Verdazyl ligands have demonstrated viability in studying radical coordination complexes, as they

are redox-active and maintain this activity when coordinated to metal ions. They have also

shown strong magnetic exchange interactions between the radicals and the coordinated metal

ions. Together this has resulted in electronic structures that exhibit unusual properties such as

valence tautomerism (in which isomers differ in the distribution of electrons between the metal

and ligand) and redox induced spin-state switching. Actinides have the potential for novel

coordination chemistry because of their spatially extended 5f orbital, with actinide coordination

compounds offering many potentially exciting avenues for exploration, especially with radical

ligands. We are reporting on our ongoing work to design a polydentate verdazyl ligand for the

synthesis and characterization of actinide-radical complexes.

To test the coordination capacity of such a polydentate ligand with actinides, we are using a

polypyridine-hydrazone ligand. It was synthesized via a condensation reaction between

2,6-pyridinedicarboxaldehyde and hydrazinopyridine to coordinate to a uranyl ion. The success

of the coordination is investigated using IR spectroscopy and x-ray diffraction, and the magnetic

behavior is measured using a vibrating sample magnetometer.

Preliminary studies with the polypyridine-hydrazone ligand provide the foundation for verdazyl

polypyridine ligand synthesis and uranyl coordination. Success with studying the uranyl-radical

complex will allow for further studies with other actinides. This actinide coordination work is

supported by HIPPO, with the goal of further developing actinide specific ligands to continue

investigating the chemical and physical properties of these radical complexes.

David Brook

San Jose State University