Nucleophilic Reactivity of a Nitride-Bridged Diuranium(IV) Complex: CO2 and CS2 Functionalization

Thermolysis of the nitride-bridged diuranium(IV) complex Cs{(-N)U(OSi((OBu)-Bu-t)(3))(3)} (1) showed that the bridging nitride behaves as a strong nucleophile, promoting N-C bond formation by siloxide ligand fragmentation to yield an imido-bridged siloxide/silanediolate diuranium(IV) complex, Cs{(-(NBu)-Bu-t)(-O2Si((OBu)-Bu-t)(2))U-2(OSi((OBu)-Bu-t)(3))(5)}. Complex 1 displayed reactivity towards CS2 and CO2 at room temperature that is unprecedented in f-element chemistry, affording diverse N-functionalized products depending on the reaction stoichiometry. The reaction of 1 with two equivalents of CS2 yielded the thiocyanate/thiocarbonate complex Cs{(-NCS)(-CS3)U(OSi((OBu)-Bu-t)(3))(3)} via a putative NCS-/S2- intermediate. The reaction of 1 with one equivalent of CO2 resulted in deoxygenation and N-C bond formation, yielding the cyanate/oxo complex Cs{(-NCO)(-O)U(OSi((OBu)-Bu-t)(3))(3)}. Addition of excess CO2 to 1 led to the unprecedented dicarbamate product Cs{(-NC2O4)U(OSi((OBu)-Bu-t)(3))(3)}.