Synthesis and Structure of Uranium‐Silylene Complexes

While carbene complexes of uranium have been known for over a decade, there are no reported examples of complexes between an actinide and a „heavy carbene.“ Herein, we report the syntheses and structures of the first uranium‐heavy tetrylene complexes: (CpSiMe3)3U‐Si[PhC(NR)2]R’ (R=tBu, R’=NMe2 1; R=iPr, R’=PhC(NiPr)2 2). Complex 1 features a kinetically robust uranium‐silicon bonding interaction, while the uranium‐silicon bond in 2 is easily disrupted thermally or by competing ligands in solution. Calculations reveal polarized σ bonds, but depending on the substituents at silicon a substantial π‐bonding interaction is also present. The complexes possess relatively high bond orders which suggests primarily covalent bonding between uranium and silicon. These results comprise a new frontier in actinide‐heavy main‐group bonding. We have a Si+Uation! Uranium–silylene complexes are reported, representing the first actinide‐heavy tetrylene bonding interactions. Preliminary reactivity studies suggest dative U−Si bonds that can be displaced thermally or with competing ligands. Electronic structure calculations reveal substantial covalent bonding character and even modest π‐bonding (see scheme).