Actinide‐Pnictide Chemistry: A Uranium Primary Alkyl Stibinide and a Diuranium Hexaantimonide‐Tetralithium Zintl Cluster

Abstract Structurally characterised U−Sb bonds are rare. Here, the synthesis and characterisation of [U(Tren DMBS ){Sb(H)C(H)(SiMe 3 ) 2 }] ( 5 , Tren DMBS =N(CH 2 CH 2 NSiMe 2 Bu t ) 3 ) and [{U(Tren TIPS )} 2 {Sb 3 (μ 6 ‐Li)(μ‐Li[THF] 2 ) 3 Sb 3 }] ( 6 , Tren TIPS =N(CH 2 CH 2 NSiPr i 3 ) 3 ) are reported. Complex 5 is an unprecedented primary stibinide actinide complex and 6 can be formulated as containing a unique triple decker 20 skeletal‐electron distorted closo tricapped Zintl cluster (Sb 3 Li 4 Sb 3 ) 2− that is analogous to the D 3h closo tricapped trigonal prism form of [Ge 9 ] 2− . Quantum chemical calculations emphasise polar U−Sb bonding in 5 and 6 , and that viewing (Sb 3 Li 4 Sb 3 ) 2− as a single unit rather than two distinct but contiguous (Sb 3 ) 3− units, themselves unprecedented in molecular actinide chemistry, is valid due to the presence of three weak (Sb 3 )⋯(Sb 3 ) (3, −1)‐bond critical points. Complexes 5 and 6 highlight the challenges of preparing polar U−Sb bonds and the underlying tendency for unpredictable cluster formation with Sb.