Characterizing Pressure-Induced Uraniu mC ¢ HA gostic Bonds**

The diuranium(III) compound (UN''2)2(m-h 6 :h 6 - C6H6 )( N'' = N(SiMe3)2 )h as been studied using variable, high-pressure single-crystal X-ray crystallography ,a nd density functional theory .I nt his compound, the low-coordinate metal cations are coupled through p -a nd d-symmetric arene overlap and show close metal¢ CH contacts with the flexible methyl CH groups of the sterically encumbered amido ligands .T he metal- metal separation decreases with increasing pressure ,b ut the most significant structural changes are to the close contacts between ligand CH bonds and the Uc enters .A lthough the interatomic distances are suggestive of agostic-type interactions between the Ua nd ligand peripheral CH groups ,Q TAIM (quantum theory of atoms-in-molecules) computational anal- ysis suggests that there is no such interaction at ambient pressure .H owever ,Q TAIM and NBO analyses indicate that the interaction becomes agostic at 3.2 GPa.