Planar tetranuclear uranium hydride cluster supported by ansa-bis(cyclopentadienyl) ligands

Polynuclear metal hydride clusters play important roles in various catalytic processes, with most of the reported polynuclear metal hydride clusters adopting a polyhedral three-dimensional structure. Herein, we report the first example of a planar tetranuclear uranium hydride cluster [(CpCMe${}_2$CMe${}_2$Cp)U]${}_4$(µ${}_2$-H)${}_4$(µ${}_3$-H)${}_4$ (U${}_4$H${}_8$). It was synthesized by reacting an ansa-bis(cyclopentadienyl) ligand-supported uranium chloride precursor [(CpCMe${}_2$CMe${}_2$Cp)U]${}_3$(µ${}_2$-Cl)${}_3$(µ${}_3$-Cl)${}_2$ with NaHBEt${}_3$. The presence of hydrides in U${}_4$H${}_8$ was confirmed by NMR spectroscopy and its reactivity with phenol and carbon tetrachloride. DFT calculations also facilitated the determination of the hydrides' positions in U${}_4$H${}_8$, featuring four bridging µ${}_2$-H ligands and four face-capping µ${}_3$-H ligands, with the four U centers arranged in a rhombic geometry. The U${}_4$H${}_8$ represents not only the first example of planar polynuclear actinide metal hydride cluster but also the uranium hydride cluster with the highest nuclearity reported to date. (© 2024 Wiley-VCH GmbH)