Etude théorique des complexes mono et dinucléaires du ruthénium à liaisons (sigma)-silane

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Rationalization of the Solvation Effects on the AtO+ Ground-State Change

International audience211At radionuclide is of considerable interest as a radiotherapeutic agent for targeted alpha therapy in nuclear medicine, but major obstacles remain because the basic chemistry of astatine (At) is not well understood. The AtO+ cationic form might be currently used for 211At-labeling protocols in aqueous solution and has proved to readily react with inorganic/organic ligands. But AtO+ reactivity must be hindered at first glance by spin restriction quantum rules: the ground state of the free cation has a dominant triplet character. Investigating AtO+ clustered with an increasing number of water molecules and using various flavors of relativistic quantum methods, we found that AtO+ adopts in solution a Kramers restricted closed-shell configuration resembling a scalar-relativistic singlet. The ground-state change was traced back to strong interactions, namely, attractive electrostatic interactions and charge transfer, with water molecules of the first solvation shell that lift up the degeneracy of the frontier π* molecular orbitals (MOs). This peculiarity brings an alternative explanation to the highly variable reproducibility reported for some astatine reactions: depending on the production protocols (with distillation in gas-phase or “wet chemistry” extraction), 211At may or may not readily react

Rationalization of the Solvation Effects on the AtO⁺ Ground-State Change

²¹¹At radionuclide is of considerable interest as a radiotherapeutic agent for targeted alpha therapy in nuclear medicine, but major obstacles remain because the basic chemistry of astatine (At) is not well understood. The AtO⁺ cationic form might be currently used for ²¹¹At-labeling protocols in aqueous solution and has proved to readily react with inorganic/organic ligands. But AtO⁺ reactivity must be hindered at first glance by spin restriction quantum rules: the ground state of the free cation has a dominant triplet character. Investigating AtO⁺ clustered with an increasing number of water molecules and using various flavors of relativistic quantum methods, we found that AtO⁺ adopts in solution a Kramers restricted closed-shell configuration resembling a scalar-relativistic singlet. The ground-state change was traced back to strong interactions, namely, attractive electrostatic interactions and charge transfer, with water molecules of the first solvation shell that lift up the degeneracy of the frontier π* molecular orbitals (MOs). This peculiarity brings an alternative explanation to the highly variable reproducibility reported for some astatine reactions: depending on the production protocols (with distillation in gas-phase or “wet chemistry” extraction), ²¹¹At may or may not readily react

Exploration of the metallic character of astatine

International audienc

211 At-labeled agents for alpha-immunotherapy: On the in vivo stability of astatine-agent bonds

International audienceThe application of 211 At to targeted cancer therapy is currently hindered by the rapid deastatination that occurs in vivo. As the deastatination mechanism is unknown, we tackled this issue from the viewpoint of the intrinsic properties of At-involving chemical bonds. An apparent correlation has been evidenced between in vivo stability of 211 At-labeled compounds and the AtÀR (R ¼ C, B) bond enthalpies obtained from relativistic quantum mechanical calculations. Furthermore, we highlight important differences in the nature of the AtÀC and AtÀB bonds of interest, e.g. the opposite signs of the effective astatine charges, which implies different stabilities with respect to the biological medium. Beyond their practical use for rationalizing the labeling protocols used for 211 At, the proposed computational approach can readily be used to investigate bioactive molecules labeled with other heavy radionuclides

Investigation of Astatine chemistry in solution

International audienc