Unusual Actinyl Complexes with a Redox-Active N,S-Donor Ligand
Jing Su, Yu Gong, Enrique R. Batista, Ana F. Lucena, Leonor Maria, Joaquim Marçalo, Michael J. Van Stipdonk, Giel Berden, Jonathan Martens, Jos Oomens, John K. Gibson, Ping Yang
Abstract
Understanding the fundamental chemistry of soft N,S-donor ligands with actinides across the series is critical for separation science toward sustainable nuclear energy. This task is particularly challenging when the ligands are redox active. We herein report a series of actinyl complexes with a N,S-donor redox-active ligand that stabilizes different oxidation states across the actinide series. These complexes are isolated and characterized in the gas phase, along with high-level electronic structure studies. The redox-active N,S-donor ligand in the products, C 5 H 4 NS, acts as a monoanion in [U VI O 2 (C 5 H 4 NS – )] + but as a neutral radical with unpaired electrons localized on the sulfur atom in [Np V O 2 (C 5 H 4 NS • )] + and [Pu V O 2 (C 5 H 4 NS • )] +, resulting in different oxidation states for uranium and transuranic elements. This is rationalized by considering the relative energy levels of actinyl(VI) 5f orbitals and S 3p lone pair orbitals of the C 5 H 4 NS – ligand and the cooperativity between An–N and An–S bonds that provides additional stability for the transuranic elements.