isocyanide analogue of the elusive Na[Tc(CO) 5 ]. Chemical Communications (2023).
3. Naphthalene Exchange in [Re(η6‐napht)2]+ with Pharmaceuticals Leads to Highly Functionalized Sandwich Complexes [M(η6‐pharm)2]+ (M=Re/99mTc). Chemistry - A European Journal (2021).